[UPDATE/OPTIMIZE] Add tests for PlantDetailViewModel and adjust add()

app/src/androidTest/java/com/google/samples/apps/sunflower/viewmodels/PlantDetailViewModelTest.kt

@@ -17,23 +17,35 @@
 package com.google.samples.apps.sunflower.viewmodels
 
 import androidx.arch.core.executor.testing.InstantTaskExecutorRule
+import androidx.lifecycle.viewModelScope
 import androidx.room.Room
 import androidx.test.InstrumentationRegistry
 import com.google.samples.apps.sunflower.data.AppDatabase
 import com.google.samples.apps.sunflower.data.GardenPlantingRepository
 import com.google.samples.apps.sunflower.data.PlantRepository
 import com.google.samples.apps.sunflower.utilities.getValue
 import com.google.samples.apps.sunflower.utilities.testPlant
+import com.google.samples.apps.sunflower.utilities.testPlants
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.runBlocking
 import org.junit.After
 import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertNull
 import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
+import java.util.concurrent.TimeUnit
 
 class PlantDetailViewModelTest {
 
     private lateinit var appDatabase: AppDatabase
     private lateinit var viewModel: PlantDetailViewModel
+    private lateinit var plantRepo: PlantRepository
+    private lateinit var gardenPlantingRepo: GardenPlantingRepository
 
     @get:Rule
     var instantTaskExecutorRule = InstantTaskExecutorRule()
@@ -43,9 +55,9 @@ class PlantDetailViewModelTest {
         val context = InstrumentationRegistry.getTargetContext()
         appDatabase = Room.inMemoryDatabaseBuilder(context, AppDatabase::class.java).build()
 
-        val plantRepo = PlantRepository.getInstance(appDatabase.plantDao())
-        val gardenPlantingRepo = GardenPlantingRepository.getInstance(
-                appDatabase.gardenPlantingDao())
+        plantRepo = PlantRepository.getInstance(appDatabase.plantDao())
+        gardenPlantingRepo = GardenPlantingRepository.getInstance(appDatabase.gardenPlantingDao())
+        appDatabase.plantDao().insertAll(testPlants)
         viewModel = PlantDetailViewModel(plantRepo, gardenPlantingRepo, testPlant.plantId)
     }
 
@@ -59,4 +71,59 @@ class PlantDetailViewModelTest {
     fun testDefaultValues() {
         assertFalse(getValue(viewModel.isPlanted))
     }
+
+    @Test
+    fun shouldAddPlantToGarden() = runBlocking {
+        val plantToAdd = testPlants[1]
+        viewModel = PlantDetailViewModel(plantRepo, gardenPlantingRepo, plantToAdd.plantId)
+
+        launch {
+            viewModel.addPlantToGarden()
+            // DB needs time to update itself.
+            delay(TimeUnit.SECONDS.toMillis(1))
+        }.join()
+
+        val plantAdded =
+            getValue(gardenPlantingRepo.getGardenPlantingForPlant(plantToAdd.plantId))
+        assertNotNull(plantAdded)
+    }
+
+    @Test
+    fun shouldCancelAddingPlantToGarden() = runBlocking {
+        val plantToAdd = testPlants[2]
+        viewModel = PlantDetailViewModel(plantRepo, gardenPlantingRepo, plantToAdd.plantId)
+
+        launch {
+            viewModel.addPlantToGarden().cancel()
+
+            // Manually wait 1 sec, the adding should not happen due to call the cancel().
+            delay(TimeUnit.SECONDS.toMillis(1))
+        }.join()
+
+        val plantJustAdded =
+            getValue(gardenPlantingRepo.getGardenPlantingForPlant(plantToAdd.plantId))
+        assertNull(plantJustAdded)
+    }
+
+    @ExperimentalCoroutinesApi
+    @Test
+    fun shouldCancelAddingPlantToGardenByViewModel() = runBlocking {
+        val plantToAdd = testPlants[2]
+        viewModel = PlantDetailViewModel(plantRepo, gardenPlantingRepo, plantToAdd.plantId)
+
+        launch {
+            viewModel.addPlantToGarden()
+        }
+
+        launch {
+            viewModel.viewModelScope.cancel()
+
+            // Manually wait 1 sec, the adding should not happen due to call the cancel().
+            delay(TimeUnit.SECONDS.toMillis(1))
+        }.join()
+
+        val plantJustAdded =
+            getValue(gardenPlantingRepo.getGardenPlantingForPlant(plantToAdd.plantId))
+        assertNull(plantJustAdded)
+    }
 }

app/src/main/java/com/google/samples/apps/sunflower/viewmodels/PlantDetailViewModel.kt

@@ -25,6 +25,7 @@ import com.google.samples.apps.sunflower.data.GardenPlantingRepository
 import com.google.samples.apps.sunflower.data.Plant
 import com.google.samples.apps.sunflower.data.PlantRepository
 import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.cancel
 import kotlinx.coroutines.launch
 
@@ -61,8 +62,8 @@ class PlantDetailViewModel(
         plant = plantRepository.getPlant(plantId)
     }
 
-    fun addPlantToGarden() {
-        viewModelScope.launch {
+    fun addPlantToGarden(): Job {
+        return viewModelScope.launch {
             gardenPlantingRepository.createGardenPlanting(plantId)
         }
     }