Question

我（仍然）正在尝试使用PowerMockito（bar(Alpha, Baz)为bar(Xray, Baz)）来检查bar(Xray, Baz)是否private，而不是实际调用后者，因为我的MCVE下面的课程Foo。（我经历了同一个班级earlier，Foo中的所有方法都是public - 如果你有一个似曾相识的话......）

public class Foo {
    private String bar(Xray xray, Baz baz) {
        return "Xray";
    }

    private String bar(Zulu zulu, Baz baz) {
        return "Zulu";
    }

    public String bar(Alpha alpha, Baz baz) {
        if(alpha.get() instanceof Xray) {
            return bar((Xray)alpha.get(), baz);
        } else if(alpha.get() instanceof Zulu) {
            return bar((Zulu)alpha.get(), baz);
        } else {
            return null;
        }
    }
}

当我尝试运行下面的测试时，我从PowerMock获得了一个NPE：

@RunWith(PowerMockRunner.class)
// @PrepareOnlyThisForTest(Foo.class) // we aren't looking at the byte code, I think
public class FooTest {

    @Test
    public void testBar_callsBarWithXray() throws Exception {
        Baz baz = new Baz(); //POJOs
        Alpha alpha = new Alpha();
        alpha.set(new Xray());

        Foo foo = new Foo();
        Foo stub = spy(foo); // using Mockito, as it's neither final nor "not spyable"

        // NPE at org.powermock.api.mockito.internal.expectation.PowerMockitoStubberImpl.addAnswersForStubbing(PowerMockitoStubberImpl.java:67)
        PowerMockito.doReturn("ok").when(stub, "bar", Xray.class, Baz.class);

        stub.bar(alpha, baz);
        // Testing if bar(Xray, Baz) was called by bar(Alpha, Baz)
        PowerMockito.verifyPrivate(foo).invoke("bar", Xray.class, Baz.class);
        // Mockito's equivalent for a public method: verify(stub, times(1)).bar(any(Xray.class), any(Baz.class));
    }
}

如果我将存根设为PowerMockito.spy(foo)，我会得到IllegalArgumentException: argument type mismatch at org.powermock.reflect.internal.WhiteboxImpl.performMethodInvocation(WhiteboxImpl.java:2014)。（它与NPE在同一条线上冒泡。）

我正在使用Mockito-core 1.9.5，PowerMock 1.5.4（module-junit4和api-mockito）和JUnit 4.11。

我需要更改什么来阻止异常被抛出？我怎样才能使这个测试工作？（除了testing that我班级的工作，而不是如何 ...... ;-)）

Answer 1

在设定期望时，我们必须使用精确的参数匹配器。在你的情况下，它是 Matchers.any（Xray.class），Matchers.any（Baz.class）

我已经修改了你的代码，并在测试方法的输出对象上添加了assert语句。

@RunWith(PowerMockRunner.class)
//@PrepareOnlyThisForTest(Foo.class) // we aren't looking at the byte code, I think
 public class FooTest {

   @Test
   public void testBar_callsBarWithXray() throws Exception {
       Baz baz = new Baz(); //POJOs
       Alpha alpha = new Alpha();
       alpha.set(new Xray());

       Foo foo = new Foo();
       Foo stub = PowerMockito.spy(foo); // using Mockito, as it's neither final nor "not spyable"

      // NPE at org.powermock.api.mockito.internal.expectation.PowerMockitoStubberImpl.addAnswersForStubbing(PowerMockitoStubberImpl.java:67)
      PowerMockito.doReturn("ok").when(stub, "bar", Matchers.any(Xray.class), Matchers.any(Baz.class));

      String res = stub.bar(alpha, baz);
      Assert.assertEquals("ok", res);

     //Testing if bar(Xray, Baz) was called by bar(Alpha, Baz)
     PowerMockito.verifyPrivate(stub).invoke("bar", Matchers.any(Xray.class), Matchers.any(Baz.class));
     // Mockito's equivalent for a public method: verify(stub, times(1)).bar(any(Xray.class), any(Baz.class));
   }
}

观察：当调用验证方法时，我们必须传递存根对象而不是实际对象，因为我们设置对存根对象的期望。当我添加assert语句来测试该方法时，您不必在存根上验证它是否正常工作。

<强>增加：我在public＆amp; amp;中添加了sysout语句。私有'bar'方法，当我再次测试时，我看到没有打印公共栏方法的sysout语句。这意味着上面的代码只模拟了公共方法，而不是私有方法。

为了模拟私有'bar'方法，我尝试使用另一种使用MemberMatcher.method进行模拟的方法，该方法完美无缺。

import org.powermock.api.support.membermodification.MemberMatcher;

@RunWith(PowerMockRunner.class)
@PrepareForTest(Foo.class) // we need this
public class FooTest {

@Test
 public void testBar_callsBarWithXray() throws Exception {
     Baz baz = new Baz(); //POJOs
     Alpha alpha = new Alpha();
     alpha.set(new Xray());

     Foo stub = PowerMockito.spy(new Foo());

     PowerMockito.doReturn("ok")
        .when(stub,
                MemberMatcher.method(Foo.class,
                        "bar",
                        Xray.class, Baz.class))
        .withArguments(Matchers.any(Xray.class), Matchers.any(Baz.class));

     String res = stub.bar(alpha, baz);

     Assert.assertEquals("ok", res);

     //Testing if bar(Xray, Baz) was called by bar(Alpha, Baz)
     PowerMockito.verifyPrivate(stub).invoke("bar", Matchers.any(Xray.class), Matchers.any(Baz.class));
     // Mockito's equivalent for a public method: verify(stub, times(1)).bar(any(Xray.class), any(Baz.class));
 }

 output : public bar

测试方法也通过了。下面是具有sysouts的foo方法。

private String bar(Xray xray, Baz baz) {
    System.out.println("private bar");
    return "Xray";
}

public String bar(Alpha alpha, Baz baz) {

    System.out.println("public bar");

    if(alpha.get() instanceof Xray) {
        return bar((Xray)alpha.get(), baz);
    } else if(alpha.get() instanceof Zulu) {
        return bar((Zulu)alpha.get(), baz);
    } else {
        return null;
    }
}

尝试存根私有重载方法时，PowerMockito会抛出NullPointerException

1 个答案: