Issue#67 Extract JUnit5 MainDispatcher

app/src/test/java/org/fnives/test/showcase/di/DITest.kt

@@ -2,7 +2,7 @@ package org.fnives.test.showcase.di
 
 import android.content.Context
 import org.fnives.test.showcase.model.network.BaseUrl
-import org.fnives.test.showcase.testutils.TestMainDispatcher
+import org.fnives.test.showcase.android.testutil.StandardTestMainDispatcher
 import org.fnives.test.showcase.ui.auth.AuthViewModel
 import org.fnives.test.showcase.ui.home.MainViewModel
 import org.fnives.test.showcase.ui.splash.SplashViewModel
@@ -20,7 +20,7 @@ import org.mockito.kotlin.doReturn
 import org.mockito.kotlin.mock
 import org.mockito.kotlin.whenever
 
-@ExtendWith(TestMainDispatcher::class)
+@ExtendWith(StandardTestMainDispatcher::class)
 class DITest : KoinTest {
 
     private val authViewModel by inject<AuthViewModel>()

app/src/test/java/org/fnives/test/showcase/testutils/TestMainDispatcher.kt

@@ -1,39 +0,0 @@
-package org.fnives.test.showcase.testutils
-
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.test.StandardTestDispatcher
-import kotlinx.coroutines.test.TestDispatcher
-import kotlinx.coroutines.test.resetMain
-import kotlinx.coroutines.test.setMain
-import org.fnives.test.showcase.testutils.TestMainDispatcher.Companion.testDispatcher
-import org.junit.jupiter.api.extension.AfterEachCallback
-import org.junit.jupiter.api.extension.BeforeEachCallback
-import org.junit.jupiter.api.extension.ExtensionContext
-
-/**
- * Custom Junit5 Extension which replaces the main dispatcher with a [TestDispatcher]
- *
- * One can access the test dispatcher via [testDispatcher] static getter.
- */
-@OptIn(ExperimentalCoroutinesApi::class)
-class TestMainDispatcher : BeforeEachCallback, AfterEachCallback {
-
-    override fun beforeEach(context: ExtensionContext?) {
-        val testDispatcher = StandardTestDispatcher()
-        privateTestDispatcher = testDispatcher
-        Dispatchers.setMain(testDispatcher)
-    }
-
-    override fun afterEach(context: ExtensionContext?) {
-        Dispatchers.resetMain()
-        privateTestDispatcher = null
-    }
-
-    companion object {
-        private var privateTestDispatcher: TestDispatcher? = null
-        val testDispatcher: TestDispatcher
-            get() = privateTestDispatcher
-                ?: throw IllegalStateException("TestMainDispatcher is in afterEach State")
-    }
-}

app/src/test/java/org/fnives/test/showcase/ui/auth/AuthViewModelTest.kt

@@ -8,7 +8,7 @@ import org.fnives.test.showcase.core.login.LoginUseCase
 import org.fnives.test.showcase.model.auth.LoginCredentials
 import org.fnives.test.showcase.model.auth.LoginStatus
 import org.fnives.test.showcase.model.shared.Answer
-import org.fnives.test.showcase.testutils.TestMainDispatcher
+import org.fnives.test.showcase.android.testutil.StandardTestMainDispatcher
 import org.fnives.test.showcase.ui.shared.Event
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.DisplayName
@@ -27,13 +27,13 @@ import org.mockito.kotlin.whenever
 import java.util.stream.Stream
 
 @Suppress("TestFunctionName")
-@ExtendWith(InstantExecutorExtension::class, TestMainDispatcher::class)
+@ExtendWith(InstantExecutorExtension::class, StandardTestMainDispatcher::class)
 @OptIn(ExperimentalCoroutinesApi::class)
 internal class AuthViewModelTest {
 
     private lateinit var sut: AuthViewModel
     private lateinit var mockLoginUseCase: LoginUseCase
-    private val testScheduler get() = TestMainDispatcher.testDispatcher.scheduler
+    private val testScheduler get() = StandardTestMainDispatcher.testDispatcher.scheduler
 
     @BeforeEach
     fun setUp() {

app/src/test/java/org/fnives/test/showcase/ui/auth/CodeKataAuthViewModel.kt

@@ -3,20 +3,20 @@ package org.fnives.test.showcase.ui.auth
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import org.fnives.test.showcase.android.testutil.InstantExecutorExtension
 import org.fnives.test.showcase.core.login.LoginUseCase
-import org.fnives.test.showcase.testutils.TestMainDispatcher
+import org.fnives.test.showcase.android.testutil.StandardTestMainDispatcher
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.DisplayName
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.extension.ExtendWith
 import org.mockito.kotlin.mock
 
-@ExtendWith(InstantExecutorExtension::class, TestMainDispatcher::class)
+@ExtendWith(InstantExecutorExtension::class, StandardTestMainDispatcher::class)
 @OptIn(ExperimentalCoroutinesApi::class)
 class CodeKataAuthViewModel {
 
     private lateinit var sut: AuthViewModel
     private lateinit var mockLoginUseCase: LoginUseCase
-    private val testScheduler get() = TestMainDispatcher.testDispatcher.scheduler
+    private val testScheduler get() = StandardTestMainDispatcher.testDispatcher.scheduler
 
     @BeforeEach
     fun setUp() {

app/src/test/java/org/fnives/test/showcase/ui/home/MainViewModelTest.kt

@@ -15,7 +15,7 @@ import org.fnives.test.showcase.model.content.ContentId
 import org.fnives.test.showcase.model.content.FavouriteContent
 import org.fnives.test.showcase.model.content.ImageUrl
 import org.fnives.test.showcase.model.shared.Resource
-import org.fnives.test.showcase.testutils.TestMainDispatcher
+import org.fnives.test.showcase.android.testutil.StandardTestMainDispatcher
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.DisplayName
 import org.junit.jupiter.api.Test
@@ -29,7 +29,7 @@ import org.mockito.kotlin.verifyNoMoreInteractions
 import org.mockito.kotlin.whenever
 
 @Suppress("TestFunctionName")
-@ExtendWith(InstantExecutorExtension::class, TestMainDispatcher::class)
+@ExtendWith(InstantExecutorExtension::class, StandardTestMainDispatcher::class)
 @OptIn(ExperimentalCoroutinesApi::class)
 internal class MainViewModelTest {
 
@@ -39,7 +39,7 @@ internal class MainViewModelTest {
     private lateinit var mockFetchContentUseCase: FetchContentUseCase
     private lateinit var mockAddContentToFavouriteUseCase: AddContentToFavouriteUseCase
     private lateinit var mockRemoveContentFromFavouritesUseCase: RemoveContentFromFavouritesUseCase
-    private val testScheduler get() = TestMainDispatcher.testDispatcher.scheduler
+    private val testScheduler get() = StandardTestMainDispatcher.testDispatcher.scheduler
 
     @BeforeEach
     fun setUp() {

app/src/test/java/org/fnives/test/showcase/ui/splash/SplashViewModelTest.kt

@@ -4,7 +4,7 @@ import com.jraska.livedata.test
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import org.fnives.test.showcase.android.testutil.InstantExecutorExtension
 import org.fnives.test.showcase.core.login.IsUserLoggedInUseCase
-import org.fnives.test.showcase.testutils.TestMainDispatcher
+import org.fnives.test.showcase.android.testutil.StandardTestMainDispatcher
 import org.fnives.test.showcase.ui.shared.Event
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.DisplayName
@@ -14,13 +14,13 @@ import org.mockito.kotlin.doReturn
 import org.mockito.kotlin.mock
 import org.mockito.kotlin.whenever
 
-@ExtendWith(InstantExecutorExtension::class, TestMainDispatcher::class)
+@ExtendWith(InstantExecutorExtension::class, StandardTestMainDispatcher::class)
 @OptIn(ExperimentalCoroutinesApi::class)
 internal class SplashViewModelTest {
 
     private lateinit var mockIsUserLoggedInUseCase: IsUserLoggedInUseCase
     private lateinit var sut: SplashViewModel
-    private val testScheduler get() = TestMainDispatcher.testDispatcher.scheduler
+    private val testScheduler get() = StandardTestMainDispatcher.testDispatcher.scheduler
 
     @BeforeEach
     fun setUp() {

codekata/viewmodel.instructionset.md

@@ -25,12 +25,12 @@ Our test class is `org.fnives.test.showcase.ui.splash.CodeKataSplashViewModelTes
 
 To properly test LiveData we need to make them instant, meaning as soon as the value is set the observers are updated. To Do this we can use a `InstantExecutorExtension`.
 
-Also We need to set MainDispatcher as TestDispatcher, for this we can use the `TestMainDispatcher` Extension.
+Also We need to set MainDispatcher as TestDispatcher, for this we can use the `StandardTestMainDispatcher` Extension.
 
 To add this to our TestClass we need to do the following:
 
 ```kotlin
-@ExtendWith(InstantExecutorExtension::class, TestMainDispatcher::class)
+@ExtendWith(InstantExecutorExtension::class, StandardTestMainDispatcher::class)
 class CodeKataSplashViewModelTest {
 ```
 
@@ -41,7 +41,7 @@ Next let's set up our System Under Test as usual:
 ```kotlin
 private lateinit var mockIsUserLoggedInUseCase: IsUserLoggedInUseCase
 private lateinit var sut: SplashViewModel
-private val testScheduler get() = TestMainDispatcher.testDispatcher.scheduler // just a shortcut
+private val testScheduler get() = StandardTestMainDispatcher.testDispatcher.scheduler // just a shortcut
 
 @BeforeEach
 fun setUp() {
@@ -69,7 +69,7 @@ val navigateToTestObserver = sut.navigateTo.test()
 
 Since the action takes place in the ViewModel constructor, instead of additional calls, we need to simulate that time has elapsed.
 
-Note: the `TestMainDispatcher` Extension we are using sets `StandardTestDispatcher` as the dispatcher for `Dispatcher.Main`, that's why our test is linear and not shaky.
+Note: the `StandardTestMainDispatcher` Extension we are using sets `StandardTestDispatcher` as the dispatcher for `Dispatcher.Main`, that's why our test is linear and not shaky.
 
 ```kotlin
 testScheduler.advanceTimeBy(501)

test-util-junit5-android/build.gradle

@@ -32,4 +32,6 @@ android {
 dependencies {
     implementation "org.junit.jupiter:junit-jupiter-engine:$junit5_version"
     implementation "androidx.arch.core:core-runtime:$arch_core_version"
+
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-test:$coroutines_version"
 }

test-util-junit5-android/src/main/java/org/fnives/test/showcase/android/testutil/StandardTestMainDispatcher.kt

@@ -0,0 +1,30 @@
+package org.fnives.test.showcase.android.testutil
+
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.TestDispatcher
+import org.fnives.test.showcase.android.testutil.StandardTestMainDispatcher.Companion.testDispatcher
+
+/**
+ * Custom Junit5 Extension which replaces the main dispatcher with a Standard [TestDispatcher]
+ *
+ * One can access the test dispatcher via [testDispatcher] static getter.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+class StandardTestMainDispatcher : TestMainDispatcher() {
+
+    override var createdTestDispatcher: TestDispatcher?
+        get() = privateTestDispatcher
+        set(value) {
+            privateTestDispatcher = value
+        }
+
+    override fun createDispatcher(): TestDispatcher = StandardTestDispatcher()
+
+    companion object {
+        private var privateTestDispatcher: TestDispatcher? = null
+        val testDispatcher: TestDispatcher
+            get() = privateTestDispatcher
+                ?: throw IllegalStateException("StandardTestMainDispatcher is in afterEach State")
+    }
+}

test-util-junit5-android/src/main/java/org/fnives/test/showcase/android/testutil/TestMainDispatcher.kt

@@ -0,0 +1,32 @@
+package org.fnives.test.showcase.android.testutil
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.TestDispatcher
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.setMain
+import org.junit.jupiter.api.extension.AfterEachCallback
+import org.junit.jupiter.api.extension.BeforeEachCallback
+import org.junit.jupiter.api.extension.ExtensionContext
+
+/**
+ * Custom Junit5 Extension which replaces the main dispatcher with a [TestDispatcher]
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+abstract class TestMainDispatcher : BeforeEachCallback, AfterEachCallback {
+
+    protected abstract var createdTestDispatcher: TestDispatcher?
+
+    abstract fun createDispatcher() : TestDispatcher
+
+    final override fun beforeEach(context: ExtensionContext?) {
+        val testDispatcher = createDispatcher()
+        createdTestDispatcher = testDispatcher
+        Dispatchers.setMain(testDispatcher)
+    }
+
+    final override fun afterEach(context: ExtensionContext?) {
+        Dispatchers.resetMain()
+        createdTestDispatcher = null
+    }
+}

test-util-junit5-android/src/main/java/org/fnives/test/showcase/android/testutil/UnconfinedTestMainDispatcher.kt

@@ -0,0 +1,30 @@
+package org.fnives.test.showcase.android.testutil
+
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.TestDispatcher
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import org.fnives.test.showcase.android.testutil.UnconfinedTestMainDispatcher.Companion.testDispatcher
+
+/**
+ * Custom Junit5 Extension which replaces the main dispatcher with a Unconfined [TestDispatcher]
+ *
+ * One can access the test dispatcher via [testDispatcher] static getter.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+class UnconfinedTestMainDispatcher : TestMainDispatcher() {
+
+    override var createdTestDispatcher: TestDispatcher?
+        get() = privateTestDispatcher
+        set(value) {
+            privateTestDispatcher = value
+        }
+
+    override fun createDispatcher(): TestDispatcher = UnconfinedTestDispatcher()
+
+    companion object {
+        private var privateTestDispatcher: TestDispatcher? = null
+        val testDispatcher: TestDispatcher
+            get() = privateTestDispatcher
+                ?: throw IllegalStateException("StandardTestMainDispatcher is in afterEach State")
+    }
+}