MockitoTest.java

package com.art.test;



import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.util.Iterator;

import org.junit.Test;
import org.mockito.Mockito;

import static org.junit.Assert.*;
import static org.mockito.Mockito.*;


public class MockitoTest{
  
  
  @Test
  public void testIterator(){
    
    //Mock Class
    Iterator i = mock(Iterator.class);

    //Arrange (Stub)
    Mockito.when(i.next()).thenReturn("Hello").thenReturn("World");
    
    String result = i.next() + " " + i.next();
    assertEquals("Hello World", result);
  }
  
  @Test
  public void testWithArgs(){
    
    //Mock Class
    Comparable c = mock(Comparable.class);
    
    //Stubing a Mocked Class [when..thenReturn]
    when (c.compareTo("Test")).thenReturn(1);
    
    assertEquals(1, c.compareTo("Test"));
    
  }
  
  //Using Matchers [Preffered]
  @Test
  public void testWithoutArgs(){
    //Mock Class
    Comparable c = Mockito.mock(Comparable.class);
    
    //Using Matchers
    when(c.compareTo(anyInt())).thenReturn(-1);
    
    assertEquals(-1, c.compareTo(5));
  }
  
  //Using Mockito.doReturn [Optional]
  @Test
  public void testWithoutArgsNew(){
    
    //Mock Class
    Comparable c = mock(Comparable.class);
    
    //Using doReturn
    doReturn(-1).when(c).compareTo(anyInt());
    
    assertEquals(-1, c.compareTo(5));
    
  }
  
  /*
   * Verifying (OutputStreamWriter) osw rethrows when mock (OutputStream)
   * throws an exception
   */
  
  @Test(expected=IOException.class)
  public void testRethrow() throws IOException{
    
    OutputStream mock = mock(OutputStream.class);
    OutputStreamWriter osw = new OutputStreamWriter(mock);
    
    doThrow(new IOException()).when(mock).close();
    osw.close();
  }
  
  
  /*
   * Verifying OutputStreamWriter propagates close method call to OutputStream Mock
   * Object.
   */
  @Test
  public void testOnClose() throws IOException{
    OutputStream mock = mock(OutputStream.class);
    
    OutputStreamWriter osw = new OutputStreamWriter(mock);
    osw.close();
    
    verify(mock).close();
  }
  

}