From 0e9eaea71c6c82cb21200651a85109d2c33faf8a Mon Sep 17 00:00:00 2001
From: Ben Henning <henning.benmax@gmail.com>
Date: Fri, 20 Sep 2019 01:33:56 -0700
Subject: [PATCH 01/14] Introduce a generic data-binding-enabled RecyclerView
 adapter. No tests have yet been added.

---
 app/build.gradle                              |   5 +-
 .../oppia/app/recyclerview/BindableAdapter.kt | 208 ++++++++++++++++++
 .../RecyclerViewBindingAdapter.kt             |  20 ++
 3 files changed, 231 insertions(+), 2 deletions(-)
 create mode 100644 app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt
 create mode 100644 app/src/main/java/org/oppia/app/recyclerview/RecyclerViewBindingAdapter.kt

diff --git a/app/build.gradle b/app/build.gradle
index 64ea16800a2..5a1823e94e8 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -61,10 +61,11 @@ dependencies {
       'androidx.constraintlayout:constraintlayout:1.1.3',
       'androidx.core:core-ktx:1.0.2',
       'androidx.lifecycle:lifecycle-runtime-ktx:2.2.0-alpha03',
+      'androidx.recyclerview:recyclerview:1.0.0',
       'com.google.dagger:dagger:2.24',
       "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version",
-      "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.2.1",
-      "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.2.1"
+      'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.2.1',
+      'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.2.1',
   )
   testImplementation(
       'androidx.test:core:1.2.0',
diff --git a/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt b/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt
new file mode 100644
index 00000000000..d665e9eb05a
--- /dev/null
+++ b/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt
@@ -0,0 +1,208 @@
+package org.oppia.app.recyclerview
+
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.databinding.ViewDataBinding
+import androidx.recyclerview.widget.RecyclerView
+import kotlin.reflect.KClass
+
+/** A function that returns the type of view that should can bind the specified data object. */
+typealias ComputeViewType<T> = (T) -> Int
+
+/**
+ * The default type of all views used for adapters that do not need to specify different view types.
+ */
+const val DEFAULT_VIEW_TYPE = 0
+
+private typealias ViewHolderFactory<T> = (ViewGroup) -> BindableAdapter.BindableViewHolder<T>
+
+/**
+ * A generic [RecyclerView.Adapter] that can be initialized using Android data-binding, and bind its
+ * own child views using Android data-binding (or custom View bind methods).
+ *
+ * This is loosely based on https://android.jlelse.eu/1bd08b4796b4 except the concept was extended
+ * to include seamlessly binding to views using data-binding in a type-safe and lifecycle-safe way.
+ */
+class BindableAdapter<T : Any> internal constructor(
+  private val computeViewType: ComputeViewType<T>,
+  private val viewHolderFactoryMap: Map<Int, ViewHolderFactory<T>>,
+  val dataClassType: KClass<T>
+) : RecyclerView.Adapter<BindableAdapter.BindableViewHolder<T>>() {
+  private val dataList: MutableList<T> = ArrayList()
+
+  // TODO(#170): Introduce support for stable IDs.
+
+  /** Sets the data of this adapter. This is expected to be called by Android via data-binding. */
+  fun setData(newDataList: List<T>) {
+    dataList.clear()
+    dataList += newDataList
+    // TODO(#171): Introduce diffing to notify subsets of the view to properly support animations
+    //  rather than re-binding the entire list upon any change.
+    notifyDataSetChanged()
+  }
+
+  /**
+   * Sets the data of this adapter in the same way as [setData], except with a different type.
+   *
+   * This method ensures the type of data being passed in is compatible with the type of this
+   * adapter. This helps ensure type compatibility at runtime in cases where the generic type of the
+   * adapter object is lost.
+   */
+  fun <T2: Any> setDataUnchecked(newDataList: List<T2>) {
+    // NB: This check only works if the list has any data in it. Since we can't use a reified type
+    // here (due to Android data binding not supporting custom adapters with inline functions), this
+    // method will succeed if types are different for empty lists (that is, List<T1> == List<T2>
+    // when T1 is not assignable to T2). This likely won't have bad side effects since any time a
+    // non-empty list is attempted to be bound, this crash will be correctly triggered.
+    newDataList.firstOrNull()?.let {
+      check(it.javaClass.isAssignableFrom(dataClassType.java)) {
+        "Trying to bind incompatible data to adapter. Data class type: ${it.javaClass}, " +
+            "expected adapter class type: $dataClassType."
+      }
+    }
+    @Suppress("UNCHECKED_CAST") // This is safe. See the above check.
+    setData(newDataList as List<T>)
+  }
+
+  override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BindableViewHolder<T> {
+    val viewHolderFactory = viewHolderFactoryMap[viewType]
+    checkNotNull(viewHolderFactory) { "Encountered missing view factory for type: $viewType" }
+    return viewHolderFactory(parent)
+  }
+
+  override fun getItemCount(): Int {
+    return dataList.size
+  }
+
+  override fun getItemViewType(position: Int): Int {
+    return computeViewType(dataList[position])
+  }
+
+  override fun onBindViewHolder(holder: BindableViewHolder<T>, position: Int) {
+    holder.bind(dataList[position])
+  }
+
+  /** A generic [RecyclerView.ViewHolder] that generically binds data to the specified view. */
+  abstract class BindableViewHolder<T> internal constructor(
+    view: View
+  ) : RecyclerView.ViewHolder(view) {
+    internal abstract fun bind(data: T)
+  }
+
+  /**
+   * Constructs a new [BindableAdapter]. Each type returned by the computer should have an
+   * associated view binder. If no computer is set, then [DEFAULT_VIEW_TYPE] is the default view
+   * type.
+   *
+   * Instances of [Builder] should be instantiated using [newBuilder].
+   */
+  class Builder<T : Any>(private val dataClassType: KClass<T>) {
+    private var computeViewType: ComputeViewType<T> = { DEFAULT_VIEW_TYPE }
+    private var viewHolderFactoryMap: MutableMap<Int, ViewHolderFactory<T>> = HashMap()
+
+    /**
+     * Registers a function which returns the type of view a specific data item corresponds to. This defaults to always
+     * assuming all views are the same time: [DEFAULT_VIEW_TYPE].
+     *
+     * This function must be used if multiple views need to be supported by the [RecyclerView].
+     *
+     * @return this
+     */
+    fun registerViewTypeComputer(computeViewType: ComputeViewType<T>): Builder<T> {
+      this.computeViewType = computeViewType
+      return this
+    }
+
+    /**
+     * Registers a [View] inflater and bind function for views of the specified view type (with default value
+     * [DEFAULT_VIEW_TYPE] for single-view [RecyclerView]s). Note that the viewType specified here must correspond to a
+     * view type registered in [registerViewTypeComputer] if non-default, or if any view type computer has been
+     * registered.
+     *
+     * The inflateView and bindView functions passed in here must not hold any references to UI objects except those
+     * that own the RecyclerView.
+     *
+     * @param inflateView function that takes a parent [ViewGroup] and returns a newly inflated [View] of type [V]
+     * @param bindView function that takes a [RecyclerView]-owned [View] of type [V] and binds a data element typed [T]
+     *     to it
+     * @return this
+     */
+    fun <V : View> registerViewBinder(
+      viewType: Int = DEFAULT_VIEW_TYPE, inflateView: (ViewGroup) -> V, bindView: (V, T) -> Unit
+    ): Builder<T> {
+      checkViewTypeIsUnique(viewType)
+      val viewHolderFactory: ViewHolderFactory<T> = { viewGroup ->
+        // This is lifecycle-safe since it will become dereferenced when the factory method returns.
+        // The version referenced in the anonymous BindableViewHolder object should be copied into a
+        // class field that binds that reference's lifetime to the view holder's lifetime. This
+        // approach avoids needing to perform an unsafe cast later when binding the view.
+        val inflatedView = inflateView(viewGroup)
+        object : BindableViewHolder<T>(inflatedView) {
+          override fun bind(data: T) {
+            bindView(inflatedView, data)
+          }
+        }
+      }
+      viewHolderFactoryMap[viewType] = viewHolderFactory
+      return this
+    }
+
+    /**
+     * Behaves in the same way as [registerViewBinder] except the inflate and bind methods correspond to a [View]
+     * data-binding typed [DB].
+     *
+     * @param inflateDataBinding a function that inflates the root view of a data-bound layout (e.g.
+     *     MyDataBinding::inflate). This may also be a function that initializes the data-binding with additional
+     *     properties as necessary.
+     * @param setViewModel a function that initializes the view model in the data-bound view (e.g.
+     *     MyDataBinding::setSpecialViewModel). This may also be a function that initializes the view model & other
+     *     view-accessible properties as necessary.
+     * @return this
+     */
+    fun <DB : ViewDataBinding> registerViewDataBinder(
+      viewType: Int = DEFAULT_VIEW_TYPE,
+      inflateDataBinding: (LayoutInflater, ViewGroup, Boolean) -> DB,
+      setViewModel: (DB, T) -> Unit
+    ): Builder<T> {
+      checkViewTypeIsUnique(viewType)
+      val viewHolderFactory: ViewHolderFactory<T> = { viewGroup ->
+        // See registerViewBinder() comments for why this approach should be lifecycle safe and not
+        // introduce memory leaks.
+        val binding = inflateDataBinding(
+          LayoutInflater.from(viewGroup.context),
+          viewGroup,
+          /* attachToRoot= */ false
+        )
+        object : BindableViewHolder<T>(binding.root) {
+          override fun bind(data: T) {
+            setViewModel(binding, data)
+          }
+        }
+      }
+      viewHolderFactoryMap[viewType] = viewHolderFactory
+      return this
+    }
+
+    private fun checkViewTypeIsUnique(viewType: Int) {
+      check(!viewHolderFactoryMap.containsKey(viewType)) {
+        "Cannot register a second view binder for view type: $viewType (current binder: " +
+            "${viewHolderFactoryMap[viewType]}."
+      }
+    }
+
+    /** Returns a new [BindableAdapter]. */
+    fun build(): BindableAdapter<T> {
+      val computeViewType = this.computeViewType
+      check(viewHolderFactoryMap.isNotEmpty()) { "At least one view holder must be registered" }
+      return BindableAdapter(computeViewType, viewHolderFactoryMap, dataClassType)
+    }
+
+    companion object {
+      /** Returns a new [Builder]. */
+      inline fun <reified T : Any> newBuilder(): Builder<T> {
+        return Builder(T::class)
+      }
+    }
+  }
+}
diff --git a/app/src/main/java/org/oppia/app/recyclerview/RecyclerViewBindingAdapter.kt b/app/src/main/java/org/oppia/app/recyclerview/RecyclerViewBindingAdapter.kt
new file mode 100644
index 00000000000..51b7e935975
--- /dev/null
+++ b/app/src/main/java/org/oppia/app/recyclerview/RecyclerViewBindingAdapter.kt
@@ -0,0 +1,20 @@
+package org.oppia.app.recyclerview
+
+import androidx.databinding.BindingAdapter
+import androidx.lifecycle.LiveData
+import androidx.recyclerview.widget.RecyclerView
+
+/**
+ * Binds the specified generic data to the adapter of the [RecyclerView]. This is called by
+ * Android's data binding framework and should not be used directly. For reference:
+ * https://android.jlelse.eu/1bd08b4796b4.
+ */
+@BindingAdapter("data")
+fun <T: Any> bindToRecyclerViewAdapter(recyclerView: RecyclerView, liveData: LiveData<List<T>>) {
+  liveData.value?.let { data ->
+    val adapter = recyclerView.adapter
+    checkNotNull(adapter) { "Cannot bind data to a RecyclerView missing its adapter." }
+    check(adapter is BindableAdapter<*>) { "Can only bind data to a BindableAdapter." }
+    adapter.setDataUnchecked(data)
+  }
+}

From 5c34d168aed0c2c62484150ef3a8064caa2c5f8a Mon Sep 17 00:00:00 2001
From: Ben Henning <henning.benmax@gmail.com>
Date: Sat, 21 Sep 2019 16:28:05 -0700
Subject: [PATCH 02/14] First attempt at introducing tests for BindableAdapter.
 They aren't fully working yet.

---
 app/build.gradle                              |   3 +
 app/src/main/AndroidManifest.xml              |   1 +
 .../oppia/app/activity/ActivityComponent.kt   |   2 +
 .../oppia/app/fragment/FragmentComponent.kt   |   2 +
 .../oppia/app/fragment/InjectableFragment.kt  |   2 +-
 .../java/org/oppia/app/home/HomeFragment.kt   |   2 +-
 .../oppia/app/player/audio/AudioFragment.kt   |   4 +-
 .../player/exploration/ExplorationFragment.kt |   2 +-
 .../oppia/app/player/state/StateFragment.kt   |   2 +-
 .../oppia/app/recyclerview/BindableAdapter.kt |   6 +-
 .../RecyclerViewBindingAdapter.kt             |   2 +-
 .../testing/BindableAdapterTestActivity.kt    |  14 +++
 .../testing/BindableAdapterTestFragment.kt    |  27 ++++
 .../BindableAdapterTestFragmentPresenter.kt   |  44 +++++++
 .../testing/BindableAdapterTestViewModel.kt   |  13 ++
 app/src/main/res/layout/test_fragment.xml     |  16 +++
 .../layout/test_text_view_no_data_binding.xml |   6 +
 .../app/recyclerview/BindableAdapterTest.kt   | 117 ++++++++++++++++++
 18 files changed, 255 insertions(+), 10 deletions(-)
 create mode 100644 app/src/main/java/org/oppia/app/testing/BindableAdapterTestActivity.kt
 create mode 100644 app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragment.kt
 create mode 100644 app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragmentPresenter.kt
 create mode 100644 app/src/main/java/org/oppia/app/testing/BindableAdapterTestViewModel.kt
 create mode 100644 app/src/main/res/layout/test_fragment.xml
 create mode 100644 app/src/main/res/layout/test_text_view_no_data_binding.xml
 create mode 100644 app/src/sharedTest/java/org/oppia/app/recyclerview/BindableAdapterTest.kt

diff --git a/app/build.gradle b/app/build.gradle
index 5a1823e94e8..882abd33cc1 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -12,6 +12,7 @@ android {
     targetSdkVersion 28
     versionCode 1
     versionName "1.0"
+    multiDexEnabled true
     testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     // https://developer.android.com/training/testing/junit-runner#ato-gradle
     testInstrumentationRunnerArguments clearPackageData: 'true'
@@ -61,8 +62,10 @@ dependencies {
       'androidx.constraintlayout:constraintlayout:1.1.3',
       'androidx.core:core-ktx:1.0.2',
       'androidx.lifecycle:lifecycle-runtime-ktx:2.2.0-alpha03',
+      'androidx.multidex:multidex:2.0.1',
       'androidx.recyclerview:recyclerview:1.0.0',
       'com.google.dagger:dagger:2.24',
+      'com.google.guava:guava:28.1-android',
       "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version",
       'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.2.1',
       'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.2.1',
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index c632728593b..248ecd6113b 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -22,5 +22,6 @@
         <category android:name="android.intent.category.DEFAULT"/>
       </intent-filter>
     </activity>
+    <activity android:name=".testing.BindableAdapterTestActivity"/>
   </application>
 </manifest>
diff --git a/app/src/main/java/org/oppia/app/activity/ActivityComponent.kt b/app/src/main/java/org/oppia/app/activity/ActivityComponent.kt
index 7102ac5af84..a73c9912c1d 100644
--- a/app/src/main/java/org/oppia/app/activity/ActivityComponent.kt
+++ b/app/src/main/java/org/oppia/app/activity/ActivityComponent.kt
@@ -6,6 +6,7 @@ import dagger.Subcomponent
 import org.oppia.app.fragment.FragmentComponent
 import org.oppia.app.home.HomeActivity
 import org.oppia.app.player.exploration.ExplorationActivity
+import org.oppia.app.testing.BindableAdapterTestActivity
 import javax.inject.Provider
 
 /** Root subcomponent for all activities. */
@@ -22,4 +23,5 @@ interface ActivityComponent {
 
   fun inject(explorationActivity: ExplorationActivity)
   fun inject(homeActivity: HomeActivity)
+  fun inject(bindableAdapterTestActivity: BindableAdapterTestActivity)
 }
diff --git a/app/src/main/java/org/oppia/app/fragment/FragmentComponent.kt b/app/src/main/java/org/oppia/app/fragment/FragmentComponent.kt
index 5392b95f3cc..7062123283c 100644
--- a/app/src/main/java/org/oppia/app/fragment/FragmentComponent.kt
+++ b/app/src/main/java/org/oppia/app/fragment/FragmentComponent.kt
@@ -7,6 +7,7 @@ import org.oppia.app.home.HomeFragment
 import org.oppia.app.player.exploration.ExplorationFragment
 import org.oppia.app.player.state.StateFragment
 import org.oppia.app.player.audio.AudioFragment
+import org.oppia.app.testing.BindableAdapterTestFragment
 
 /** Root subcomponent for all fragments. */
 @Subcomponent
@@ -22,4 +23,5 @@ interface FragmentComponent {
   fun inject(explorationFragment: ExplorationFragment)
   fun inject(homeFragment: HomeFragment)
   fun inject(stateFragment: StateFragment)
+  fun inject(bindableAdapterTestFragment: BindableAdapterTestFragment)
 }
diff --git a/app/src/main/java/org/oppia/app/fragment/InjectableFragment.kt b/app/src/main/java/org/oppia/app/fragment/InjectableFragment.kt
index 25c3628f07a..8042a88d3cc 100644
--- a/app/src/main/java/org/oppia/app/fragment/InjectableFragment.kt
+++ b/app/src/main/java/org/oppia/app/fragment/InjectableFragment.kt
@@ -16,7 +16,7 @@ abstract class InjectableFragment: Fragment() {
    */
   lateinit var fragmentComponent: FragmentComponent
 
-  override fun onAttach(context: Context?) {
+  override fun onAttach(context: Context) {
     super.onAttach(context)
     fragmentComponent = (requireActivity() as InjectableAppCompatActivity).createFragmentComponent(this)
   }
diff --git a/app/src/main/java/org/oppia/app/home/HomeFragment.kt b/app/src/main/java/org/oppia/app/home/HomeFragment.kt
index e3bc454853f..66a537947a4 100644
--- a/app/src/main/java/org/oppia/app/home/HomeFragment.kt
+++ b/app/src/main/java/org/oppia/app/home/HomeFragment.kt
@@ -12,7 +12,7 @@ import javax.inject.Inject
 class HomeFragment : InjectableFragment() {
   @Inject lateinit var homeFragmentController: HomeFragmentController
 
-  override fun onAttach(context: Context?) {
+  override fun onAttach(context: Context) {
     super.onAttach(context)
     fragmentComponent.inject(this)
   }
diff --git a/app/src/main/java/org/oppia/app/player/audio/AudioFragment.kt b/app/src/main/java/org/oppia/app/player/audio/AudioFragment.kt
index 19fbb2b25d3..3b5155d7927 100755
--- a/app/src/main/java/org/oppia/app/player/audio/AudioFragment.kt
+++ b/app/src/main/java/org/oppia/app/player/audio/AudioFragment.kt
@@ -17,7 +17,7 @@ class AudioFragment : InjectableFragment() {
 
   lateinit var languageInterface: LanguageInterface
 
-  override fun onAttach(context: Context?) {
+  override fun onAttach(context: Context) {
     super.onAttach(context)
     fragmentComponent.inject(this)
   }
@@ -42,7 +42,7 @@ class AudioFragment : InjectableFragment() {
       getDummyAudioLanguageList(),
       "en"
     )
-    dialogFragment.showNow(fragmentManager, TAG_DIALOG)
+    dialogFragment.showNow(fragmentManager!!, TAG_DIALOG)
   }
 
   private fun getDummyAudioLanguageList(): List<String> {
diff --git a/app/src/main/java/org/oppia/app/player/exploration/ExplorationFragment.kt b/app/src/main/java/org/oppia/app/player/exploration/ExplorationFragment.kt
index 337112eee6c..a60850d21cb 100755
--- a/app/src/main/java/org/oppia/app/player/exploration/ExplorationFragment.kt
+++ b/app/src/main/java/org/oppia/app/player/exploration/ExplorationFragment.kt
@@ -12,7 +12,7 @@ import javax.inject.Inject
 class ExplorationFragment : InjectableFragment() {
   @Inject lateinit var explorationFragmentPresenter: ExplorationFragmentPresenter
 
-  override fun onAttach(context: Context?) {
+  override fun onAttach(context: Context) {
     super.onAttach(context)
     fragmentComponent.inject(this)
   }
diff --git a/app/src/main/java/org/oppia/app/player/state/StateFragment.kt b/app/src/main/java/org/oppia/app/player/state/StateFragment.kt
index 20908b50513..b5b118f0238 100755
--- a/app/src/main/java/org/oppia/app/player/state/StateFragment.kt
+++ b/app/src/main/java/org/oppia/app/player/state/StateFragment.kt
@@ -12,7 +12,7 @@ import javax.inject.Inject
 class StateFragment : InjectableFragment() {
   @Inject lateinit var stateFragmentPresenter: StateFragmentPresenter
 
-  override fun onAttach(context: Context?) {
+  override fun onAttach(context: Context) {
     super.onAttach(context)
     fragmentComponent.inject(this)
   }
diff --git a/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt b/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt
index d665e9eb05a..d6ef7563e4a 100644
--- a/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt
+++ b/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt
@@ -27,7 +27,7 @@ private typealias ViewHolderFactory<T> = (ViewGroup) -> BindableAdapter.Bindable
 class BindableAdapter<T : Any> internal constructor(
   private val computeViewType: ComputeViewType<T>,
   private val viewHolderFactoryMap: Map<Int, ViewHolderFactory<T>>,
-  val dataClassType: KClass<T>
+  private val dataClassType: KClass<T>
 ) : RecyclerView.Adapter<BindableAdapter.BindableViewHolder<T>>() {
   private val dataList: MutableList<T> = ArrayList()
 
@@ -49,7 +49,7 @@ class BindableAdapter<T : Any> internal constructor(
    * adapter. This helps ensure type compatibility at runtime in cases where the generic type of the
    * adapter object is lost.
    */
-  fun <T2: Any> setDataUnchecked(newDataList: List<T2>) {
+  fun <T2 : Any> setDataUnchecked(newDataList: List<T2>) {
     // NB: This check only works if the list has any data in it. Since we can't use a reified type
     // here (due to Android data binding not supporting custom adapters with inline functions), this
     // method will succeed if types are different for empty lists (that is, List<T1> == List<T2>
@@ -194,7 +194,7 @@ class BindableAdapter<T : Any> internal constructor(
     /** Returns a new [BindableAdapter]. */
     fun build(): BindableAdapter<T> {
       val computeViewType = this.computeViewType
-      check(viewHolderFactoryMap.isNotEmpty()) { "At least one view holder must be registered" }
+      check(viewHolderFactoryMap.isNotEmpty()) { "At least one view binder must be registered" }
       return BindableAdapter(computeViewType, viewHolderFactoryMap, dataClassType)
     }
 
diff --git a/app/src/main/java/org/oppia/app/recyclerview/RecyclerViewBindingAdapter.kt b/app/src/main/java/org/oppia/app/recyclerview/RecyclerViewBindingAdapter.kt
index 51b7e935975..8eb836fd255 100644
--- a/app/src/main/java/org/oppia/app/recyclerview/RecyclerViewBindingAdapter.kt
+++ b/app/src/main/java/org/oppia/app/recyclerview/RecyclerViewBindingAdapter.kt
@@ -10,7 +10,7 @@ import androidx.recyclerview.widget.RecyclerView
  * https://android.jlelse.eu/1bd08b4796b4.
  */
 @BindingAdapter("data")
-fun <T: Any> bindToRecyclerViewAdapter(recyclerView: RecyclerView, liveData: LiveData<List<T>>) {
+fun <T : Any> bindToRecyclerViewAdapter(recyclerView: RecyclerView, liveData: LiveData<List<T>>) {
   liveData.value?.let { data ->
     val adapter = recyclerView.adapter
     checkNotNull(adapter) { "Cannot bind data to a RecyclerView missing its adapter." }
diff --git a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestActivity.kt b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestActivity.kt
new file mode 100644
index 00000000000..bec31a709e4
--- /dev/null
+++ b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestActivity.kt
@@ -0,0 +1,14 @@
+package org.oppia.app.testing
+
+import android.os.Bundle
+import org.oppia.app.activity.InjectableAppCompatActivity
+
+// TODO(#59): Make this activity only included in relevant tests instead of all prod builds.
+/** A test activity for the bindable RecyclerView adapter. */
+class BindableAdapterTestActivity: InjectableAppCompatActivity() {
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    activityComponent.inject(this)
+    supportFragmentManager.beginTransaction().add(BindableAdapterTestFragment(), BINDABLE_TEST_FRAGMENT_TAG).commitNow()
+  }
+}
diff --git a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragment.kt b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragment.kt
new file mode 100644
index 00000000000..0a9c477dc1a
--- /dev/null
+++ b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragment.kt
@@ -0,0 +1,27 @@
+package org.oppia.app.testing
+
+import android.content.Context
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import org.oppia.app.fragment.InjectableFragment
+import javax.inject.Inject
+
+const val BINDABLE_TEST_FRAGMENT_TAG = "bindable_adapter_test_fragment"
+
+// TODO(#59): Make this fragment only included in relevant tests instead of all prod builds.
+/** A test fragment for the bindable RecyclerView adapter. */
+class BindableAdapterTestFragment: InjectableFragment() {
+  @Inject
+  lateinit var bindableAdapterTestFragmentPresenter: BindableAdapterTestFragmentPresenter
+
+  override fun onAttach(context: Context) {
+    super.onAttach(context)
+    fragmentComponent.inject(this)
+  }
+
+  override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+    return bindableAdapterTestFragmentPresenter.handleCreateView(inflater, container)
+  }
+}
diff --git a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragmentPresenter.kt b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragmentPresenter.kt
new file mode 100644
index 00000000000..c066abadcb5
--- /dev/null
+++ b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragmentPresenter.kt
@@ -0,0 +1,44 @@
+package org.oppia.app.testing
+
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.annotation.VisibleForTesting
+import androidx.fragment.app.Fragment
+import org.oppia.app.databinding.TestFragmentBinding
+import org.oppia.app.recyclerview.BindableAdapter
+import org.oppia.app.viewmodel.ViewModelProvider
+import javax.inject.Inject
+
+/** The test-only fragment presenter corresponding to [BindableAdapterTestFragment]. */
+class BindableAdapterTestFragmentPresenter @Inject constructor(
+  private val fragment: Fragment,
+  private val viewModelProvider: ViewModelProvider<BindableAdapterTestViewModel>
+) {
+  @VisibleForTesting val viewModel: BindableAdapterTestViewModel by lazy {
+    getBindableAdapterTestViewModel()
+  }
+
+  companion object {
+    // TODO(#59): Move away from this fragile static testing state by leveraging a test-only DI graph that can be
+    //  configured within tests to provide the bindable adapter to be used by this presenter.
+    var testBindableAdapter: BindableAdapter<String>? = null
+  }
+
+  fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?): View? {
+    val binding = TestFragmentBinding.inflate(inflater, container, /* attachToRoot= */ false)
+    checkNotNull(testBindableAdapter) { "Expected a bindable adapter to be provided in a test module" }
+    binding.testRecyclerView.apply {
+      adapter = testBindableAdapter
+    }
+    binding.let {
+      it.viewModel = viewModel
+      it.lifecycleOwner = fragment
+    }
+    return binding.root
+  }
+
+  private fun getBindableAdapterTestViewModel(): BindableAdapterTestViewModel {
+    return viewModelProvider.getForFragment(fragment, BindableAdapterTestViewModel::class.java)
+  }
+}
diff --git a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestViewModel.kt b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestViewModel.kt
new file mode 100644
index 00000000000..3f695c4b2c6
--- /dev/null
+++ b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestViewModel.kt
@@ -0,0 +1,13 @@
+package org.oppia.app.testing
+
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import org.oppia.app.fragment.FragmentScope
+import javax.inject.Inject
+
+// TODO(#59): Make this view model only included in relevant tests instead of all prod builds.
+/** A [ViewModel] for testing the bindable RecyclerView adapter. */
+@FragmentScope
+class BindableAdapterTestViewModel @Inject constructor(): ViewModel() {
+  val dataListLiveData = MutableLiveData<List<String>>()
+}
diff --git a/app/src/main/res/layout/test_fragment.xml b/app/src/main/res/layout/test_fragment.xml
new file mode 100644
index 00000000000..b2b1e67b68d
--- /dev/null
+++ b/app/src/main/res/layout/test_fragment.xml
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- TODO(#59): Make this layout only accessible to tests. -->
+<layout
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  xmlns:app="http://schemas.android.com/apk/res-auto">
+  <data>
+    <variable name="viewModel" type="org.oppia.app.testing.BindableAdapterTestViewModel"/>
+  </data>
+
+  <androidx.recyclerview.widget.RecyclerView
+    android:id="@+id/test_recycler_view"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
+    app:data="@{viewModel.dataListLiveData}"/>
+</layout>
diff --git a/app/src/main/res/layout/test_text_view_no_data_binding.xml b/app/src/main/res/layout/test_text_view_no_data_binding.xml
new file mode 100644
index 00000000000..c5de925f746
--- /dev/null
+++ b/app/src/main/res/layout/test_text_view_no_data_binding.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<TextView
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  android:id="@+id/text_view_no_data_binding"
+  android:layout_width="match_parent"
+  android:layout_height="match_parent"/>
diff --git a/app/src/sharedTest/java/org/oppia/app/recyclerview/BindableAdapterTest.kt b/app/src/sharedTest/java/org/oppia/app/recyclerview/BindableAdapterTest.kt
new file mode 100644
index 00000000000..948022aa381
--- /dev/null
+++ b/app/src/sharedTest/java/org/oppia/app/recyclerview/BindableAdapterTest.kt
@@ -0,0 +1,117 @@
+package org.oppia.app.recyclerview
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import android.widget.TextView
+import androidx.lifecycle.MutableLiveData
+import androidx.recyclerview.widget.RecyclerView
+import androidx.test.core.app.ActivityScenario
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.espresso.Espresso.onIdle
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.assertion.ViewAssertions.matches
+import androidx.test.espresso.matcher.ViewMatchers.withId
+import androidx.test.espresso.matcher.ViewMatchers.withText
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.common.truth.Truth.assertThat
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.oppia.app.R
+import org.oppia.app.testing.BINDABLE_TEST_FRAGMENT_TAG
+import org.oppia.app.testing.BindableAdapterTestActivity
+import org.oppia.app.testing.BindableAdapterTestFragment
+import org.oppia.app.testing.BindableAdapterTestFragmentPresenter
+import org.oppia.app.testing.BindableAdapterTestViewModel
+
+const val ITEM_0 = "Item 0"
+const val ITEM_1 = "Item 1"
+
+/** Tests for [BindableAdapter]. */
+@RunWith(AndroidJUnit4::class)
+class BindableAdapterTest {
+  @Before
+  fun setUp() {
+    // Ensure that the bindable fragment's test state is properly reset each time.
+    BindableAdapterTestFragmentPresenter.testBindableAdapter = null
+  }
+  @After
+  fun tearDown() {
+    // Ensure that the bindable fragment's test state is properly cleaned up.
+    BindableAdapterTestFragmentPresenter.testBindableAdapter = null
+  }
+
+  @Test
+  fun testBindableAdapter_withOneViewType_noData_bindsNoViews() {
+    // Set up the adapter to be used for this test.
+    BindableAdapterTestFragmentPresenter.testBindableAdapter =
+      createSingleViewTypeNoDataBindingBindableAdapter()
+
+    ActivityScenario.launch(BindableAdapterTestActivity::class.java).use { scenario ->
+      scenario.onActivity { activity ->
+        val recyclerView: RecyclerView = getTestFragment(activity).view!!.findViewById(R.id.test_recycler_view)
+
+        assertThat(recyclerView.childCount).isEqualTo(0)
+      }
+    }
+  }
+
+  @Test
+  fun testBindableAdapter_withOneViewType_setItem_automaticallyBindsView() {
+    // Set up the adapter to be used for this test.
+    BindableAdapterTestFragmentPresenter.testBindableAdapter =
+      createSingleViewTypeNoDataBindingBindableAdapter()
+
+    ActivityScenario.launch(BindableAdapterTestActivity::class.java).use { scenario ->
+      scenario.onActivity { activity ->
+        val liveData = getRecyclerViewListLiveData(activity)
+        liveData.value = listOf(ITEM_0)
+        onIdle()
+
+        val recyclerView: RecyclerView = getTestFragment(activity).view!!.findViewById(R.id.test_recycler_view)
+        assertThat(recyclerView.childCount).isEqualTo(1)
+//        onView(withId(R.id.text_view_no_data_binding)).check(matches(withText(ITEM_0)))
+      }
+    }
+  }
+
+  // testBindableAdapter_withOneViewType_setMultipleItems_automaticallyBinds
+  // testBindableAdapter_withTwoViewTypes_setItems_autoBindsCorrectItemsPerTypes
+  // testBindableAdapter_withTwoViewTypes_setItems_autoBindsCorrectItemsPerTypes
+
+  private fun createSingleViewTypeNoDataBindingBindableAdapter(): BindableAdapter<String> {
+    return BindableAdapter.Builder
+      .newBuilder<String>()
+      .registerViewBinder(
+        inflateView = this::inflateTextViewWithoutDataBinding,
+        bindView = this::bindTextViewWithoutDataBinding
+      )
+      .build()
+  }
+
+  private fun inflateTextViewWithoutDataBinding(viewGroup: ViewGroup): TextView {
+    val inflater = LayoutInflater.from(ApplicationProvider.getApplicationContext())
+    return inflater.inflate(R.layout.test_text_view_no_data_binding, viewGroup, /* attachToRoot= */ false) as TextView
+  }
+
+  private fun bindTextViewWithoutDataBinding(textView: TextView, data: String) {
+    textView.text = data
+  }
+
+  private fun getRecyclerViewListLiveData(activity: BindableAdapterTestActivity): MutableLiveData<List<String>> {
+    return getTestViewModel(activity).dataListLiveData
+  }
+
+  private fun getTestViewModel(activity: BindableAdapterTestActivity): BindableAdapterTestViewModel {
+    return getTestFragmentPresenter(activity).viewModel
+  }
+
+  private fun getTestFragmentPresenter(activity: BindableAdapterTestActivity): BindableAdapterTestFragmentPresenter {
+    return getTestFragment(activity).bindableAdapterTestFragmentPresenter
+  }
+
+  private fun getTestFragment(activity: BindableAdapterTestActivity): BindableAdapterTestFragment {
+    return activity.supportFragmentManager.findFragmentByTag(BINDABLE_TEST_FRAGMENT_TAG) as BindableAdapterTestFragment
+  }
+}

From 9a89dee9bb68594bf0cd961712c0ced68be2ce66 Mon Sep 17 00:00:00 2001
From: James Xu <jamesxu@umich.edu>
Date: Fri, 27 Sep 2019 17:39:58 -0700
Subject: [PATCH 03/14] Updated view model

---
 .../topic/conceptcard/ConceptCardFragment.kt  |  4 +-
 .../topic/conceptcard/ConceptCardPresenter.kt |  8 ++-
 .../topic/conceptcard/ConceptCardViewModel.kt | 58 ++++++++++++++++++-
 .../res/layout/concept_card_example_view.xml  | 20 +++++++
 .../main/res/layout/conceptcard_fragment.xml  |  6 +-
 5 files changed, 86 insertions(+), 10 deletions(-)
 create mode 100644 app/src/main/res/layout/concept_card_example_view.xml

diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt
index f48309853fd..2d1ca49ac08 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt
@@ -10,7 +10,7 @@ import org.oppia.app.fragment.InjectableDialogFragment
 import javax.inject.Inject
 
 /* Fragment that displays a fullscreen dialog for concept cards */
-class ConceptCardFragment : InjectableDialogFragment() {
+class ConceptCardFragment(private val skillId: String) : InjectableDialogFragment() {
   @Inject lateinit var conceptCardPresenter: ConceptCardPresenter
 
   override fun onAttach(context: Context?) {
@@ -25,7 +25,7 @@ class ConceptCardFragment : InjectableDialogFragment() {
 
   override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
     super.onCreateView(inflater, container, savedInstanceState)
-    return conceptCardPresenter.handleCreateView(inflater, container)
+    return conceptCardPresenter.handleCreateView(inflater, container, skillId)
   }
 
   override fun onStart() {
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
index a3487a857a0..7851b8eb7d4 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
@@ -9,6 +9,7 @@ import org.oppia.app.R
 import org.oppia.app.databinding.ConceptcardFragmentBinding
 import org.oppia.app.fragment.FragmentScope
 import org.oppia.app.viewmodel.ViewModelProvider
+import org.oppia.domain.topic.TEST_SKILL_ID_0
 import javax.inject.Inject
 
 /** Presenter for [ConceptCardFragment], sets up bindings from ViewModel */
@@ -17,17 +18,18 @@ class ConceptCardPresenter @Inject constructor(
   private val fragment: Fragment,
   private val viewModelProvider: ViewModelProvider<ConceptCardViewModel>
 ){
-  fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?): View? {
+  fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?, skillId: String): View? {
+    val viewModel = getConceptCardViewModel()
+    viewModel.setSkillId(skillId)
     val binding = ConceptcardFragmentBinding.inflate(inflater, container, /* attachToRoot= */ false)
     binding.conceptCardToolbar.setNavigationIcon(R.drawable.ic_close_white_24dp)
     binding.conceptCardToolbar.setNavigationOnClickListener {
       (fragment as? DialogFragment)?.dismiss()
     }
     binding.let {
-      it.viewModel = getConceptCardViewModel()
+      it.viewModel = viewModel
       it.lifecycleOwner = fragment
     }
-
     return binding.root
   }
 
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardViewModel.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardViewModel.kt
index 8362ea37b6e..d424d7c535e 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardViewModel.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardViewModel.kt
@@ -1,11 +1,63 @@
 package org.oppia.app.topic.conceptcard
 
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.Transformations
 import androidx.lifecycle.ViewModel
+import kotlinx.coroutines.processNextEventInCurrentThread
 import org.oppia.app.fragment.FragmentScope
+import org.oppia.app.model.ConceptCard
+import org.oppia.app.model.SubtitledHtml
+import org.oppia.domain.topic.TEST_SKILL_ID_0
+import org.oppia.domain.topic.TopicController
+import org.oppia.util.data.AsyncResult
+import org.oppia.util.logging.Logger
 import javax.inject.Inject
 
 /** [ViewModel] for concept card, providing rich text and worked examples */
 @FragmentScope
-class ConceptCardViewModel @Inject constructor() : ViewModel() {
-  fun getDummyText() = "hello world"
-}
\ No newline at end of file
+class ConceptCardViewModel @Inject constructor(
+  private val topicController: TopicController,
+  private val logger: Logger
+) : ViewModel() {
+
+  private lateinit var skillId: String
+
+  val conceptCardLiveData: LiveData<ConceptCard> by lazy {
+    processConceptCardLiveData()
+  }
+
+  val workedExamplesLiveData: LiveData<List<SubtitledHtml>> by lazy {
+    processWorkedExamplesLiveData()
+  }
+
+  /** Sets the value of skillId. Must be called before setting ViewModel to binding. */
+  fun setSkillId(id: String) {
+    skillId = id
+  }
+
+  private val conceptCardResultLiveData: LiveData<AsyncResult<ConceptCard>> by lazy {
+    topicController.getConceptCard(skillId)
+  }
+
+  private fun processConceptCardLiveData(): LiveData<ConceptCard> {
+    return Transformations.map(conceptCardResultLiveData, ::processConceptCardResult)
+  }
+
+  private fun processWorkedExamplesLiveData(): LiveData<List<SubtitledHtml>> {
+    return Transformations.map(conceptCardResultLiveData, ::processConceptCardWorkExamples)
+  }
+
+  private fun processConceptCardResult(conceptCardResult: AsyncResult<ConceptCard>): ConceptCard {
+    if (conceptCardResult.isFailure()) {
+      logger.e("ConceptCardFragment", "Failed to retrieve Concept Card: " + conceptCardResult.getErrorOrNull())
+    }
+    return conceptCardResult.getOrDefault(ConceptCard.getDefaultInstance())
+  }
+
+  private fun processConceptCardWorkExamples(conceptCardResult: AsyncResult<ConceptCard>): List<SubtitledHtml> {
+    if (conceptCardResult.isFailure()) {
+      logger.e("ConceptCardFragment", "Failed to retrieve Concept Card: " + conceptCardResult.getErrorOrNull())
+    }
+    return conceptCardResult.getOrDefault(ConceptCard.getDefaultInstance()).workedExampleList
+  }
+}
diff --git a/app/src/main/res/layout/concept_card_example_view.xml b/app/src/main/res/layout/concept_card_example_view.xml
new file mode 100644
index 00000000000..0a9c797e5fd
--- /dev/null
+++ b/app/src/main/res/layout/concept_card_example_view.xml
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layout
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  xmlns:app="http://schemas.android.com/apk/res-auto">
+  <data>
+    <variable
+      name="conceptCard"
+      type="org.oppia.app.model.ConceptCard" />
+  </data>
+  <androidx.constraintlayout.widget.ConstraintLayout
+    android:layout_width="wrap_content"
+    android:layout_height="match_parent">
+    <TextView
+      app:layout_constraintTop_toTopOf="parent"
+      app:layout_constraintStart_toStartOf="parent"
+      app:layout_constraintEnd_toEndOf="parent"
+      android:layout_width="wrap_content"
+      android:layout_height="wrap_content" />
+  </androidx.constraintlayout.widget.ConstraintLayout>
+</layout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/conceptcard_fragment.xml b/app/src/main/res/layout/conceptcard_fragment.xml
index aefaca6f1c2..f30db1cb96a 100644
--- a/app/src/main/res/layout/conceptcard_fragment.xml
+++ b/app/src/main/res/layout/conceptcard_fragment.xml
@@ -3,6 +3,7 @@
   xmlns:app="http://schemas.android.com/apk/res-auto">
 
   <data>
+    <import type="android.view.View"/>
     <variable
       name="viewModel"
       type="org.oppia.app.topic.conceptcard.ConceptCardViewModel"/>
@@ -29,11 +30,12 @@
       app:layout_constraintRight_toRightOf="parent"
       app:layout_constraintBottom_toBottomOf="parent">
       <TextView
-        android:id="@+id/rich_text_card"
+        android:id="@+id/explanation"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:textColor="@android:color/black"
-        android:text="@{viewModel.getDummyText()}" />
+        android:visibility="@{viewModel.conceptCardLiveData.hasExplanation() ? View.VISIBLE : View.GONE}"
+        android:text="@{viewModel.conceptCardLiveData.explanation.getHtml()}" />
     </ScrollView>
 
   </androidx.constraintlayout.widget.ConstraintLayout>

From 601f4b694e6dd4a4dd30ad869ca78f278c94ecc9 Mon Sep 17 00:00:00 2001
From: James Xu <jamesxu@umich.edu>
Date: Sat, 28 Sep 2019 12:25:01 -0700
Subject: [PATCH 04/14] Added bindable recycler view and test activity

---
 app/src/main/AndroidManifest.xml              |  1 +
 .../oppia/app/activity/ActivityComponent.kt   |  2 ++
 .../topic/conceptcard/ConceptCardPresenter.kt | 21 +++++++++++++++
 .../ConceptCardFragmentTestActivity.kt        | 16 +++++++++++
 ...nceptCardFragmentTestActivityController.kt | 20 ++++++++++++++
 .../res/layout/concept_card_example_view.xml  | 12 +++++----
 .../concept_card_fragment_test_activity.xml   | 15 +++++++++++
 .../main/res/layout/conceptcard_fragment.xml  | 27 ++++++++++++-------
 .../conceptcard/ConceptCardFragmentTest.kt    |  7 ++---
 9 files changed, 104 insertions(+), 17 deletions(-)
 create mode 100644 app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt
 create mode 100644 app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
 create mode 100644 app/src/main/res/layout/concept_card_fragment_test_activity.xml

diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 0958158687b..f99e5ddc885 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -12,6 +12,7 @@
     android:supportsRtl="true"
     android:theme="@style/OppiaTheme">
     <activity android:name=".player.exploration.ExplorationActivity"/>
+    <activity android:name="org.oppia.app.topic.conceptcard.testing.ConceptCardFragmentTestActivity"/>
     <activity android:name="org.oppia.app.home.HomeActivity">
       <intent-filter>
         <action android:name="android.intent.action.MAIN"/>
diff --git a/app/src/main/java/org/oppia/app/activity/ActivityComponent.kt b/app/src/main/java/org/oppia/app/activity/ActivityComponent.kt
index 7102ac5af84..882f9655678 100644
--- a/app/src/main/java/org/oppia/app/activity/ActivityComponent.kt
+++ b/app/src/main/java/org/oppia/app/activity/ActivityComponent.kt
@@ -6,6 +6,7 @@ import dagger.Subcomponent
 import org.oppia.app.fragment.FragmentComponent
 import org.oppia.app.home.HomeActivity
 import org.oppia.app.player.exploration.ExplorationActivity
+import org.oppia.app.topic.conceptcard.testing.ConceptCardFragmentTestActivity
 import javax.inject.Provider
 
 /** Root subcomponent for all activities. */
@@ -22,4 +23,5 @@ interface ActivityComponent {
 
   fun inject(explorationActivity: ExplorationActivity)
   fun inject(homeActivity: HomeActivity)
+  fun inject(conceptCardFragmentTestActivity: ConceptCardFragmentTestActivity)
 }
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
index 7851b8eb7d4..70749841511 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
@@ -1,13 +1,19 @@
 package org.oppia.app.topic.conceptcard
 
+import android.content.Context
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.DialogFragment
 import androidx.fragment.app.Fragment
+import androidx.recyclerview.widget.LinearLayoutManager
 import org.oppia.app.R
+import org.oppia.app.application.ApplicationContext
+import org.oppia.app.databinding.ConceptCardExampleViewBinding
 import org.oppia.app.databinding.ConceptcardFragmentBinding
 import org.oppia.app.fragment.FragmentScope
+import org.oppia.app.model.SubtitledHtml
+import org.oppia.app.recyclerview.BindableAdapter
 import org.oppia.app.viewmodel.ViewModelProvider
 import org.oppia.domain.topic.TEST_SKILL_ID_0
 import javax.inject.Inject
@@ -15,6 +21,7 @@ import javax.inject.Inject
 /** Presenter for [ConceptCardFragment], sets up bindings from ViewModel */
 @FragmentScope
 class ConceptCardPresenter @Inject constructor(
+  @ApplicationContext private val context: Context,
   private val fragment: Fragment,
   private val viewModelProvider: ViewModelProvider<ConceptCardViewModel>
 ){
@@ -26,6 +33,11 @@ class ConceptCardPresenter @Inject constructor(
     binding.conceptCardToolbar.setNavigationOnClickListener {
       (fragment as? DialogFragment)?.dismiss()
     }
+    binding.workedExamples.apply {
+      adapter = createRecyclerViewAdapter()
+      layoutManager = LinearLayoutManager(context)
+    }
+
     binding.let {
       it.viewModel = viewModel
       it.lifecycleOwner = fragment
@@ -36,4 +48,13 @@ class ConceptCardPresenter @Inject constructor(
   private fun getConceptCardViewModel(): ConceptCardViewModel {
     return viewModelProvider.getForFragment(fragment, ConceptCardViewModel::class.java)
   }
+
+  private fun createRecyclerViewAdapter(): BindableAdapter<SubtitledHtml> {
+    return BindableAdapter.Builder
+      .newBuilder<SubtitledHtml>()
+      .registerViewDataBinder(
+        inflateDataBinding = ConceptCardExampleViewBinding::inflate,
+        setViewModel = ConceptCardExampleViewBinding::setSubtitledHtml)
+      .build()
+  }
 }
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt
new file mode 100644
index 00000000000..1fadbcde619
--- /dev/null
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt
@@ -0,0 +1,16 @@
+package org.oppia.app.topic.conceptcard.testing
+
+import android.os.Bundle
+import org.oppia.app.activity.InjectableAppCompatActivity
+import javax.inject.Inject
+
+class ConceptCardFragmentTestActivity : InjectableAppCompatActivity() {
+
+  @Inject lateinit var conceptCardFragmentTestActivityController: ConceptCardFragmentTestActivityController
+
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    activityComponent.inject(this)
+    conceptCardFragmentTestActivityController.handleOnCreate()
+  }
+}
\ No newline at end of file
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
new file mode 100644
index 00000000000..e27dc61f65b
--- /dev/null
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
@@ -0,0 +1,20 @@
+package org.oppia.app.topic.conceptcard.testing
+
+import androidx.appcompat.app.AppCompatActivity
+import kotlinx.android.synthetic.main.concept_card_fragment_test_activity.*
+import org.oppia.app.R
+import org.oppia.app.topic.conceptcard.ConceptCardFragment
+import org.oppia.domain.topic.TEST_SKILL_ID_2
+import javax.inject.Inject
+
+private const val TAG_CONCEPT_CARD_DIALOG = "CONCEPT_CARD_DIALOG"
+
+class ConceptCardFragmentTestActivityController @Inject constructor(private val activity: AppCompatActivity) {
+  fun handleOnCreate() {
+    activity.setContentView(R.layout.concept_card_fragment_test_activity)
+    activity.open_dialog.setOnClickListener {
+      val frag = ConceptCardFragment(TEST_SKILL_ID_2)
+      frag.showNow(activity.supportFragmentManager, TAG_CONCEPT_CARD_DIALOG)
+    }
+  }
+}
\ No newline at end of file
diff --git a/app/src/main/res/layout/concept_card_example_view.xml b/app/src/main/res/layout/concept_card_example_view.xml
index 0a9c797e5fd..0fae774ed55 100644
--- a/app/src/main/res/layout/concept_card_example_view.xml
+++ b/app/src/main/res/layout/concept_card_example_view.xml
@@ -4,17 +4,19 @@
   xmlns:app="http://schemas.android.com/apk/res-auto">
   <data>
     <variable
-      name="conceptCard"
-      type="org.oppia.app.model.ConceptCard" />
+      name="subtitledHtml"
+      type="org.oppia.app.model.SubtitledHtml" />
   </data>
   <androidx.constraintlayout.widget.ConstraintLayout
-    android:layout_width="wrap_content"
-    android:layout_height="match_parent">
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content">
     <TextView
       app:layout_constraintTop_toTopOf="parent"
       app:layout_constraintStart_toStartOf="parent"
       app:layout_constraintEnd_toEndOf="parent"
       android:layout_width="wrap_content"
-      android:layout_height="wrap_content" />
+      android:layout_height="wrap_content"
+      android:textColor="@android:color/black"
+      android:text="@{subtitledHtml.getHtml()}"/>
   </androidx.constraintlayout.widget.ConstraintLayout>
 </layout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/concept_card_fragment_test_activity.xml b/app/src/main/res/layout/concept_card_fragment_test_activity.xml
new file mode 100644
index 00000000000..63a60b277ce
--- /dev/null
+++ b/app/src/main/res/layout/concept_card_fragment_test_activity.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout android:layout_height="match_parent"
+  android:layout_width="match_parent"
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  xmlns:app="http://schemas.android.com/apk/res-auto">
+  <Button
+    android:id="@+id/open_dialog"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:text="Open Concept Card Dialog"
+    app:layout_constraintTop_toTopOf="parent"
+    app:layout_constraintBottom_toBottomOf="parent"
+    app:layout_constraintStart_toStartOf="parent"
+    app:layout_constraintEnd_toEndOf="parent"/>
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/conceptcard_fragment.xml b/app/src/main/res/layout/conceptcard_fragment.xml
index f30db1cb96a..f998c0baf86 100644
--- a/app/src/main/res/layout/conceptcard_fragment.xml
+++ b/app/src/main/res/layout/conceptcard_fragment.xml
@@ -1,18 +1,15 @@
 <layout
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto">
-
   <data>
     <import type="android.view.View"/>
     <variable
       name="viewModel"
       type="org.oppia.app.topic.conceptcard.ConceptCardViewModel"/>
   </data>
-
   <androidx.constraintlayout.widget.ConstraintLayout
     android:layout_height="match_parent"
     android:layout_width="match_parent"
-
     android:background="@color/colorConceptCardBackground">
     <androidx.appcompat.widget.Toolbar
       android:id="@+id/concept_card_toolbar"
@@ -29,14 +26,26 @@
       app:layout_constraintLeft_toLeftOf="parent"
       app:layout_constraintRight_toRightOf="parent"
       app:layout_constraintBottom_toBottomOf="parent">
-      <TextView
-        android:id="@+id/explanation"
+      <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:textColor="@android:color/black"
-        android:visibility="@{viewModel.conceptCardLiveData.hasExplanation() ? View.VISIBLE : View.GONE}"
-        android:text="@{viewModel.conceptCardLiveData.explanation.getHtml()}" />
+        android:orientation="vertical"
+        android:paddingTop="10dp">
+        <TextView
+          android:id="@+id/explanation"
+          android:layout_width="match_parent"
+          android:layout_height="wrap_content"
+          android:textColor="@android:color/black"
+          android:gravity="center"
+          android:visibility="@{viewModel.conceptCardLiveData.hasExplanation() ? View.VISIBLE : View.GONE}"
+          android:text="@{viewModel.conceptCardLiveData.explanation.getHtml()}" />
+        <androidx.recyclerview.widget.RecyclerView
+          android:id="@+id/worked_examples"
+          android:layout_width="match_parent"
+          android:layout_height="wrap_content"
+          app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
+          app:data="@{viewModel.workedExamplesLiveData}" />
+      </LinearLayout>
     </ScrollView>
-
   </androidx.constraintlayout.widget.ConstraintLayout>
 </layout>
\ No newline at end of file
diff --git a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
index 5d739a7756f..cef43fdcc0d 100644
--- a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
+++ b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
@@ -19,6 +19,7 @@ import org.junit.Test
 import org.junit.runner.RunWith
 import org.oppia.app.R
 import org.oppia.app.home.HomeActivity
+import org.oppia.app.topic.conceptcard.testing.ConceptCardFragmentTestActivity
 import org.oppia.util.threading.BackgroundDispatcher
 import org.oppia.util.threading.BlockingDispatcher
 import javax.inject.Singleton
@@ -29,9 +30,9 @@ class ConceptCardFragmentTest {
 
   @Test
   fun testConceptCardFragment_loadFragment_textIsDisplayed() {
-    // I'm not sure how to launch just the fragment because it doesn't have its own activity
-    ActivityScenario.launch(HomeActivity::class.java).use {
-      Espresso.onView(withId(R.id.rich_text_card)).check(matches(withText("Hello World")))
+    ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
+      Espresso.onView(withId(R.id.open_dialog)).perform(click())
+      Espresso.onView(withId(R.id.explanation)).check(matches(withText("Explanation without rich text.")))
     }
   }
 

From f2f4f527a5c92e8e1ed2a68c711e92bedb4d3838 Mon Sep 17 00:00:00 2001
From: James Xu <jamesxu@umich.edu>
Date: Mon, 30 Sep 2019 10:33:11 -0700
Subject: [PATCH 05/14] Finished test cases

---
 .../app/topic/conceptcard/ConceptCardPresenter.kt  |  6 ++----
 .../app/topic/conceptcard/ConceptCardViewModel.kt  |  4 ++--
 .../testing/ConceptCardFragmentTestActivity.kt     |  2 +-
 .../ConceptCardFragmentTestActivityController.kt   |  2 +-
 .../topic/conceptcard/ConceptCardFragmentTest.kt   | 14 +++++++++++---
 5 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
index 70749841511..a84d39732df 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
@@ -1,6 +1,5 @@
 package org.oppia.app.topic.conceptcard
 
-import android.content.Context
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -8,23 +7,22 @@ import androidx.fragment.app.DialogFragment
 import androidx.fragment.app.Fragment
 import androidx.recyclerview.widget.LinearLayoutManager
 import org.oppia.app.R
-import org.oppia.app.application.ApplicationContext
 import org.oppia.app.databinding.ConceptCardExampleViewBinding
 import org.oppia.app.databinding.ConceptcardFragmentBinding
 import org.oppia.app.fragment.FragmentScope
 import org.oppia.app.model.SubtitledHtml
 import org.oppia.app.recyclerview.BindableAdapter
 import org.oppia.app.viewmodel.ViewModelProvider
-import org.oppia.domain.topic.TEST_SKILL_ID_0
 import javax.inject.Inject
 
 /** Presenter for [ConceptCardFragment], sets up bindings from ViewModel */
 @FragmentScope
 class ConceptCardPresenter @Inject constructor(
-  @ApplicationContext private val context: Context,
   private val fragment: Fragment,
   private val viewModelProvider: ViewModelProvider<ConceptCardViewModel>
 ){
+
+  /** Sets up data binding and adapter for RecyclerView */
   fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?, skillId: String): View? {
     val viewModel = getConceptCardViewModel()
     viewModel.setSkillId(skillId)
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardViewModel.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardViewModel.kt
index d424d7c535e..73a3822f1d3 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardViewModel.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardViewModel.kt
@@ -3,11 +3,9 @@ package org.oppia.app.topic.conceptcard
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.Transformations
 import androidx.lifecycle.ViewModel
-import kotlinx.coroutines.processNextEventInCurrentThread
 import org.oppia.app.fragment.FragmentScope
 import org.oppia.app.model.ConceptCard
 import org.oppia.app.model.SubtitledHtml
-import org.oppia.domain.topic.TEST_SKILL_ID_0
 import org.oppia.domain.topic.TopicController
 import org.oppia.util.data.AsyncResult
 import org.oppia.util.logging.Logger
@@ -22,10 +20,12 @@ class ConceptCardViewModel @Inject constructor(
 
   private lateinit var skillId: String
 
+  /** Live Data for concept card explanation */
   val conceptCardLiveData: LiveData<ConceptCard> by lazy {
     processConceptCardLiveData()
   }
 
+  /** Live Data for concept card worked examples. */
   val workedExamplesLiveData: LiveData<List<SubtitledHtml>> by lazy {
     processWorkedExamplesLiveData()
   }
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt
index 1fadbcde619..e4dff578f1f 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt
@@ -13,4 +13,4 @@ class ConceptCardFragmentTestActivity : InjectableAppCompatActivity() {
     activityComponent.inject(this)
     conceptCardFragmentTestActivityController.handleOnCreate()
   }
-}
\ No newline at end of file
+}
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
index e27dc61f65b..42c86a8c14e 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
@@ -17,4 +17,4 @@ class ConceptCardFragmentTestActivityController @Inject constructor(private val
       frag.showNow(activity.supportFragmentManager, TAG_CONCEPT_CARD_DIALOG)
     }
   }
-}
\ No newline at end of file
+}
diff --git a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
index cef43fdcc0d..1cb8ff5809e 100644
--- a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
+++ b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
@@ -6,10 +6,10 @@ import androidx.test.core.app.ActivityScenario
 import androidx.test.espresso.Espresso
 import androidx.test.espresso.action.ViewActions.click
 import androidx.test.espresso.assertion.ViewAssertions.matches
-import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
 import androidx.test.espresso.matcher.ViewMatchers.withId
 import androidx.test.espresso.matcher.ViewMatchers.withText
 import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
 import dagger.BindsInstance
 import dagger.Component
 import dagger.Module
@@ -18,7 +18,6 @@ import kotlinx.coroutines.CoroutineDispatcher
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.oppia.app.R
-import org.oppia.app.home.HomeActivity
 import org.oppia.app.topic.conceptcard.testing.ConceptCardFragmentTestActivity
 import org.oppia.util.threading.BackgroundDispatcher
 import org.oppia.util.threading.BlockingDispatcher
@@ -29,13 +28,22 @@ import javax.inject.Singleton
 class ConceptCardFragmentTest {
 
   @Test
-  fun testConceptCardFragment_loadFragment_textIsDisplayed() {
+  fun testConceptCardFragment_openDialogFragment_explanationIsDisplayed() {
     ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
       Espresso.onView(withId(R.id.open_dialog)).perform(click())
       Espresso.onView(withId(R.id.explanation)).check(matches(withText("Explanation without rich text.")))
     }
   }
 
+  @Test
+  fun testConceptCardFragment_openDialogFragment_workedExamplesIsDisplayed() {
+    ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
+      Espresso.onView(withId(R.id.open_dialog)).perform(click())
+      Espresso.onView(withText("Worked example without rich text.")).check(matches(isDisplayed()))
+      Espresso.onView(withText("Second worked example.")).check(matches(isDisplayed()))
+    }
+  }
+
   @Module
   class TestModule {
     @Provides

From c7d871e4b9d2d5921cd929db5061cb8ca8eaf653 Mon Sep 17 00:00:00 2001
From: James Xu <jamesxu@umich.edu>
Date: Mon, 30 Sep 2019 13:44:05 -0700
Subject: [PATCH 06/14] Using bundle to get skillId

---
 .../topic/conceptcard/ConceptCardFragment.kt  | 23 ++++++++++++++++++-
 ...nceptCardFragmentTestActivityController.kt |  2 +-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt
index 2d1ca49ac08..efdef90a791 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt
@@ -7,10 +7,29 @@ import android.view.View
 import android.view.ViewGroup
 import org.oppia.app.R
 import org.oppia.app.fragment.InjectableDialogFragment
+import org.oppia.domain.topic.TEST_SKILL_ID_2
 import javax.inject.Inject
 
+private const val KEY_SKILL_ID = "SKILL_ID"
+
 /* Fragment that displays a fullscreen dialog for concept cards */
-class ConceptCardFragment(private val skillId: String) : InjectableDialogFragment() {
+class ConceptCardFragment : InjectableDialogFragment() {
+
+  companion object {
+    /**
+     * Creates a new instance of a DialogFragment to display content
+     * @param skillId Used in TopicController to get correct concept card data.
+     * @return [ConceptCardFragment]: DialogFragment
+     */
+    fun newInstance(skillId: String): ConceptCardFragment {
+      val conceptCardFrag = ConceptCardFragment()
+      val args = Bundle()
+      args.putString(KEY_SKILL_ID, skillId)
+      conceptCardFrag.arguments = args
+      return conceptCardFrag
+    }
+  }
+
   @Inject lateinit var conceptCardPresenter: ConceptCardPresenter
 
   override fun onAttach(context: Context?) {
@@ -25,6 +44,8 @@ class ConceptCardFragment(private val skillId: String) : InjectableDialogFragmen
 
   override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
     super.onCreateView(inflater, container, savedInstanceState)
+    val args = checkNotNull(arguments) { "Expected arguments to be pass to ConceptCardFragment" }
+    val skillId = args.getString(KEY_SKILL_ID, TEST_SKILL_ID_2)
     return conceptCardPresenter.handleCreateView(inflater, container, skillId)
   }
 
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
index 42c86a8c14e..4960ad636e1 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
@@ -13,7 +13,7 @@ class ConceptCardFragmentTestActivityController @Inject constructor(private val
   fun handleOnCreate() {
     activity.setContentView(R.layout.concept_card_fragment_test_activity)
     activity.open_dialog.setOnClickListener {
-      val frag = ConceptCardFragment(TEST_SKILL_ID_2)
+      val frag = ConceptCardFragment.newInstance(TEST_SKILL_ID_2)
       frag.showNow(activity.supportFragmentManager, TAG_CONCEPT_CARD_DIALOG)
     }
   }

From 352c5de3ddbae5553dc2c62ab564173a99167f7d Mon Sep 17 00:00:00 2001
From: James Xu <jamesxu@umich.edu>
Date: Tue, 1 Oct 2019 16:39:08 -0700
Subject: [PATCH 07/14] Minor fixes and added tests

---
 app/build.gradle                              |  1 +
 .../topic/conceptcard/ConceptCardFragment.kt  |  5 +--
 .../topic/conceptcard/ConceptCardPresenter.kt |  6 +--
 .../ConceptCardFragmentTestActivity.kt        |  3 +-
 ...nceptCardFragmentTestActivityPresenter.kt} | 10 ++++-
 .../res/layout/concept_card_example_view.xml  |  2 +-
 ...fragment.xml => concept_card_fragment.xml} |  2 +-
 .../concept_card_fragment_test_activity.xml   | 21 +++++-----
 .../conceptcard/ConceptCardFragmentTest.kt    | 38 +++++++++++++++++--
 9 files changed, 61 insertions(+), 27 deletions(-)
 rename app/src/main/java/org/oppia/app/topic/conceptcard/testing/{ConceptCardFragmentTestActivityController.kt => ConceptCardFragmentTestActivityPresenter.kt} (58%)
 rename app/src/main/res/layout/{conceptcard_fragment.xml => concept_card_fragment.xml} (99%)

diff --git a/app/build.gradle b/app/build.gradle
index 5a1823e94e8..17cfabcfe3a 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -78,6 +78,7 @@ dependencies {
       'androidx.test:core:1.2.0',
       'androidx.test.espresso:espresso-core:3.2.0',
       'androidx.test.ext:junit:1.1.1',
+      'androidx.test:rules:1.2.0',
       'androidx.test:runner:1.2.0',
       'com.google.truth:truth:0.43',
   )
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt
index efdef90a791..a9c7b5f4c41 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardFragment.kt
@@ -7,7 +7,6 @@ import android.view.View
 import android.view.ViewGroup
 import org.oppia.app.R
 import org.oppia.app.fragment.InjectableDialogFragment
-import org.oppia.domain.topic.TEST_SKILL_ID_2
 import javax.inject.Inject
 
 private const val KEY_SKILL_ID = "SKILL_ID"
@@ -44,8 +43,8 @@ class ConceptCardFragment : InjectableDialogFragment() {
 
   override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
     super.onCreateView(inflater, container, savedInstanceState)
-    val args = checkNotNull(arguments) { "Expected arguments to be pass to ConceptCardFragment" }
-    val skillId = args.getString(KEY_SKILL_ID, TEST_SKILL_ID_2)
+    val args = checkNotNull(arguments) { "Expected arguments to be passed to ConceptCardFragment" }
+    val skillId = checkNotNull(args.getString(KEY_SKILL_ID)) { "Expected skillId to be passed to ConceptCardFragment" }
     return conceptCardPresenter.handleCreateView(inflater, container, skillId)
   }
 
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
index a84d39732df..7b70abf9c6c 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/ConceptCardPresenter.kt
@@ -5,10 +5,9 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.DialogFragment
 import androidx.fragment.app.Fragment
-import androidx.recyclerview.widget.LinearLayoutManager
 import org.oppia.app.R
 import org.oppia.app.databinding.ConceptCardExampleViewBinding
-import org.oppia.app.databinding.ConceptcardFragmentBinding
+import org.oppia.app.databinding.ConceptCardFragmentBinding
 import org.oppia.app.fragment.FragmentScope
 import org.oppia.app.model.SubtitledHtml
 import org.oppia.app.recyclerview.BindableAdapter
@@ -26,14 +25,13 @@ class ConceptCardPresenter @Inject constructor(
   fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?, skillId: String): View? {
     val viewModel = getConceptCardViewModel()
     viewModel.setSkillId(skillId)
-    val binding = ConceptcardFragmentBinding.inflate(inflater, container, /* attachToRoot= */ false)
+    val binding = ConceptCardFragmentBinding.inflate(inflater, container, /* attachToRoot= */ false)
     binding.conceptCardToolbar.setNavigationIcon(R.drawable.ic_close_white_24dp)
     binding.conceptCardToolbar.setNavigationOnClickListener {
       (fragment as? DialogFragment)?.dismiss()
     }
     binding.workedExamples.apply {
       adapter = createRecyclerViewAdapter()
-      layoutManager = LinearLayoutManager(context)
     }
 
     binding.let {
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt
index e4dff578f1f..24b6055970c 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivity.kt
@@ -4,9 +4,10 @@ import android.os.Bundle
 import org.oppia.app.activity.InjectableAppCompatActivity
 import javax.inject.Inject
 
+/** Test Activity used for testing ConceptCardFragment */
 class ConceptCardFragmentTestActivity : InjectableAppCompatActivity() {
 
-  @Inject lateinit var conceptCardFragmentTestActivityController: ConceptCardFragmentTestActivityController
+  @Inject lateinit var conceptCardFragmentTestActivityController: ConceptCardFragmentTestActivityPresenter
 
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
diff --git a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityPresenter.kt
similarity index 58%
rename from app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
rename to app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityPresenter.kt
index 4960ad636e1..68d16f32bf4 100644
--- a/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityController.kt
+++ b/app/src/main/java/org/oppia/app/topic/conceptcard/testing/ConceptCardFragmentTestActivityPresenter.kt
@@ -4,15 +4,21 @@ import androidx.appcompat.app.AppCompatActivity
 import kotlinx.android.synthetic.main.concept_card_fragment_test_activity.*
 import org.oppia.app.R
 import org.oppia.app.topic.conceptcard.ConceptCardFragment
+import org.oppia.domain.topic.TEST_SKILL_ID_1
 import org.oppia.domain.topic.TEST_SKILL_ID_2
 import javax.inject.Inject
 
 private const val TAG_CONCEPT_CARD_DIALOG = "CONCEPT_CARD_DIALOG"
 
-class ConceptCardFragmentTestActivityController @Inject constructor(private val activity: AppCompatActivity) {
+/** The presenter for [ConceptCardFragmentTestActivity] */
+class ConceptCardFragmentTestActivityPresenter @Inject constructor(private val activity: AppCompatActivity) {
   fun handleOnCreate() {
     activity.setContentView(R.layout.concept_card_fragment_test_activity)
-    activity.open_dialog.setOnClickListener {
+    activity.open_dialog_1.setOnClickListener {
+      val frag = ConceptCardFragment.newInstance(TEST_SKILL_ID_1)
+      frag.showNow(activity.supportFragmentManager, TAG_CONCEPT_CARD_DIALOG)
+    }
+    activity.open_dialog_2.setOnClickListener {
       val frag = ConceptCardFragment.newInstance(TEST_SKILL_ID_2)
       frag.showNow(activity.supportFragmentManager, TAG_CONCEPT_CARD_DIALOG)
     }
diff --git a/app/src/main/res/layout/concept_card_example_view.xml b/app/src/main/res/layout/concept_card_example_view.xml
index 0fae774ed55..a903c7e0c76 100644
--- a/app/src/main/res/layout/concept_card_example_view.xml
+++ b/app/src/main/res/layout/concept_card_example_view.xml
@@ -19,4 +19,4 @@
       android:textColor="@android:color/black"
       android:text="@{subtitledHtml.getHtml()}"/>
   </androidx.constraintlayout.widget.ConstraintLayout>
-</layout>
\ No newline at end of file
+</layout>
diff --git a/app/src/main/res/layout/conceptcard_fragment.xml b/app/src/main/res/layout/concept_card_fragment.xml
similarity index 99%
rename from app/src/main/res/layout/conceptcard_fragment.xml
rename to app/src/main/res/layout/concept_card_fragment.xml
index f998c0baf86..fe81eacd92b 100644
--- a/app/src/main/res/layout/conceptcard_fragment.xml
+++ b/app/src/main/res/layout/concept_card_fragment.xml
@@ -48,4 +48,4 @@
       </LinearLayout>
     </ScrollView>
   </androidx.constraintlayout.widget.ConstraintLayout>
-</layout>
\ No newline at end of file
+</layout>
diff --git a/app/src/main/res/layout/concept_card_fragment_test_activity.xml b/app/src/main/res/layout/concept_card_fragment_test_activity.xml
index 63a60b277ce..8505adfd9d1 100644
--- a/app/src/main/res/layout/concept_card_fragment_test_activity.xml
+++ b/app/src/main/res/layout/concept_card_fragment_test_activity.xml
@@ -1,15 +1,14 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout android:layout_height="match_parent"
+<LinearLayout
+  android:layout_height="match_parent"
   android:layout_width="match_parent"
-  xmlns:android="http://schemas.android.com/apk/res/android"
-  xmlns:app="http://schemas.android.com/apk/res-auto">
+  xmlns:android="http://schemas.android.com/apk/res/android">
   <Button
-    android:id="@+id/open_dialog"
+    android:id="@+id/open_dialog_1"
     android:layout_width="wrap_content"
-    android:layout_height="wrap_content"
-    android:text="Open Concept Card Dialog"
-    app:layout_constraintTop_toTopOf="parent"
-    app:layout_constraintBottom_toBottomOf="parent"
-    app:layout_constraintStart_toStartOf="parent"
-    app:layout_constraintEnd_toEndOf="parent"/>
-</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
+    android:layout_height="wrap_content" />
+  <Button
+    android:id="@+id/open_dialog_2"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content" />
+</LinearLayout>
diff --git a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
index 1cb8ff5809e..794e1ad607c 100644
--- a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
+++ b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
@@ -9,12 +9,14 @@ import androidx.test.espresso.assertion.ViewAssertions.matches
 import androidx.test.espresso.matcher.ViewMatchers.withId
 import androidx.test.espresso.matcher.ViewMatchers.withText
 import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.rule.ActivityTestRule
 import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
 import dagger.BindsInstance
 import dagger.Component
 import dagger.Module
 import dagger.Provides
 import kotlinx.coroutines.CoroutineDispatcher
+import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.oppia.app.R
@@ -27,18 +29,46 @@ import javax.inject.Singleton
 @RunWith(AndroidJUnit4::class)
 class ConceptCardFragmentTest {
 
+  //@Rule
+  //val activityTestRule = ActivityTestRule(ConceptCardFragmentTestActivity::class.java)
+
+  @Test
+  fun testConceptCardFragment_openDialogFragmentWithSkill1_explanationIsDisplayed() {
+    ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
+      Espresso.onView(withId(R.id.open_dialog_1)).perform(click())
+      Espresso.onView(withId(R.id.explanation)).check(matches(withText("Explanation with <b>rich text</b>.")))
+    }
+  }
+
+  @Test
+  fun testConceptCardFragment_openDialogFragmentWithSkill1_workedExamplesAreDisplayed() {
+    ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
+      Espresso.onView(withId(R.id.open_dialog_1)).perform(click())
+      Espresso.onView(withText("Worked example with <i>rich text</i>.")).check(matches(isDisplayed()))
+    }
+  }
+
   @Test
-  fun testConceptCardFragment_openDialogFragment_explanationIsDisplayed() {
+  fun testConceptCardFragment_openDialogFragmentWithSkill2_explanationIsDisplayed() {
     ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
-      Espresso.onView(withId(R.id.open_dialog)).perform(click())
+      Espresso.onView(withId(R.id.open_dialog_2)).perform(click())
       Espresso.onView(withId(R.id.explanation)).check(matches(withText("Explanation without rich text.")))
     }
   }
 
   @Test
-  fun testConceptCardFragment_openDialogFragment_workedExamplesIsDisplayed() {
+  fun testConceptCardFragment_openDialogFragmentWithSkill2_workedExamplesAreDisplayed() {
+    ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
+      Espresso.onView(withId(R.id.open_dialog_2)).perform(click())
+      Espresso.onView(withText("Worked example without rich text.")).check(matches(isDisplayed()))
+      Espresso.onView(withText("Second worked example.")).check(matches(isDisplayed()))
+    }
+  }
+
+  @Test
+  fun testConceptCardFragment_openDialogFragmentWithSkill2_afterConfigurationChange_workedExamplesAreDisplayed() {
     ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
-      Espresso.onView(withId(R.id.open_dialog)).perform(click())
+      Espresso.onView(withId(R.id.open_dialog_2)).perform(click())
       Espresso.onView(withText("Worked example without rich text.")).check(matches(isDisplayed()))
       Espresso.onView(withText("Second worked example.")).check(matches(isDisplayed()))
     }

From e73215b9e43f325fb3e3ef1fdc0fde646b4a387e Mon Sep 17 00:00:00 2001
From: James Xu <jamesxu@umich.edu>
Date: Wed, 2 Oct 2019 11:33:40 -0700
Subject: [PATCH 08/14] Fixed test cases with ActivityTestRule

---
 app/build.gradle                              |  1 +
 .../conceptcard/ConceptCardFragmentTest.kt    | 41 ++++++++-----------
 2 files changed, 17 insertions(+), 25 deletions(-)

diff --git a/app/build.gradle b/app/build.gradle
index 17cfabcfe3a..3f5f25853f1 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -71,6 +71,7 @@ dependencies {
       'androidx.test:core:1.2.0',
       'androidx.test.espresso:espresso-core:3.2.0',
       'androidx.test.ext:junit:1.1.1',
+      'androidx.test:rules:1.2.0',
       'com.google.truth:truth:0.43',
       'org.robolectric:robolectric:4.3',
   )
diff --git a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
index 794e1ad607c..7690fff976b 100644
--- a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
+++ b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
@@ -2,7 +2,7 @@ package org.oppia.app.player.audio
 
 import android.app.Application
 import android.content.Context
-import androidx.test.core.app.ActivityScenario
+import android.content.pm.ActivityInfo
 import androidx.test.espresso.Espresso
 import androidx.test.espresso.action.ViewActions.click
 import androidx.test.espresso.assertion.ViewAssertions.matches
@@ -29,49 +29,40 @@ import javax.inject.Singleton
 @RunWith(AndroidJUnit4::class)
 class ConceptCardFragmentTest {
 
-  //@Rule
-  //val activityTestRule = ActivityTestRule(ConceptCardFragmentTestActivity::class.java)
+  @get:Rule
+  val activityTestRule = ActivityTestRule(ConceptCardFragmentTestActivity::class.java)
 
   @Test
   fun testConceptCardFragment_openDialogFragmentWithSkill1_explanationIsDisplayed() {
-    ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
-      Espresso.onView(withId(R.id.open_dialog_1)).perform(click())
-      Espresso.onView(withId(R.id.explanation)).check(matches(withText("Explanation with <b>rich text</b>.")))
-    }
+    Espresso.onView(withId(R.id.open_dialog_1)).perform(click())
+    Espresso.onView(withId(R.id.explanation)).check(matches(withText("Explanation with <b>rich text</b>.")))
   }
 
   @Test
   fun testConceptCardFragment_openDialogFragmentWithSkill1_workedExamplesAreDisplayed() {
-    ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
-      Espresso.onView(withId(R.id.open_dialog_1)).perform(click())
-      Espresso.onView(withText("Worked example with <i>rich text</i>.")).check(matches(isDisplayed()))
-    }
+    Espresso.onView(withId(R.id.open_dialog_1)).perform(click())
+    Espresso.onView(withText("Worked example with <i>rich text</i>.")).check(matches(isDisplayed()))
   }
 
   @Test
   fun testConceptCardFragment_openDialogFragmentWithSkill2_explanationIsDisplayed() {
-    ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
-      Espresso.onView(withId(R.id.open_dialog_2)).perform(click())
-      Espresso.onView(withId(R.id.explanation)).check(matches(withText("Explanation without rich text.")))
-    }
+    Espresso.onView(withId(R.id.open_dialog_2)).perform(click())
+    Espresso.onView(withId(R.id.explanation)).check(matches(withText("Explanation without rich text.")))
   }
 
   @Test
   fun testConceptCardFragment_openDialogFragmentWithSkill2_workedExamplesAreDisplayed() {
-    ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
-      Espresso.onView(withId(R.id.open_dialog_2)).perform(click())
-      Espresso.onView(withText("Worked example without rich text.")).check(matches(isDisplayed()))
-      Espresso.onView(withText("Second worked example.")).check(matches(isDisplayed()))
-    }
+    Espresso.onView(withId(R.id.open_dialog_2)).perform(click())
+    Espresso.onView(withText("Worked example without rich text.")).check(matches(isDisplayed()))
+    Espresso.onView(withText("Second worked example.")).check(matches(isDisplayed()))
   }
 
   @Test
   fun testConceptCardFragment_openDialogFragmentWithSkill2_afterConfigurationChange_workedExamplesAreDisplayed() {
-    ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java).use {
-      Espresso.onView(withId(R.id.open_dialog_2)).perform(click())
-      Espresso.onView(withText("Worked example without rich text.")).check(matches(isDisplayed()))
-      Espresso.onView(withText("Second worked example.")).check(matches(isDisplayed()))
-    }
+    Espresso.onView(withId(R.id.open_dialog_2)).perform(click())
+    activityTestRule.activity.requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE
+    Espresso.onView(withText("Worked example without rich text.")).check(matches(isDisplayed()))
+    Espresso.onView(withText("Second worked example.")).check(matches(isDisplayed()))
   }
 
   @Module

From 3b30f1c6e8b674aca2adfa1c1a841f7b10f28fd7 Mon Sep 17 00:00:00 2001
From: Ben Henning <henning.benmax@gmail.com>
Date: Mon, 7 Oct 2019 16:49:43 -0700
Subject: [PATCH 09/14] Undo unnecessary removal of optional modifier for
 onAttach callback.

---
 app/src/main/java/org/oppia/app/fragment/InjectableFragment.kt  | 2 +-
 app/src/main/java/org/oppia/app/home/HomeFragment.kt            | 2 +-
 app/src/main/java/org/oppia/app/player/audio/AudioFragment.kt   | 2 +-
 .../org/oppia/app/player/exploration/ExplorationFragment.kt     | 2 +-
 app/src/main/java/org/oppia/app/player/state/StateFragment.kt   | 2 +-
 .../java/org/oppia/app/testing/BindableAdapterTestFragment.kt   | 2 +-
 6 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/app/src/main/java/org/oppia/app/fragment/InjectableFragment.kt b/app/src/main/java/org/oppia/app/fragment/InjectableFragment.kt
index 8042a88d3cc..25c3628f07a 100644
--- a/app/src/main/java/org/oppia/app/fragment/InjectableFragment.kt
+++ b/app/src/main/java/org/oppia/app/fragment/InjectableFragment.kt
@@ -16,7 +16,7 @@ abstract class InjectableFragment: Fragment() {
    */
   lateinit var fragmentComponent: FragmentComponent
 
-  override fun onAttach(context: Context) {
+  override fun onAttach(context: Context?) {
     super.onAttach(context)
     fragmentComponent = (requireActivity() as InjectableAppCompatActivity).createFragmentComponent(this)
   }
diff --git a/app/src/main/java/org/oppia/app/home/HomeFragment.kt b/app/src/main/java/org/oppia/app/home/HomeFragment.kt
index 66a537947a4..e3bc454853f 100644
--- a/app/src/main/java/org/oppia/app/home/HomeFragment.kt
+++ b/app/src/main/java/org/oppia/app/home/HomeFragment.kt
@@ -12,7 +12,7 @@ import javax.inject.Inject
 class HomeFragment : InjectableFragment() {
   @Inject lateinit var homeFragmentController: HomeFragmentController
 
-  override fun onAttach(context: Context) {
+  override fun onAttach(context: Context?) {
     super.onAttach(context)
     fragmentComponent.inject(this)
   }
diff --git a/app/src/main/java/org/oppia/app/player/audio/AudioFragment.kt b/app/src/main/java/org/oppia/app/player/audio/AudioFragment.kt
index 457b354f2de..9968287b963 100755
--- a/app/src/main/java/org/oppia/app/player/audio/AudioFragment.kt
+++ b/app/src/main/java/org/oppia/app/player/audio/AudioFragment.kt
@@ -16,7 +16,7 @@ class AudioFragment : InjectableFragment(), LanguageInterface {
   lateinit var audioFragmentPresenter: AudioFragmentPresenter
   private var selectedLanguageCode: String = "en"
 
-  override fun onAttach(context: Context) {
+  override fun onAttach(context: Context?) {
     super.onAttach(context)
     fragmentComponent.inject(this)
   }
diff --git a/app/src/main/java/org/oppia/app/player/exploration/ExplorationFragment.kt b/app/src/main/java/org/oppia/app/player/exploration/ExplorationFragment.kt
index a60850d21cb..337112eee6c 100755
--- a/app/src/main/java/org/oppia/app/player/exploration/ExplorationFragment.kt
+++ b/app/src/main/java/org/oppia/app/player/exploration/ExplorationFragment.kt
@@ -12,7 +12,7 @@ import javax.inject.Inject
 class ExplorationFragment : InjectableFragment() {
   @Inject lateinit var explorationFragmentPresenter: ExplorationFragmentPresenter
 
-  override fun onAttach(context: Context) {
+  override fun onAttach(context: Context?) {
     super.onAttach(context)
     fragmentComponent.inject(this)
   }
diff --git a/app/src/main/java/org/oppia/app/player/state/StateFragment.kt b/app/src/main/java/org/oppia/app/player/state/StateFragment.kt
index 7c3d3503595..5d0cf9b796a 100755
--- a/app/src/main/java/org/oppia/app/player/state/StateFragment.kt
+++ b/app/src/main/java/org/oppia/app/player/state/StateFragment.kt
@@ -14,7 +14,7 @@ class StateFragment : InjectableFragment(), CellularDataInterface {
 
   @Inject lateinit var stateFragmentPresenter: StateFragmentPresenter
 
-  override fun onAttach(context: Context) {
+  override fun onAttach(context: Context?) {
     super.onAttach(context)
     fragmentComponent.inject(this)
   }
diff --git a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragment.kt b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragment.kt
index 0a9c477dc1a..4876e16dbd0 100644
--- a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragment.kt
+++ b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragment.kt
@@ -16,7 +16,7 @@ class BindableAdapterTestFragment: InjectableFragment() {
   @Inject
   lateinit var bindableAdapterTestFragmentPresenter: BindableAdapterTestFragmentPresenter
 
-  override fun onAttach(context: Context) {
+  override fun onAttach(context: Context?) {
     super.onAttach(context)
     fragmentComponent.inject(this)
   }

From 92f89313c25f6b97f4c6d2cac7a7a972a81d750a Mon Sep 17 00:00:00 2001
From: Ben Henning <henning.benmax@gmail.com>
Date: Mon, 7 Oct 2019 18:46:32 -0700
Subject: [PATCH 10/14] Fix and finish tests for BindableAdapter.

---
 app/build.gradle                              |   3 +-
 .../testing/BindableAdapterTestActivity.kt    |   6 +-
 .../BindableAdapterTestFragmentPresenter.kt   |   3 +-
 .../testing/BindableAdapterTestViewModel.kt   |   3 +-
 .../app/topic/train/SkillSelectionAdapter.kt  |   2 +-
 app/src/main/res/layout/test_activity.xml     |   7 +
 app/src/main/res/layout/test_fragment.xml     |   2 +-
 ...test_text_view_for_int_no_data_binding.xml |   8 +
 ...st_text_view_for_int_with_data_binding.xml |  15 ++
 ...t_text_view_for_string_no_data_binding.xml |   8 +
 ...text_view_for_string_with_data_binding.xml |  15 ++
 .../layout/test_text_view_no_data_binding.xml |   6 -
 .../app/recyclerview/BindableAdapterTest.kt   | 248 ++++++++++++++++--
 model/src/main/proto/example.proto            |   7 +
 14 files changed, 303 insertions(+), 30 deletions(-)
 create mode 100644 app/src/main/res/layout/test_activity.xml
 create mode 100644 app/src/main/res/layout/test_text_view_for_int_no_data_binding.xml
 create mode 100644 app/src/main/res/layout/test_text_view_for_int_with_data_binding.xml
 create mode 100644 app/src/main/res/layout/test_text_view_for_string_no_data_binding.xml
 create mode 100644 app/src/main/res/layout/test_text_view_for_string_with_data_binding.xml
 delete mode 100644 app/src/main/res/layout/test_text_view_no_data_binding.xml

diff --git a/app/build.gradle b/app/build.gradle
index a86b9c404e8..6b51c81a76d 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -73,6 +73,7 @@ dependencies {
   testImplementation(
       'androidx.test:core:1.2.0',
       'androidx.test.espresso:espresso-core:3.2.0',
+      'androidx.test.espresso:espresso-intents:3.1.0',
       'androidx.test.ext:junit:1.1.1',
       'com.google.truth:truth:0.43',
       'org.robolectric:robolectric:4.3',
@@ -80,10 +81,10 @@ dependencies {
   androidTestImplementation(
       'androidx.test:core:1.2.0',
       'androidx.test.espresso:espresso-core:3.2.0',
+      'androidx.test.espresso:espresso-intents:3.1.0',
       'androidx.test.ext:junit:1.1.1',
       'androidx.test:runner:1.2.0',
       'com.google.truth:truth:0.43',
-      'androidx.test.espresso:espresso-intents:3.1.0',
   )
   androidTestUtil(
       'androidx.test:orchestrator:1.2.0',
diff --git a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestActivity.kt b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestActivity.kt
index bec31a709e4..148f7a84030 100644
--- a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestActivity.kt
+++ b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestActivity.kt
@@ -1,6 +1,7 @@
 package org.oppia.app.testing
 
 import android.os.Bundle
+import org.oppia.app.R
 import org.oppia.app.activity.InjectableAppCompatActivity
 
 // TODO(#59): Make this activity only included in relevant tests instead of all prod builds.
@@ -9,6 +10,9 @@ class BindableAdapterTestActivity: InjectableAppCompatActivity() {
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
     activityComponent.inject(this)
-    supportFragmentManager.beginTransaction().add(BindableAdapterTestFragment(), BINDABLE_TEST_FRAGMENT_TAG).commitNow()
+    setContentView(R.layout.test_activity)
+    supportFragmentManager.beginTransaction()
+      .add(R.id.test_fragment_placeholder, BindableAdapterTestFragment(), BINDABLE_TEST_FRAGMENT_TAG)
+      .commitNow()
   }
 }
diff --git a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragmentPresenter.kt b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragmentPresenter.kt
index c066abadcb5..5a6bd27c41a 100644
--- a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragmentPresenter.kt
+++ b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestFragmentPresenter.kt
@@ -6,6 +6,7 @@ import android.view.ViewGroup
 import androidx.annotation.VisibleForTesting
 import androidx.fragment.app.Fragment
 import org.oppia.app.databinding.TestFragmentBinding
+import org.oppia.app.model.TestModel
 import org.oppia.app.recyclerview.BindableAdapter
 import org.oppia.app.viewmodel.ViewModelProvider
 import javax.inject.Inject
@@ -22,7 +23,7 @@ class BindableAdapterTestFragmentPresenter @Inject constructor(
   companion object {
     // TODO(#59): Move away from this fragile static testing state by leveraging a test-only DI graph that can be
     //  configured within tests to provide the bindable adapter to be used by this presenter.
-    var testBindableAdapter: BindableAdapter<String>? = null
+    var testBindableAdapter: BindableAdapter<TestModel>? = null
   }
 
   fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?): View? {
diff --git a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestViewModel.kt b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestViewModel.kt
index 3f695c4b2c6..175657fdda4 100644
--- a/app/src/main/java/org/oppia/app/testing/BindableAdapterTestViewModel.kt
+++ b/app/src/main/java/org/oppia/app/testing/BindableAdapterTestViewModel.kt
@@ -3,11 +3,12 @@ package org.oppia.app.testing
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import org.oppia.app.fragment.FragmentScope
+import org.oppia.app.model.TestModel
 import javax.inject.Inject
 
 // TODO(#59): Make this view model only included in relevant tests instead of all prod builds.
 /** A [ViewModel] for testing the bindable RecyclerView adapter. */
 @FragmentScope
 class BindableAdapterTestViewModel @Inject constructor(): ViewModel() {
-  val dataListLiveData = MutableLiveData<List<String>>()
+  val dataListLiveData = MutableLiveData<List<TestModel>>()
 }
diff --git a/app/src/main/java/org/oppia/app/topic/train/SkillSelectionAdapter.kt b/app/src/main/java/org/oppia/app/topic/train/SkillSelectionAdapter.kt
index 7b45fbef6bd..56c50a709ee 100644
--- a/app/src/main/java/org/oppia/app/topic/train/SkillSelectionAdapter.kt
+++ b/app/src/main/java/org/oppia/app/topic/train/SkillSelectionAdapter.kt
@@ -10,7 +10,7 @@ import kotlinx.android.synthetic.main.topic_train_skill_view.view.*
 import org.oppia.app.R
 import org.oppia.app.databinding.TopicTrainSkillViewBinding
 
-// TODO(#172): Make use of generic data-binding-enabled RecyclerView adapter.
+// TODO(#216): Make use of generic data-binding-enabled RecyclerView adapter.
 /** Adapter to bind skills to [RecyclerView] inside [TopicTrainFragment]. */
 class SkillSelectionAdapter(
   private val skillList: List<String>,
diff --git a/app/src/main/res/layout/test_activity.xml b/app/src/main/res/layout/test_activity.xml
new file mode 100644
index 00000000000..7f8c80ba1d7
--- /dev/null
+++ b/app/src/main/res/layout/test_activity.xml
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- TODO(#59): Make this layout only accessible to tests. -->
+<FrameLayout
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  android:id="@+id/test_fragment_placeholder"
+  android:layout_width="match_parent"
+  android:layout_height="match_parent" />
diff --git a/app/src/main/res/layout/test_fragment.xml b/app/src/main/res/layout/test_fragment.xml
index b2b1e67b68d..0b3df3d560d 100644
--- a/app/src/main/res/layout/test_fragment.xml
+++ b/app/src/main/res/layout/test_fragment.xml
@@ -9,7 +9,7 @@
 
   <androidx.recyclerview.widget.RecyclerView
     android:id="@+id/test_recycler_view"
-    android:layout_width="wrap_content"
+    android:layout_width="match_parent"
     android:layout_height="wrap_content"
     app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
     app:data="@{viewModel.dataListLiveData}"/>
diff --git a/app/src/main/res/layout/test_text_view_for_int_no_data_binding.xml b/app/src/main/res/layout/test_text_view_for_int_no_data_binding.xml
new file mode 100644
index 00000000000..ad1ac2a02ea
--- /dev/null
+++ b/app/src/main/res/layout/test_text_view_for_int_no_data_binding.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- TODO(#59): Make this layout only accessible to tests. -->
+<TextView
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  android:id="@+id/text_view_for_int_no_data_binding"
+  android:textColor="@color/colorPrimaryDark"
+  android:layout_width="wrap_content"
+  android:layout_height="wrap_content"/>
diff --git a/app/src/main/res/layout/test_text_view_for_int_with_data_binding.xml b/app/src/main/res/layout/test_text_view_for_int_with_data_binding.xml
new file mode 100644
index 00000000000..915157d9b2c
--- /dev/null
+++ b/app/src/main/res/layout/test_text_view_for_int_with_data_binding.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- TODO(#59): Make this layout only accessible to tests. -->
+<layout
+  xmlns:android="http://schemas.android.com/apk/res/android">
+  <data>
+    <variable name="viewModel" type="org.oppia.app.model.TestModel"/>
+  </data>
+
+  <TextView
+    android:id="@+id/text_view_for_int_no_data_binding"
+    android:textColor="@color/colorPrimaryDark"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:text="@{`Value: ` + viewModel.intValue}"/>
+</layout>
diff --git a/app/src/main/res/layout/test_text_view_for_string_no_data_binding.xml b/app/src/main/res/layout/test_text_view_for_string_no_data_binding.xml
new file mode 100644
index 00000000000..ce50bcd6ba7
--- /dev/null
+++ b/app/src/main/res/layout/test_text_view_for_string_no_data_binding.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- TODO(#59): Make this layout only accessible to tests. -->
+<TextView
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  android:id="@+id/text_view_for_string_no_data_binding"
+  android:textColor="@color/colorPrimary"
+  android:layout_width="wrap_content"
+  android:layout_height="wrap_content"/>
diff --git a/app/src/main/res/layout/test_text_view_for_string_with_data_binding.xml b/app/src/main/res/layout/test_text_view_for_string_with_data_binding.xml
new file mode 100644
index 00000000000..8031f91e2f7
--- /dev/null
+++ b/app/src/main/res/layout/test_text_view_for_string_with_data_binding.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- TODO(#59): Make this layout only accessible to tests. -->
+<layout
+xmlns:android="http://schemas.android.com/apk/res/android">
+<data>
+  <variable name="viewModel" type="org.oppia.app.model.TestModel"/>
+</data>
+
+<TextView
+  android:id="@+id/text_view_for_string_no_data_binding"
+  android:textColor="@color/colorPrimary"
+  android:layout_width="wrap_content"
+  android:layout_height="wrap_content"
+  android:text="@{viewModel.strValue}"/>
+</layout>
diff --git a/app/src/main/res/layout/test_text_view_no_data_binding.xml b/app/src/main/res/layout/test_text_view_no_data_binding.xml
deleted file mode 100644
index c5de925f746..00000000000
--- a/app/src/main/res/layout/test_text_view_no_data_binding.xml
+++ /dev/null
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<TextView
-  xmlns:android="http://schemas.android.com/apk/res/android"
-  android:id="@+id/text_view_no_data_binding"
-  android:layout_width="match_parent"
-  android:layout_height="match_parent"/>
diff --git a/app/src/sharedTest/java/org/oppia/app/recyclerview/BindableAdapterTest.kt b/app/src/sharedTest/java/org/oppia/app/recyclerview/BindableAdapterTest.kt
index 948022aa381..39423e79895 100644
--- a/app/src/sharedTest/java/org/oppia/app/recyclerview/BindableAdapterTest.kt
+++ b/app/src/sharedTest/java/org/oppia/app/recyclerview/BindableAdapterTest.kt
@@ -11,6 +11,7 @@ import androidx.test.espresso.Espresso.onIdle
 import androidx.test.espresso.Espresso.onView
 import androidx.test.espresso.assertion.ViewAssertions.matches
 import androidx.test.espresso.matcher.ViewMatchers.withId
+import androidx.test.espresso.matcher.ViewMatchers.withSubstring
 import androidx.test.espresso.matcher.ViewMatchers.withText
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.google.common.truth.Truth.assertThat
@@ -19,18 +20,30 @@ import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.oppia.app.R
+import org.oppia.app.model.TestModel
 import org.oppia.app.testing.BINDABLE_TEST_FRAGMENT_TAG
 import org.oppia.app.testing.BindableAdapterTestActivity
 import org.oppia.app.testing.BindableAdapterTestFragment
 import org.oppia.app.testing.BindableAdapterTestFragmentPresenter
 import org.oppia.app.testing.BindableAdapterTestViewModel
-
-const val ITEM_0 = "Item 0"
-const val ITEM_1 = "Item 1"
+import androidx.test.espresso.matcher.BoundedMatcher
+import android.view.View
+import org.hamcrest.Description
+import org.hamcrest.Matcher
+import org.oppia.app.databinding.TestTextViewForIntWithDataBindingBinding
+import org.oppia.app.databinding.TestTextViewForStringWithDataBindingBinding
 
 /** Tests for [BindableAdapter]. */
 @RunWith(AndroidJUnit4::class)
 class BindableAdapterTest {
+  companion object {
+    private val STR_VALUE_0 = TestModel.newBuilder().setStrValue("Item 0").build()
+    private val STR_VALUE_1 = TestModel.newBuilder().setStrValue("Item 1").build()
+    private val STR_VALUE_2 = TestModel.newBuilder().setStrValue("Item 2").build()
+    private val INT_VALUE_0 = TestModel.newBuilder().setIntValue(17).build()
+    private val INT_VALUE_1 = TestModel.newBuilder().setIntValue(42).build()
+  }
+
   @Before
   fun setUp() {
     // Ensure that the bindable fragment's test state is properly reset each time.
@@ -66,40 +79,218 @@ class BindableAdapterTest {
     ActivityScenario.launch(BindableAdapterTestActivity::class.java).use { scenario ->
       scenario.onActivity { activity ->
         val liveData = getRecyclerViewListLiveData(activity)
-        liveData.value = listOf(ITEM_0)
-        onIdle()
+        liveData.value = listOf(STR_VALUE_0)
+      }
+      safelyWaitUntilIdle()
+
+      scenario.onActivity { activity ->
+        val recyclerView: RecyclerView = getTestFragment(activity).view!!.findViewById(R.id.test_recycler_view)
+        assertThat(recyclerView.childCount).isEqualTo(1)
+      }
+      // Perform onView() verification off the the main thread to avoid deadlocking.
+      onView(withId(R.id.test_recycler_view)).check(matches(atPosition(0, withText(STR_VALUE_0.strValue))))
+    }
+  }
+
+  @Test
+  fun testBindableAdapter_withOneViewType_setMultipleItems_automaticallyBinds() {
+    // Set up the adapter to be used for this test.
+    BindableAdapterTestFragmentPresenter.testBindableAdapter =
+      createSingleViewTypeNoDataBindingBindableAdapter()
+
+    ActivityScenario.launch(BindableAdapterTestActivity::class.java).use { scenario ->
+      scenario.onActivity { activity ->
+        val liveData = getRecyclerViewListLiveData(activity)
+        liveData.value = listOf(STR_VALUE_1, STR_VALUE_0, STR_VALUE_2)
+      }
+      safelyWaitUntilIdle()
+
+      scenario.onActivity { activity ->
+        val recyclerView: RecyclerView = getTestFragment(activity).view!!.findViewById(R.id.test_recycler_view)
+        assertThat(recyclerView.childCount).isEqualTo(3)
+      }
+      onView(withId(R.id.test_recycler_view)).check(matches(atPosition(0, withText(STR_VALUE_1.strValue))))
+      onView(withId(R.id.test_recycler_view)).check(matches(atPosition(1, withText(STR_VALUE_0.strValue))))
+      onView(withId(R.id.test_recycler_view)).check(matches(atPosition(2, withText(STR_VALUE_2.strValue))))
+    }
+  }
+
+  @Test
+  fun testBindableAdapter_withTwoViewTypes_setItems_autoBindsCorrectItemsPerTypes() {
+    // Set up the adapter to be used for this test.
+    BindableAdapterTestFragmentPresenter.testBindableAdapter =
+      createMultiViewTypeNoDataBindingBindableAdapter()
+
+    ActivityScenario.launch(BindableAdapterTestActivity::class.java).use { scenario ->
+      scenario.onActivity { activity ->
+        val liveData = getRecyclerViewListLiveData(activity)
+        liveData.value = listOf(STR_VALUE_1, INT_VALUE_0, INT_VALUE_1)
+      }
+      safelyWaitUntilIdle()
 
+      // Verify that all three values are bound in the correct order and with the correct values.
+      scenario.onActivity { activity ->
+        val recyclerView: RecyclerView = getTestFragment(activity).view!!.findViewById(R.id.test_recycler_view)
+        assertThat(recyclerView.childCount).isEqualTo(3)
+      }
+      onView(withId(R.id.test_recycler_view)).check(matches(atPosition(0, withText(STR_VALUE_1.strValue))))
+      onView(withId(R.id.test_recycler_view))
+        .check(matches(atPosition(1, withSubstring(INT_VALUE_0.intValue.toString()))))
+      onView(withId(R.id.test_recycler_view))
+        .check(matches(atPosition(2, withSubstring(INT_VALUE_1.intValue.toString()))))
+    }
+  }
+
+  @Test
+  fun testBindableAdapter_withOneDataBoundViewType_setItem_automaticallyBindsView() {
+    // Set up the adapter to be used for this test.
+    BindableAdapterTestFragmentPresenter.testBindableAdapter =
+      createSingleViewTypeWithDataBindingBindableAdapter()
+
+    ActivityScenario.launch(BindableAdapterTestActivity::class.java).use { scenario ->
+      scenario.onActivity { activity ->
+        val liveData = getRecyclerViewListLiveData(activity)
+        liveData.value = listOf(STR_VALUE_0)
+      }
+      safelyWaitUntilIdle()
+
+      scenario.onActivity { activity ->
         val recyclerView: RecyclerView = getTestFragment(activity).view!!.findViewById(R.id.test_recycler_view)
         assertThat(recyclerView.childCount).isEqualTo(1)
-//        onView(withId(R.id.text_view_no_data_binding)).check(matches(withText(ITEM_0)))
       }
+      // Perform onView() verification off the the main thread to avoid deadlocking.
+      onView(withId(R.id.test_recycler_view)).check(matches(atPosition(0, withText(STR_VALUE_0.strValue))))
     }
   }
 
-  // testBindableAdapter_withOneViewType_setMultipleItems_automaticallyBinds
-  // testBindableAdapter_withTwoViewTypes_setItems_autoBindsCorrectItemsPerTypes
-  // testBindableAdapter_withTwoViewTypes_setItems_autoBindsCorrectItemsPerTypes
+  @Test
+  fun testBindableAdapter_withTwoDataBoundViewTypes_setItems_autoBindsCorrectItemsPerTypes() {
+    // Set up the adapter to be used for this test.
+    BindableAdapterTestFragmentPresenter.testBindableAdapter =
+      createSingleViewTypeWithDataBindingBindableAdapter()
 
-  private fun createSingleViewTypeNoDataBindingBindableAdapter(): BindableAdapter<String> {
+    ActivityScenario.launch(BindableAdapterTestActivity::class.java).use { scenario ->
+      scenario.onActivity { activity ->
+        val liveData = getRecyclerViewListLiveData(activity)
+        liveData.value = listOf(STR_VALUE_1, STR_VALUE_0, STR_VALUE_2)
+      }
+      safelyWaitUntilIdle()
+
+      scenario.onActivity { activity ->
+        val recyclerView: RecyclerView = getTestFragment(activity).view!!.findViewById(R.id.test_recycler_view)
+        assertThat(recyclerView.childCount).isEqualTo(3)
+      }
+      onView(withId(R.id.test_recycler_view)).check(matches(atPosition(0, withText(STR_VALUE_1.strValue))))
+      onView(withId(R.id.test_recycler_view)).check(matches(atPosition(1, withText(STR_VALUE_0.strValue))))
+      onView(withId(R.id.test_recycler_view)).check(matches(atPosition(2, withText(STR_VALUE_2.strValue))))
+    }
+  }
+
+  @Test
+  fun testBindableAdapter_withPartiallyDataBoundViewTypes_setItems_autoBindsCorrectItemsPerTypes() {
+    // Set up the adapter to be used for this test.
+    BindableAdapterTestFragmentPresenter.testBindableAdapter =
+      createMultiViewTypeWithDataBindingBindableAdapter()
+
+    ActivityScenario.launch(BindableAdapterTestActivity::class.java).use { scenario ->
+      scenario.onActivity { activity ->
+        val liveData = getRecyclerViewListLiveData(activity)
+        liveData.value = listOf(STR_VALUE_1, INT_VALUE_0, INT_VALUE_1)
+      }
+      safelyWaitUntilIdle()
+
+      // Verify that all three values are bound in the correct order and with the correct values.
+      scenario.onActivity { activity ->
+        val recyclerView: RecyclerView = getTestFragment(activity).view!!.findViewById(R.id.test_recycler_view)
+        assertThat(recyclerView.childCount).isEqualTo(3)
+      }
+      onView(withId(R.id.test_recycler_view)).check(matches(atPosition(0, withText(STR_VALUE_1.strValue))))
+      onView(withId(R.id.test_recycler_view))
+        .check(matches(atPosition(1, withSubstring(INT_VALUE_0.intValue.toString()))))
+      onView(withId(R.id.test_recycler_view))
+        .check(matches(atPosition(2, withSubstring(INT_VALUE_1.intValue.toString()))))
+    }
+  }
+
+  private fun createSingleViewTypeNoDataBindingBindableAdapter(): BindableAdapter<TestModel> {
     return BindableAdapter.Builder
-      .newBuilder<String>()
+      .newBuilder<TestModel>()
       .registerViewBinder(
-        inflateView = this::inflateTextViewWithoutDataBinding,
-        bindView = this::bindTextViewWithoutDataBinding
+        inflateView = this::inflateTextViewForStringWithoutDataBinding,
+        bindView = this::bindTextViewForStringWithoutDataBinding
       )
       .build()
   }
 
-  private fun inflateTextViewWithoutDataBinding(viewGroup: ViewGroup): TextView {
+  private fun createSingleViewTypeWithDataBindingBindableAdapter(): BindableAdapter<TestModel> {
+    return BindableAdapter.Builder
+      .newBuilder<TestModel>()
+      .registerViewDataBinder(
+        inflateDataBinding = TestTextViewForStringWithDataBindingBinding::inflate,
+        setViewModel = TestTextViewForStringWithDataBindingBinding::setViewModel
+      )
+      .build()
+  }
+
+  private fun createMultiViewTypeNoDataBindingBindableAdapter(): BindableAdapter<TestModel> {
+    return BindableAdapter.Builder
+      .newBuilder<TestModel>()
+      .registerViewTypeComputer { value ->
+        value.modelTypeCase.number
+      }
+      .registerViewBinder(
+        viewType = TestModel.STR_VALUE_FIELD_NUMBER,
+        inflateView = this::inflateTextViewForStringWithoutDataBinding,
+        bindView = this::bindTextViewForStringWithoutDataBinding
+      )
+      .registerViewBinder(
+        viewType = TestModel.INT_VALUE_FIELD_NUMBER,
+        inflateView = this::inflateTextViewForIntWithoutDataBinding,
+        bindView = this::bindTextViewForIntWithoutDataBinding
+      )
+      .build()
+  }
+
+  private fun createMultiViewTypeWithDataBindingBindableAdapter(): BindableAdapter<TestModel> {
+    return BindableAdapter.Builder
+      .newBuilder<TestModel>()
+      .registerViewTypeComputer { value ->
+        value.modelTypeCase.number
+      }
+      .registerViewDataBinder(
+        viewType = TestModel.STR_VALUE_FIELD_NUMBER,
+        inflateDataBinding = TestTextViewForStringWithDataBindingBinding::inflate,
+        setViewModel = TestTextViewForStringWithDataBindingBinding::setViewModel
+      )
+      .registerViewDataBinder(
+        viewType = TestModel.INT_VALUE_FIELD_NUMBER,
+        inflateDataBinding = TestTextViewForIntWithDataBindingBinding::inflate,
+        setViewModel = TestTextViewForIntWithDataBindingBinding::setViewModel
+      )
+      .build()
+  }
+
+  private fun inflateTextViewForStringWithoutDataBinding(viewGroup: ViewGroup): TextView {
+    val inflater = LayoutInflater.from(ApplicationProvider.getApplicationContext())
+    return inflater.inflate(
+      R.layout.test_text_view_for_string_no_data_binding, viewGroup, /* attachToRoot= */ false) as TextView
+  }
+
+  private fun inflateTextViewForIntWithoutDataBinding(viewGroup: ViewGroup): TextView {
     val inflater = LayoutInflater.from(ApplicationProvider.getApplicationContext())
-    return inflater.inflate(R.layout.test_text_view_no_data_binding, viewGroup, /* attachToRoot= */ false) as TextView
+    return inflater.inflate(
+      R.layout.test_text_view_for_int_no_data_binding, viewGroup, /* attachToRoot= */ false) as TextView
   }
 
-  private fun bindTextViewWithoutDataBinding(textView: TextView, data: String) {
-    textView.text = data
+  private fun bindTextViewForStringWithoutDataBinding(textView: TextView, data: TestModel) {
+    textView.text = data.strValue
   }
 
-  private fun getRecyclerViewListLiveData(activity: BindableAdapterTestActivity): MutableLiveData<List<String>> {
+  private fun bindTextViewForIntWithoutDataBinding(textView: TextView, data: TestModel) {
+    textView.text = "Value: " + data.intValue
+  }
+
+  private fun getRecyclerViewListLiveData(activity: BindableAdapterTestActivity): MutableLiveData<List<TestModel>> {
     return getTestViewModel(activity).dataListLiveData
   }
 
@@ -114,4 +305,25 @@ class BindableAdapterTest {
   private fun getTestFragment(activity: BindableAdapterTestActivity): BindableAdapterTestFragment {
     return activity.supportFragmentManager.findFragmentByTag(BINDABLE_TEST_FRAGMENT_TAG) as BindableAdapterTestFragment
   }
+
+  private fun safelyWaitUntilIdle() {
+    // This must be done off the main thread for Espresso otherwise it deadlocks.
+    onIdle()
+  }
+
+  // TODO(#89): Move this to a consolidated test library.
+  // https://stackoverflow.com/a/34795431
+  private fun atPosition(position: Int, itemMatcher: Matcher<View>): Matcher<View> {
+    return object : BoundedMatcher<View, RecyclerView>(RecyclerView::class.java) {
+      override fun describeTo(description: Description) {
+        description.appendText("has item at position $position: ")
+        itemMatcher.describeTo(description)
+      }
+
+      override fun matchesSafely(view: RecyclerView): Boolean {
+        val viewHolder = view.findViewHolderForAdapterPosition(position) ?: return false
+        return itemMatcher.matches(viewHolder.itemView)
+      }
+    }
+  }
 }
diff --git a/model/src/main/proto/example.proto b/model/src/main/proto/example.proto
index 15e27e9a7b1..0c68a3d68b4 100644
--- a/model/src/main/proto/example.proto
+++ b/model/src/main/proto/example.proto
@@ -12,3 +12,10 @@ message UserAppHistory {
 message TestMessage {
   int32 version = 1;
 }
+
+message TestModel {
+  oneof model_type {
+    string str_value = 1;
+    int32 int_value = 2;
+  }
+}

From 2010347cf854734d0d1293ea2dcdd7826db3f843 Mon Sep 17 00:00:00 2001
From: Ben Henning <henning.benmax@gmail.com>
Date: Mon, 7 Oct 2019 18:47:51 -0700
Subject: [PATCH 11/14] Address review comment.

---
 app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt b/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt
index d6ef7563e4a..9adc551c08a 100644
--- a/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt
+++ b/app/src/main/java/org/oppia/app/recyclerview/BindableAdapter.kt
@@ -7,7 +7,7 @@ import androidx.databinding.ViewDataBinding
 import androidx.recyclerview.widget.RecyclerView
 import kotlin.reflect.KClass
 
-/** A function that returns the type of view that should can bind the specified data object. */
+/** A function that returns the type of view that can bind the specified data object. */
 typealias ComputeViewType<T> = (T) -> Int
 
 /**

From bb918686777f54502ca655b8f4595d1fc6cbe834 Mon Sep 17 00:00:00 2001
From: jamesxu <jamesxu@umich.edu>
Date: Thu, 10 Oct 2019 11:39:44 -0700
Subject: [PATCH 12/14] removed unnecessary import

---
 app/build.gradle | 1 -
 1 file changed, 1 deletion(-)

diff --git a/app/build.gradle b/app/build.gradle
index 95cf6a0ed81..8af27c63858 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -84,7 +84,6 @@ dependencies {
       'androidx.test.espresso:espresso-core:3.2.0',
       'androidx.test.espresso:espresso-intents:3.1.0',
       'androidx.test.ext:junit:1.1.1',
-      'androidx.test:rules:1.2.0',
       'androidx.test:runner:1.2.0',
       'com.google.truth:truth:0.43',
   )

From 47cea20509901c46629bbae3b4623357fa856122 Mon Sep 17 00:00:00 2001
From: James Xu <jamesxu@umich.edu>
Date: Fri, 11 Oct 2019 15:22:45 -0700
Subject: [PATCH 13/14] Tests now using activity scenario

---
 app/build.gradle                              |  1 -
 .../conceptcard/ConceptCardFragmentTest.kt    | 23 ++++++++++++-------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/app/build.gradle b/app/build.gradle
index 8af27c63858..6b51c81a76d 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -75,7 +75,6 @@ dependencies {
       'androidx.test.espresso:espresso-core:3.2.0',
       'androidx.test.espresso:espresso-intents:3.1.0',
       'androidx.test.ext:junit:1.1.1',
-      'androidx.test:rules:1.2.0',
       'com.google.truth:truth:0.43',
       'org.robolectric:robolectric:4.3',
   )
diff --git a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
index 089c59b81a2..cebbd40fcf6 100644
--- a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
+++ b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
@@ -1,22 +1,22 @@
-package org.oppia.app.topic.conceptcard
+package org.oppia.app.player.audio
 
 import android.app.Application
 import android.content.Context
-import android.content.pm.ActivityInfo
-import androidx.test.espresso.action.ViewActions.click
+import android.content.res.Configuration
+import androidx.test.core.app.ActivityScenario
 import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.action.ViewActions.click
 import androidx.test.espresso.assertion.ViewAssertions.matches
 import androidx.test.espresso.matcher.ViewMatchers.withId
 import androidx.test.espresso.matcher.ViewMatchers.withText
 import androidx.test.ext.junit.runners.AndroidJUnit4
-import androidx.test.rule.ActivityTestRule
 import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
 import dagger.BindsInstance
 import dagger.Component
 import dagger.Module
 import dagger.Provides
 import kotlinx.coroutines.CoroutineDispatcher
-import org.junit.Rule
+import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.oppia.app.R
@@ -29,8 +29,12 @@ import javax.inject.Singleton
 @RunWith(AndroidJUnit4::class)
 class ConceptCardFragmentTest {
 
-  @get:Rule
-  val activityTestRule = ActivityTestRule(ConceptCardFragmentTestActivity::class.java)
+  private lateinit var activityScenario: ActivityScenario<ConceptCardFragmentTestActivity>
+
+  @Before
+  fun setUp() {
+    activityScenario = ActivityScenario.launch(ConceptCardFragmentTestActivity::class.java)
+  }
 
   @Test
   fun testConceptCardFragment_openDialogFragmentWithSkill1_explanationIsDisplayed() {
@@ -60,7 +64,10 @@ class ConceptCardFragmentTest {
   @Test
   fun testConceptCardFragment_openDialogFragmentWithSkill2_afterConfigurationChange_workedExamplesAreDisplayed() {
     onView(withId(R.id.open_dialog_2)).perform(click())
-    activityTestRule.activity.requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE
+    activityScenario.onActivity { activity ->
+      activity.requestedOrientation = Configuration.ORIENTATION_LANDSCAPE
+    }
+    activityScenario.recreate()
     onView(withText("Worked example without rich text.")).check(matches(isDisplayed()))
     onView(withText("Second worked example.")).check(matches(isDisplayed()))
   }

From a14d0b0b12320ee48e62d46bbb6751ac752e4459 Mon Sep 17 00:00:00 2001
From: James Xu <jamesxu@umich.edu>
Date: Fri, 11 Oct 2019 15:24:13 -0700
Subject: [PATCH 14/14] Fixed package name

---
 .../org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
index cebbd40fcf6..33678f58ab7 100644
--- a/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
+++ b/app/src/sharedTest/java/org/oppia/app/topic/conceptcard/ConceptCardFragmentTest.kt
@@ -1,4 +1,4 @@
-package org.oppia.app.player.audio
+package org.oppia.app.topic.conceptcard
 
 import android.app.Application
 import android.content.Context