class to test mocking of private and public static method

MockStaticMethodTest.java

/* File:    MockStaticMethodTest.java
 * Created: 5/17/2019
 * Author:  Sabbir Manandhar
 *
 * Copyright (c) 2019 Hogwart Inc.
 */

package com.hogwart;

import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

//=================================================================================================

/**
 * @author Sabbir Manandhar
 * @version 1.0
 */
@RunWith(PowerMockRunner.class)
@PrepareForTest({MockStaticMethod.class})
public class MockStaticMethodTest {
  @Test
  public void testDiff() throws Exception {
    PowerMockito.mockStatic(MockStaticMethod.class);
    PowerMockito.doReturn(3).when(MockStaticMethod.class, "diff", Mockito.anyInt(), Mockito.anyInt());

    MockStaticMethod obj = new MockStaticMethod();
    Assert.assertEquals(3, obj.getResult(0, 0, false));
    Assert.assertEquals(3, obj.getResult(1, 2, false));
  } // testDiff

  //-----------------------------------------------------------------------------------------------

  @Test
  public void testSumWrong() throws Exception {
    PowerMockito.mockStatic(MockStaticMethod.class);
    PowerMockito.doReturn(100).when(MockStaticMethod.sum(Mockito.anyInt(), Mockito.anyInt()));

    MockStaticMethod obj = new MockStaticMethod();
    Assert.assertEquals(100, obj.getResult(0, 0, true));
    Assert.assertEquals(100, obj.getResult(1, 2, true));
  } // testSumWrong

  //-----------------------------------------------------------------------------------------------

  @Test
  public void testSumRight() throws Exception {
    PowerMockito.mockStatic(MockStaticMethod.class);
    PowerMockito.when(MockStaticMethod.sum(Mockito.anyInt(), Mockito.anyInt())).thenReturn(100);

    MockStaticMethod obj = new MockStaticMethod();
    Assert.assertEquals(100, obj.getResult(0, 0, true));
    Assert.assertEquals(100, obj.getResult(1, 2, true));
  } // testSumRight

  //-----------------------------------------------------------------------------------------------

  @Test
  public void testSumRight2() throws Exception {
    PowerMockito.mockStatic(MockStaticMethod.class);
    PowerMockito.doReturn(100).when(MockStaticMethod.class, "sum", Mockito.anyInt(), Mockito.anyInt());

    MockStaticMethod obj = new MockStaticMethod();
    Assert.assertEquals(100, obj.getResult(0, 0, true));
    Assert.assertEquals(100, obj.getResult(1, 2, true));
  } // testSumRight2

} // MockStaticMethodTest

//=================================================================================================

class MockStaticMethod {

  public int getResult(int a, int b, boolean sum) {
    if (sum) {
      return sum(a, b);
    } else {
      return diff(a, b);
    }
  } // getResult

  //-----------------------------------------------------------------------------------------------

  public static int sum(int a, int b) {
    return a + b;
  } // sum

  //-----------------------------------------------------------------------------------------------

  private static int diff(int a, int b) {
    return a - b;
  } // diff

} // MockStaticMethod