Fix #138: Topic train fragment Low-fi UI (Part 4)

app/src/main/java/org/oppia/app/topic/questionplayer/QuestionPlayerActivity.kt

@@ -27,5 +27,9 @@ class QuestionPlayerActivity : InjectableAppCompatActivity() {
       intent.putExtra(QUESTION_PLAYER_ACTIVITY_SKILL_ID_LIST_ARGUMENT_KEY, skillIdList)
       return intent
     }
+
+    fun getIntentKey():String{
+      return QUESTION_PLAYER_ACTIVITY_SKILL_ID_LIST_ARGUMENT_KEY
+    }
   }
 }

app/src/sharedTest/java/org/oppia/app/RecyclerViewMatcher.kt

@@ -0,0 +1,54 @@
+package org.oppia.app
+
+import android.content.res.Resources
+import android.view.View
+import androidx.recyclerview.widget.RecyclerView
+import org.hamcrest.Description
+import org.hamcrest.Matcher
+import org.hamcrest.TypeSafeMatcher
+
+class RecyclerViewMatcher(private val recyclerViewId: Int) {
+  fun atPosition(position: Int): Matcher<View> {
+    return atPositionOnView(position, -1)
+  }
+
+  fun atPositionOnView(position: Int, targetViewId: Int): Matcher<View> {
+    return object : TypeSafeMatcher<View>() {
+      var resources: Resources? = null
+      var childView: View? = null
+
+      override fun describeTo(description: Description) {
+        var idDescription = Integer.toString(recyclerViewId)
+        if (this.resources != null) {
+          idDescription = try {
+            this.resources!!.getResourceName(recyclerViewId)
+          } catch (var4: Resources.NotFoundException) {
+            String.format(
+              "%s (resource name not found)",
+              recyclerViewId
+            )
+          }
+        }
+        description.appendText("with id: $idDescription")
+      }
+
+      public override fun matchesSafely(view: View): Boolean {
+        this.resources = view.resources
+        if (childView == null) {
+          val recyclerView = view.rootView.findViewById<View>(recyclerViewId) as RecyclerView
+          if (recyclerView.id == recyclerViewId) {
+            childView = recyclerView.findViewHolderForAdapterPosition(position)!!.itemView
+          } else {
+            return false
+          }
+        }
+        return if (targetViewId == -1) {
+          view === childView
+        } else {
+          val targetView = childView!!.findViewById<View>(targetViewId)
+          view === targetView
+        }
+      }
+    }
+  }
+}

app/src/sharedTest/java/org/oppia/app/topic/TopicActivityTest.kt

@@ -16,7 +16,6 @@ import kotlinx.coroutines.CoroutineDispatcher
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.oppia.app.R
-import org.oppia.app.player.exploration.ExplorationActivity
 import org.oppia.util.threading.BackgroundDispatcher
 import org.oppia.util.threading.BlockingDispatcher
 import javax.inject.Singleton
@@ -27,7 +26,7 @@ class TopicActivityTest {
 
   @Test
   fun testTopicActivity_loadTopicFragment_hasDummyString() {
-    ActivityScenario.launch(ExplorationActivity::class.java).use {
+    ActivityScenario.launch(TopicActivity::class.java).use {
       onView(withId(R.id.dummy_text_view)).check(matches(withText("This is dummy TextView for testing")))
     }
   }

app/src/sharedTest/java/org/oppia/app/topic/questionplayer/QuestionPlayerActivityTest.kt

@@ -0,0 +1,65 @@
+package org.oppia.app.topic.questionplayer
+
+import android.app.Application
+import android.content.Context
+import androidx.test.core.app.ActivityScenario
+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 dagger.BindsInstance
+import dagger.Component
+import dagger.Module
+import dagger.Provides
+import kotlinx.coroutines.CoroutineDispatcher
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.oppia.app.R
+import org.oppia.util.threading.BackgroundDispatcher
+import org.oppia.util.threading.BlockingDispatcher
+import javax.inject.Singleton
+
+/** Tests for [QuestionPlayerActivity]. */
+@RunWith(AndroidJUnit4::class)
+class QuestionPlayerActivityTest {
+
+  @Test
+  fun testQuestionPlayerActivity_loadQuestionPlayerFragment_hasDummyString() {
+    ActivityScenario.launch(QuestionPlayerActivity::class.java).use {
+      onView(withId(R.id.dummy_text_view)).check(matches(withText("This is dummy TextView for testing")))
+    }
+  }
+
+  @Module
+  class TestModule {
+    @Provides
+    @Singleton
+    fun provideContext(application: Application): Context {
+      return application
+    }
+
+    // TODO(#89): Introduce a proper IdlingResource for background dispatchers to ensure they all complete before
+    //  proceeding in an Espresso test. This solution should also be interoperative with Robolectric contexts by using a
+    //  test coroutine dispatcher.
+
+    @Singleton
+    @Provides
+    @BackgroundDispatcher
+    fun provideBackgroundDispatcher(@BlockingDispatcher blockingDispatcher: CoroutineDispatcher): CoroutineDispatcher {
+      return blockingDispatcher
+    }
+  }
+
+  @Singleton
+  @Component(modules = [TestModule::class])
+  interface TestApplicationComponent {
+    @Component.Builder
+    interface Builder {
+      @BindsInstance
+      fun setApplication(application: Application): Builder
+
+      fun build(): TestApplicationComponent
+    }
+  }
+}

app/src/sharedTest/java/org/oppia/app/topic/train/TopicTrainFragmentTest.kt

@@ -2,36 +2,133 @@ package org.oppia.app.topic.train
 
 import android.app.Application
 import android.content.Context
+import android.content.pm.ActivityInfo
 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.intent.Intents.intended
+import androidx.test.espresso.matcher.ViewMatchers.hasDescendant
+import androidx.test.espresso.matcher.ViewMatchers.isClickable
 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.intent.matcher.IntentMatchers.hasExtra
+import androidx.test.espresso.intent.matcher.IntentMatchers.hasComponent
 import dagger.BindsInstance
 import dagger.Component
 import dagger.Module
 import dagger.Provides
 import kotlinx.coroutines.CoroutineDispatcher
+import org.hamcrest.Matchers.not
 import org.junit.Test
 import org.junit.runner.RunWith
-import org.oppia.app.R
 import org.oppia.app.topic.TopicActivity
 import org.oppia.util.threading.BackgroundDispatcher
 import org.oppia.util.threading.BlockingDispatcher
 import javax.inject.Singleton
+import androidx.test.espresso.intent.Intents
+import androidx.test.espresso.matcher.ViewMatchers.isChecked
+import org.oppia.app.R
+import org.oppia.app.RecyclerViewMatcher
+import org.junit.After
+import org.junit.Before
+import org.junit.Rule
+import androidx.test.rule.ActivityTestRule
+import org.oppia.app.topic.questionplayer.QuestionPlayerActivity
 
 /** Tests for [TopicTrainFragment]. */
 @RunWith(AndroidJUnit4::class)
 class TopicTrainFragmentTest {
 
+  private var skillIdList = ArrayList<String>()
+
+  @get:Rule
+  var activityTestRule: ActivityTestRule<TopicActivity> = ActivityTestRule(
+    TopicActivity::class.java, /* initialTouchMode= */ true, /* launchActivity= */ false
+  )
+
+  @Before
+  fun setUp() {
+    Intents.init()
+    skillIdList.add("test_skill_id_0")
+    skillIdList.add("test_skill_id_1")
+  }
+
+  @Test
+  fun testTopicTrainFragment_loadFragment_displaySkills_startButtonIsInactive() {
+    ActivityScenario.launch(TopicActivity::class.java).use {
+      onView(withId(R.id.master_skills_text_view)).check(matches(withText(R.string.topic_train_master_these_skills)))
+      onView(withRecyclerView(R.id.skill_recycler_view).atPosition(0))
+        .check(matches(hasDescendant(withId(R.id.skill_check_box))))
+      onView(withId(R.id.topic_train_start_button)).check(matches(not(isClickable())))
+    }
+  }
+
   @Test
-  fun testTopicTrainFragment_loadFragment_textIsDisplayed() {
+  fun testTopicTrainFragment_loadFragment_selectSkills_deselectSkills_startButtonIsInactive() {
     ActivityScenario.launch(TopicActivity::class.java).use {
-      onView(withId(R.id.dummy_text_view)).check(matches(withText("This is dummy TextView for testing")))
+      onView(withId(R.id.master_skills_text_view)).check(matches(withText(R.string.topic_train_master_these_skills)))
+      onView(withRecyclerView(R.id.skill_recycler_view).atPosition(0)).perform(click())
+      onView(withId(R.id.topic_train_start_button)).check(matches(isClickable()))
+      onView(withRecyclerView(R.id.skill_recycler_view).atPosition(0)).perform(click())
+      onView(withId(R.id.topic_train_start_button)).check(matches(not(isClickable())))
     }
   }
 
+  @Test
+  fun testTopicTrainFragment_loadFragment_selectSkills_clickStartButton_skillListTransferSuccessfully() {
+    activityTestRule.launchActivity(null)
+    onView(withId(R.id.master_skills_text_view)).check(matches(withText(R.string.topic_train_master_these_skills)))
+    onView(withRecyclerView(R.id.skill_recycler_view).atPosition(0)).perform(click())
+    onView(withRecyclerView(R.id.skill_recycler_view).atPosition(1)).perform(click())
+    onView(withId(R.id.topic_train_start_button)).check(matches(isClickable()))
+    onView(withId(R.id.topic_train_start_button)).perform(click())
+    intended(hasComponent(QuestionPlayerActivity::class.java.name))
+    intended(hasExtra(QuestionPlayerActivity.getIntentKey(), skillIdList))
+  }
+
+  @Test
+  fun testTopicTrainFragment_loadFragment_selectSkills_configurationChange_skillsAreSelected() {
+    activityTestRule.launchActivity(null)
+    onView(withId(R.id.master_skills_text_view)).check(matches(withText(R.string.topic_train_master_these_skills)))
+    onView(withRecyclerView(R.id.skill_recycler_view).atPosition(0)).perform(click())
+    activityTestRule.activity.requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE
+    onView(
+      withRecyclerView(R.id.skill_recycler_view).atPositionOnView(
+        0,
+        R.id.skill_check_box
+      )
+    ).check(matches(isChecked()))
+  }
+
+  @Test
+  fun testTopicTrainFragment_loadFragment_configurationChange_startButtonRemainsInactive() {
+    activityTestRule.launchActivity(null)
+    onView(withId(R.id.topic_train_start_button)).check(matches(not(isClickable())))
+    activityTestRule.activity.requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE
+    onView(withId(R.id.topic_train_start_button)).check(matches(not(isClickable())))
+  }
+
+  @Test
+  fun testTopicTrainFragment_loadFragment_selectSkills_configurationChange_startButtonRemainsActive() {
+    activityTestRule.launchActivity(null)
+    onView(withId(R.id.master_skills_text_view)).check(matches(withText(R.string.topic_train_master_these_skills)))
+    onView(withRecyclerView(R.id.skill_recycler_view).atPosition(0)).perform(click())
+    onView(withId(R.id.topic_train_start_button)).check(matches(isClickable()))
+    activityTestRule.activity.requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE
+    onView(withId(R.id.topic_train_start_button)).check(matches(isClickable()))
+  }
+
+  private fun withRecyclerView(recyclerViewId: Int): RecyclerViewMatcher {
+    return RecyclerViewMatcher(recyclerViewId)
+  }
+
+  @After
+  fun tearDown() {
+    Intents.release()
+  }
+
   @Module
   class TestModule {
     @Provides