Add coroutines tests

Author: SmartToolFactory

Tutorial4-2Kotlin-MockK/src/main/java/com/smarttoolfactory/tutorial4_2kotlin_mockk/viewmodel/CalculationUseCase.kt

@@ -1,16 +1,28 @@
 package com.smarttoolfactory.tutorial4_2kotlin_mockk
 
 import com.google.common.truth.Truth
-import kotlinx.coroutines.GlobalScope
-import kotlinx.coroutines.async
-import kotlinx.coroutines.delay
-import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.*
+import kotlinx.coroutines.test.TestCoroutineDispatcher
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.runBlockingTest
+import kotlinx.coroutines.test.setMain
+import org.junit.After
+import org.junit.Before
 import org.junit.jupiter.api.Test
 
+@ExperimentalCoroutinesApi
 class Test16Coroutines {
 
+ private val testCoroutineDispatcher = TestCoroutineDispatcher()
+
+
+ /**
+ * This test passes but it has to WAIT the delay of suspending function
+ */
  @Test
- fun `First Coroutine test`()= runBlocking {
+ fun `First Coroutine test`() = runBlocking {
+
+ println("Test started")
 
  // GIVEN
  val expected = "Hello World"
@@ -22,15 +34,108 @@ class Test16Coroutines {
 
  // THEN
  Truth.assertThat(actual.await()).isEqualTo(expected)
+ println("Test finished")
+
+ }
+
+
+ /**
+ This test FAILS because it's not [TestCoroutineDispatcher]
+ that calling [TestCoroutineDispatcher.runBlockingTest]
+ */
+ @Test
+ fun `Coroutine test with runBlockingTest that fails`() = runBlockingTest {
+
+ println("Test started")
+
+ println("Test thread: ${Thread.currentThread().name}, scope: $this")
+
+ // GIVEN
+ val expected = "Hello World"
+
+ // WHEN
+ val actual = withContext(testCoroutineDispatcher) {
+ println("Test Dispatcher thread: ${Thread.currentThread().name}, scope: $this")
+
+ async {
+ println("Inside async thread: ${Thread.currentThread().name}, scope: $this")
+
+ mockSomeDelayedWork()
+ }
+ }
+
+ // THEN
+ Truth.assertThat(actual.await()).isEqualTo(expected)
+ println("Test finished")
+
+ /*
+ Prints:
+ Test started
+ Test thread: main @coroutine#1, scope: kotlinx.coroutines.test.TestCoroutineScopeImpl@157632c9
+ Test Dispatcher thread: main @coroutine#1, scope: "coroutine#1":DispatchedCoroutine{Active}@67e2d983
+ Inside async thread: main @coroutine#2, scope: "coroutine#2":DeferredCoroutine{Active}@5d47c63f
+ */
+
+ }
+
+ @Test
+ fun `Coroutine test with TestCoroutineDispatcher`() = testCoroutineDispatcher.runBlockingTest {
+
+ println("Test started")
+
+ println("Test thread: ${Thread.currentThread().name}, scope: $this")
+
+ // GIVEN
+ val expected = "Hello World"
+
+ // WHEN
+ val actual = withContext(testCoroutineDispatcher) {
+ println("Test Dispatcher thread: ${Thread.currentThread().name}, scope: $this")
+
+ async {
+ println("Inside async thread: ${Thread.currentThread().name}, scope: $this")
+
+ mockSomeDelayedWork()
+ }
+ }
+
+ // THEN
+ Truth.assertThat(actual.await()).isEqualTo(expected)
+ println("Test finished")
+
+ /*
+ Prints:
+
+ Test started
+ Test thread: main @coroutine#1, scope: kotlinx.coroutines.test.TestCoroutineScopeImpl@157632c9
+ Test Dispatcher thread: main @coroutine#1, scope: "coroutine#1":UndispatchedCoroutine{Active}@3bbc39f8
+ Inside async thread: main @coroutine#2, scope: "coroutine#2":DeferredCoroutine{Active}@4ae3c1cd
+ Test finished
+ */
+
+ }
+
+ @Before
+ fun setUp() {
+ Dispatchers.setMain(testCoroutineDispatcher)
  }
 
+ @After
+ fun tearDown() {
+ Dispatchers.resetMain()
+ try {
+ testCoroutineDispatcher.cleanupTestCoroutines()
+ } catch (e: Exception) {
+ e.printStackTrace()
+ }
+ }
 
 }
 
 
 private suspend fun mockSomeDelayedWork(): String {
 
- delay(10_000)
+ delay(5_000)
  return "Hello World"
 
 }

Tutorial4-2Kotlin-MockK/src/main/java/com/smarttoolfactory/tutorial4_2kotlin_mockk/viewmodel/CalculationViewModel.kt

@@ -17,12 +17,18 @@ class TestCoroutineRule : TestRule {
  override fun apply(base: Statement, description: Description?) = object : Statement() {
  @Throws(Throwable::class)
  override fun evaluate() {
+
  Dispatchers.setMain(testCoroutineDispatcher)
 
  base.evaluate()
 
  Dispatchers.resetMain()
- testCoroutineScope.cleanupTestCoroutines()
+
+ try {
+ testCoroutineScope.cleanupTestCoroutines()
+ } catch (e: Exception) {
+ e.printStackTrace()
+ }
  }
  }