Implemented Instrumentation test for NotificationDatastore.kt

NotificationDatastoreTest tests all the possible edge cases which might cause problem in working of new notification system.

AnkiDroid/src/androidTest/java/com/ichi2/anki/NotificationDatastoreTest.kt

@@ -0,0 +1,88 @@
+package com.ichi2.anki
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.platform.app.InstrumentationRegistry
+import com.ichi2.anki.model.DeckNotification
+import kotlinx.coroutines.runBlocking
+import org.intellij.lang.annotations.Language
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import kotlin.random.Random
+import kotlin.test.assertNotNull
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
+
+@RunWith(AndroidJUnit4::class)
+class NotificationDatastoreTest {
+    private lateinit var notificationDatastore: NotificationDatastore
+
+    @Before
+    fun setup() {
+        val context = InstrumentationRegistry.getInstrumentation().targetContext
+        notificationDatastore = NotificationDatastore.getInstance(context)
+    }
+
+    @Test
+    fun deckSchedDataReadWriteTest() {
+        val deckNotification = DeckNotification()
+
+        runBlocking {
+            val isSuccess = notificationDatastore.setDeckSchedData(
+                deckNotification.did,
+                deckNotification
+            )
+            assertTrue(
+                isSuccess,
+                "Unable to save the deck data in notification preference datastore."
+            )
+
+            val dataStored = notificationDatastore.getDeckSchedData(deckNotification.did)
+            assertNotNull(
+                dataStored,
+                "Unable to read the stored deck data from notification preference datastore."
+            )
+        }
+    }
+
+    @Test
+    fun unStoredDeckSchedDataTest() {
+        runBlocking {
+            val deckIdUnStored = Random.nextLong()
+            val dataUnStored = notificationDatastore.getDeckSchedData(deckIdUnStored)
+            assertNull(dataUnStored, "Expected null, But found data for deckId $deckIdUnStored")
+        }
+    }
+
+    @Test(expected = Exception::class)
+    fun deckSchedDataDeSerializationTest() {
+        val deckId = 2L
+
+        @Language("JSON")
+        val invalidDeckSchedJson = """
+            {
+               "deckPreference":{
+                  "number":10,
+                  "valueType":"CARDS"
+               },
+               "did":1,
+               "enabled":false,
+               "includeSubdecks":true,
+               "notificationTime": 0
+            }
+        """.trimIndent()
+
+        runBlocking {
+            notificationDatastore.putStringAsync(deckId.toString(), invalidDeckSchedJson)
+            notificationDatastore.getDeckSchedData(deckId)
+        }
+    }
+
+    @After
+    fun cleanUp() {
+        runBlocking {
+            notificationDatastore.clearDatastore()
+        }
+    }
+}

AnkiDroid/src/main/java/com/ichi2/anki/NotificationDatastore.kt

@@ -213,11 +213,6 @@ class NotificationDatastore private constructor(val context: Context) {
      * */
     /*
     * We actually are not blocking the thread. This method throws an exception. It will not create problem for us.
-    * TODO: unit test that :
-    *  * if there is no preference at all, we return null
-    *  * if there is a preference without entry for this key we return null
-    *  * if there is a preference whose entry for this key can't be cast to DeckNotification, throw
-    *  * if there is a preference with entry for this key that can be cast, we get expected notification
     */
     @Suppress("BlockingMethodInNonBlockingContext")
     suspend fun getDeckSchedData(did: DeckId): DeckNotification? {