测试 void 方法中的静态方法已被调用一次

Question

我需要一些测试方面的帮助。有以下方法：

    @PrePersist
    public void prePersist(Tag tag) {

        if (tagService.listUserTags(tag.getUser())
                .size() > Constants.Tags.maxPerUser) {
            TaskUtils.createTask(url, param);
        }
    }

我想测试一下TaskUtils.createTask()被调用了一次，但是我不想里面的代码被执行。我试过这样：

        @Test
        @PrepareForTest(TaskUtils.class)
        public void testPrePersistMethodWhenTagCountOverLimit() {
            [...]
            when(tags.size()).thenReturn(Constants.Tags.maxPerUser + 1);
            when (tagService.listUserTags(tag.getUser())).thenReturn(tags);

            PowerMockito.mockStatic(TaskUtils.class);
            PowerMockito.doNothing().when(TaskUtils.class, "createTask", Mockito.any(String.class), Mockito.any(String.class));                                            

            Method method = ClassUtils.getMethodWithAnnotation(TagListener.class, PrePersist.class);
            method.invoke(tagListener, tag); //here the prePersist method is called

            PowerMockito.verifyStatic( Mockito.times(1));

        }

但是方法TaskUtils.createTask()实际上是在执行doNothing的情况下执行的。堆栈跟踪的一部分：

java.lang.NullPointerException
    at fi.util.TaskUtils.createTask(TaskUtils.java:90)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.powermock.reflect.internal.WhiteboxImpl.performMethodInvocation(WhiteboxImpl.java:1873)
    at org.powermock.reflect.internal.WhiteboxImpl.doInvokeMethod(WhiteboxImpl.java:773)
    at org.powermock.reflect.internal.WhiteboxImpl.invokeMethod(WhiteboxImpl.java:753)
    at org.powermock.reflect.Whitebox.invokeMethod(Whitebox.java:466)
    at org.powermock.api.mockito.internal.expectation.PowerMockitoStubberImpl.when(PowerMockitoStubberImpl.java:106)
    at fi.intra.test.domain.listener.TestTagListener.testPrePersistMethodWhenTagCountOverLimit(TestTagListener.java:92)

有什么想法吗？

Answer 1

以下有效并且应该等同于您的情况：

我使用Gradle构建，并添加了以下依赖：

testCompile group: 'org.powermock', name: 'powermock-mockito-release-full', version: '1.6.4'

测试

package sojava.mocking;

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.assertj.core.api.Assertions.assertThat;
import static org.mockito.Mockito.times;
import static org.powermock.api.mockito.PowerMockito.*;

@RunWith(PowerMockRunner.class)
@PrepareForTest(MyData.class)
public class PowerMockitoTests {

    @Test
    public void static_method_when_mocked_does_nothing() throws Exception {
        int amount = 123;

        // Arrange
        mockStatic(MyData.class);
        doNothing().when(MyData.class, "increment", amount);

        // Action
        new MyDataWrapper().increment(amount);
        verifyStatic(times(1));
        MyData.increment(amount);

        // Assert
        assertThat(MyData.getCount()).isEqualTo(0);
    }
}

你见过这段代码吗？

new MyDataWrapper().increment(amount);
verifyStatic(times(1));
MyData.increment(amount);

这很尴尬，但这就是它的工作原理。想要测试一个静态方法被调用了多次？然后你调用那个方法，然后调用 verifyStatic()，然后再次调用那个静态方法。最后一次调用将触发检查。

Class 使用静态方法

package sojava.mocking;

public class MyDataWrapper {
    public void increment(int amount) {
        MyData.increment(amount);
    }
}

Class 包含静态方法

包 sojava.mocking;

public class MyData {

    private static int count = 0;

    private MyData() {
    }

    public static void increment(int amount) {
        count += amount;
    }

    public static int getCount() {
        return count;
    }
}

更多样本： 更多样本位于 Github page on the tests folder.

测试 void 方法中的静态方法已被调用一次

Testing that static method inside void method has been called once

junit

junit4

mockito

powermock

powermockito