Java一分钟之-PowerMock：静态方法与私有方法测试

import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import static org.junit.Assert.assertEquals;
import static org.powermock.api.mockito.PowerMockito.*;
 
@RunWith(PowerMockRunner.class)
@PrepareForTest(StaticAndPrivateMethodTest.class)
public class StaticAndPrivateMethodTest {
 
    @Test
    public void testStaticMethod() {
        // 使用PowerMockito.mockStatic方法来模拟静态方法
        mockStatic(StaticAndPrivateMethodTest.class);
        when(StaticAndPrivateMethodTest.staticMethod()).thenReturn("mocked static");
 
        assertEquals("mocked static", StaticAndPrivateMethodTest.staticMethod());
    }
 
    @Test
    public void testPrivateMethod() throws Exception {
        // 使用PowerMockito.spy方法来创建一个对象的模拟
        StaticAndPrivateMethodTest testSpy = spy(new StaticAndPrivateMethodTest());
        // 使用Whitebox.setInternalState来设置私有字段的值
        Whitebox.setInternalState(testSpy, "privateField", "mocked private");
 
        when(testSpy, method(StaticAndPrivateMethodTest.class, "privateMethod")).thenCallRealMethod();
        assertEquals("mocked private", testSpy.privateMethod());
    }
 
    public static String staticMethod() {
        return "original static";
    }
 
    private String privateMethod() {
        return (String) Whitebox.getInternalState(this, "privateField");
    }
 
    private String privateField = "original private";
}

这个代码示例展示了如何使用PowerMock进行静态方法和私有方法的测试。在第一个测试中，我们模拟了静态方法的行为，使其返回一个固定的mock值。在第二个测试中，我们通过PowerMock的Whitebox类间接设置了私有字段的值，并且模拟了私有方法，使其在调用时返回这个mock值。