BAEL-2769 Added MockK examples

kotlin-libraries/pom.xml

@@ -140,6 +140,32 @@
             <artifactId>kotlinx-collections-immutable</artifactId>
             <version>0.1</version>
         </dependency>
+
+        <!-- MockK dependencies-->
+        <dependency>
+            <groupId>io.mockk</groupId>
+            <artifactId>mockk</artifactId>
+            <version>${mockk.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>net.bytebuddy</groupId>
+            <artifactId>byte-buddy</artifactId>
+            <version>1.8.13</version>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>net.bytebuddy</groupId>
+            <artifactId>byte-buddy-agent</artifactId>
+            <version>1.8.13</version>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.objenesis</groupId>
+            <artifactId>objenesis</artifactId>
+            <version>2.6</version>
+            <scope>compile</scope>
+        </dependency>
     </dependencies>
 
     <properties>
@@ -154,6 +180,7 @@
         <assertj.version>3.10.0</assertj.version>
         <h2database.version>1.4.197</h2database.version>
         <exposed.version>0.10.4</exposed.version>
+        <mockk.version>1.9.3</mockk.version>
     </properties>
 
 </project>

kotlin-libraries/src/test/kotlin/com/baeldung/mockk/AnnotationMockKUnitTest.kt

@@ -0,0 +1,44 @@
+package com.baeldung.mockk
+
+import io.mockk.MockKAnnotations
+import io.mockk.every
+import io.mockk.impl.annotations.InjectMockKs
+import io.mockk.impl.annotations.MockK
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import kotlin.test.assertEquals
+
+class InjectTestService {
+    lateinit var service1: TestableService
+    lateinit var service2: TestableService
+
+    fun invokeService1(): String {
+        return service1.getDataFromDb("Test Param")
+    }
+}
+
+class AnnotationMockKUnitTest {
+
+    @MockK
+    lateinit var service1: TestableService
+
+    @MockK
+    lateinit var service2: TestableService
+
+    @InjectMockKs
+    var objectUnderTest = InjectTestService()
+
+    @BeforeEach
+    fun setUp() = MockKAnnotations.init(this)
+
+    @Test
+    fun givenServiceMock_whenCallingMockedMethod_thenCorrectlyVerified() {
+        // given
+        every { service1.getDataFromDb("Test Param") } returns "No"
+        // when
+        val result = objectUnderTest.invokeService1()
+        // then
+        assertEquals("No", result)
+    }
+
+}

kotlin-libraries/src/test/kotlin/com/baeldung/mockk/BasicMockKUnitTest.kt

@@ -0,0 +1,92 @@
+package com.baeldung.mockk
+
+import io.mockk.*
+import org.junit.jupiter.api.Test
+import kotlin.test.assertEquals
+
+
+class BasicMockKUnitTest {
+
+    @Test
+    fun givenServiceMock_whenCallingMockedMethod_thenCorrectlyVerified() {
+        // given
+        val service = mockk<TestableService>()
+        every { service.getDataFromDb("Expected Param") } returns "Expected Output"
+        // when
+        val result = service.getDataFromDb("Expected Param")
+        // then
+        verify { service.getDataFromDb("Expected Param") }
+        assertEquals("Expected Output", result)
+    }
+
+    @Test
+    fun givenServiceSpy_whenMockingOnlyOneMethod_thenOtherMethodsShouldBehaveAsOriginalObject() {
+        // given
+        val service = spyk<TestableService>()
+        every { service.getDataFromDb(any()) } returns "Mocked Output"
+        // when checking mocked method
+        val firstResult = service.getDataFromDb("Any Param")
+        // then
+        assertEquals("Mocked Output", firstResult)
+        // when checking not mocked method
+        val secondResult = service.doSomethingElse("Any Param")
+        // then
+        assertEquals("I don't want to!", secondResult)
+    }
+
+    @Test
+    fun givenRelaxedMock_whenCallingNotMockedMethod_thenReturnDefaultValue() {
+        // given
+        val service = mockk<TestableService>(relaxed = true)
+        // when
+        val result = service.getDataFromDb("Any Param")
+        // then
+        assertEquals("", result)
+    }
+
+    @Test
+    fun givenObject_whenMockingIt_thenMockedMethodShouldReturnProperValue() {
+        // given
+        val service = TestableService()
+        mockkObject(service)
+        // when calling not mocked method
+        val firstResult = service.getDataFromDb("Any Param")
+        // then return real response
+        assertEquals("Value from DB", firstResult)
+
+        // when calling mocked method
+        every { service.getDataFromDb(any()) } returns "Mocked Output"
+        val secondResult = service.getDataFromDb("Any Param")
+        // then return mocked response
+        assertEquals("Mocked Output", secondResult)
+    }
+
+    @Test
+    fun givenMock_whenCapturingParamValue_thenProperValueShouldBeCaptured() {
+        // given
+        val service = mockk<TestableService>()
+        val slot = slot<String>()
+        every { service.getDataFromDb(capture(slot)) } returns "Expected Output"
+        // when
+        service.getDataFromDb("Expected Param")
+        // then
+        assertEquals("Expected Param", slot.captured)
+    }
+
+    @Test
+    fun givenMock_whenCapturingParamsValues_thenProperValuesShouldBeCaptured() {
+        // given
+        val service = mockk<TestableService>()
+        val list = mutableListOf<String>()
+        every { service.getDataFromDb(capture(list)) } returns "Expected Output"
+        // when
+        service.getDataFromDb("Expected Param 1")
+        service.getDataFromDb("Expected Param 2")
+        // then
+        assertEquals(2, list.size)
+        assertEquals("Expected Param 1", list[0])
+        assertEquals("Expected Param 2", list[1])
+    }
+
+
+}

kotlin-libraries/src/test/kotlin/com/baeldung/mockk/HierarchicalMockKUnitTest.kt

@@ -0,0 +1,33 @@
+package com.baeldung.mockk
+
+import io.mockk.*
+import org.junit.jupiter.api.Test
+import kotlin.test.assertEquals
+
+class Foo {
+    lateinit var name: String
+    lateinit var bar: Bar
+}
+
+class Bar {
+    lateinit var nickname: String
+}
+
+class HierarchicalMockKUnitTest {
+
+    @Test
+    fun givenHierarchicalClass_whenMockingIt_thenReturnProperValue() {
+        // given
+        val foo = mockk<Foo> {
+            every { name } returns "Karol"
+            every { bar } returns mockk {
+                every { nickname } returns "Tomato"
+            }
+        }
+        // when
+        val result = foo.bar.nickname
+        // then
+        assertEquals("Tomato", result)
+    }
+
+}

kotlin-libraries/src/test/kotlin/com/baeldung/mockk/TestableService.kt

@@ -0,0 +1,12 @@
+package com.baeldung.mockk
+
+class TestableService {
+    fun getDataFromDb(testParameter: String): String {
+        // query database and return matching value
+        return "Value from DB"
+    }
+
+    fun doSomethingElse(testParameter: String): String  {
+        return "I don't want to!"
+    }
+}