Add Hilt(Dagger) example of robolectric tests in app

app/src/robolectricTestHilt/java/org/fnives/test/showcase/favourite/FavouriteContentLocalStorageImplTest.kt

@@ -0,0 +1,97 @@
+package org.fnives.test.showcase.favourite
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import dagger.hilt.android.testing.HiltAndroidRule
+import dagger.hilt.android.testing.HiltAndroidTest
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.async
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.take
+import kotlinx.coroutines.flow.toList
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.test.TestCoroutineDispatcher
+import org.fnives.test.showcase.core.storage.content.FavouriteContentLocalStorage
+import org.fnives.test.showcase.model.content.ContentId
+import org.fnives.test.showcase.storage.database.DatabaseInitialization
+import org.junit.Assert
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import javax.inject.Inject
+
+@Suppress("TestFunctionName")
+@OptIn(ExperimentalCoroutinesApi::class)
+@RunWith(AndroidJUnit4::class)
+@HiltAndroidTest
+internal class FavouriteContentLocalStorageImplTest {
+
+    @get:Rule
+    val hiltRule = HiltAndroidRule(this)
+
+    @Inject
+    lateinit var sut : FavouriteContentLocalStorage
+    private lateinit var testDispatcher: TestCoroutineDispatcher
+
+    @Before
+    fun setUp() {
+        testDispatcher = TestCoroutineDispatcher()
+        DatabaseInitialization.dispatcher = testDispatcher
+        hiltRule.inject()
+    }
+
+    @Test
+    fun GIVEN_content_id_WHEN_added_to_Favourite_THEN_it_can_be_read_out() = runBlocking {
+        val expected = listOf(ContentId("a"))
+
+        sut.markAsFavourite(ContentId("a"))
+        val actual = sut.observeFavourites().first()
+
+        Assert.assertEquals(expected, actual)
+    }
+
+    @Test
+    fun GIVEN_content_id_added_WHEN_removed_to_Favourite_THEN_it_no_longer_can_be_read_out() =
+        runBlocking {
+            val expected = listOf<ContentId>()
+            sut.markAsFavourite(ContentId("b"))
+
+            sut.deleteAsFavourite(ContentId("b"))
+            val actual = sut.observeFavourites().first()
+
+            Assert.assertEquals(expected, actual)
+        }
+
+    @Test
+    fun GIVEN_empty_database_WHILE_observing_content_WHEN_favourite_added_THEN_change_is_emitted() =
+        runBlocking<Unit> {
+            val expected = listOf(listOf(), listOf(ContentId("a")))
+
+            val testDispatcher = TestCoroutineDispatcher()
+            val actual = async(testDispatcher) {
+                sut.observeFavourites().take(2).toList()
+            }
+            testDispatcher.advanceUntilIdle()
+
+            sut.markAsFavourite(ContentId("a"))
+
+            Assert.assertEquals(expected, actual.await())
+        }
+
+    @Test
+    fun GIVEN_non_empty_database_WHILE_observing_content_WHEN_favourite_removed_THEN_change_is_emitted() =
+        runBlocking<Unit> {
+            val expected = listOf(listOf(ContentId("a")), listOf())
+            sut.markAsFavourite(ContentId("a"))
+
+            val testDispatcher = TestCoroutineDispatcher()
+            val actual = async(testDispatcher) {
+                sut.observeFavourites().take(2).toList()
+            }
+            testDispatcher.advanceUntilIdle()
+
+            sut.deleteAsFavourite(ContentId("a"))
+
+            Assert.assertEquals(expected, actual.await())
+        }
+}

app/src/robolectricTestHilt/resources/org/fnives/test/showcase/favourite/robolectric.properties

@@ -0,0 +1,4 @@
+sdk=28
+shadows=org.fnives.test.showcase.testutils.shadow.ShadowSnackbar
+instrumentedPackages=androidx.loader.content
+application=dagger.hilt.android.testing.HiltTestApplication