Add example of testing classes using mocks of Mockito / JMock libs

Moved from repo: https://github.com/andrei-punko/java-interview-coding

README.md

@@ -23,6 +23,7 @@
   - MapStruct mapper [example](common/src/main/java/by/andd3dfx/mapper)
   - [Example](common/src/main/java/by/andd3dfx/masking) of annotation-driven masker
   - [Example](common/src/main/java/by/andd3dfx/sockets) of work with sockets
+  - [Example](common/src/main/java/by/andd3dfx/testing) of testing classes using Mockito / JMock mocks
 
 
 * **custom-spring-boot-starter**  

common/pom.xml

@@ -60,6 +60,18 @@
             <version>3.25.3</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.jmock</groupId>
+            <artifactId>jmock-legacy</artifactId>
+            <version>2.12.0</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jmock</groupId>
+            <artifactId>jmock-imposters</artifactId>
+            <version>2.12.0</version>
+            <scope>test</scope>
+        </dependency>
 
         <dependency>
             <groupId>org.jasypt</groupId>

common/src/main/java/by/andd3dfx/testing/ClassThatShouldBeTested.java

@@ -0,0 +1,10 @@
+package by.andd3dfx.testing;
+
+public class ClassThatShouldBeTested {
+
+    RealClass realClass;
+
+    public int someMethod(int x, int y) {
+        return realClass.someMethod(x, y);
+    }
+}

common/src/main/java/by/andd3dfx/testing/RealClass.java

@@ -0,0 +1,8 @@
+package by.andd3dfx.testing;
+
+public class RealClass {
+
+    public int someMethod(int x, int y) {
+        return 0;
+    }
+}

common/src/test/java/by/andd3dfx/testing/ClassThatShouldBeTestedUsingJMockTest.java

@@ -0,0 +1,40 @@
+package by.andd3dfx.testing;
+
+import org.jmock.Expectations;
+import org.jmock.Mockery;
+import org.jmock.imposters.ByteBuddyClassImposteriser;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+public class ClassThatShouldBeTestedUsingJMockTest {
+
+    /**
+     * To mock real class, not interface, we need to set imposteriser into mockery
+     */
+    private Mockery mockery = new Mockery() {{
+        setImposteriser(ByteBuddyClassImposteriser.INSTANCE);
+    }};
+    private ClassThatShouldBeTested classThatShouldBeTested;
+
+    @Before
+    public void setup() {
+        classThatShouldBeTested = new ClassThatShouldBeTested();
+        classThatShouldBeTested.realClass = mockery.mock(RealClass.class);
+    }
+
+    @Test
+    public void someMethod() {
+        mockery.checking(new Expectations() {
+            {
+                oneOf(classThatShouldBeTested.realClass).someMethod(2, 5);
+                will(returnValue(3));
+            }
+        });
+        int result = classThatShouldBeTested.someMethod(2, 5);
+
+        assertThat("Wrong result", result, is(3));
+    }
+}

common/src/test/java/by/andd3dfx/testing/ClassThatShouldBeTestedUsingMockitoTest.java

@@ -0,0 +1,29 @@
+package by.andd3dfx.testing;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.mockito.Mockito.when;
+
+@RunWith(MockitoJUnitRunner.class)
+public class ClassThatShouldBeTestedUsingMockitoTest {
+
+    @InjectMocks
+    ClassThatShouldBeTested classThatShouldBeTested;
+    @Mock
+    RealClass realClassMock;
+
+    @Test
+    public void someMethod() {
+        when(realClassMock.someMethod(2, 5)).thenReturn(3);
+
+        int result = classThatShouldBeTested.someMethod(2, 5);
+
+        assertThat("Wrong result", result, is(3));
+    }
+}