Mockito 使用 PowerMock 让 Mockito 支持静态方法


PowerMock 是一个增强库,用来增加 Mockito 、EasyMock 等测试库的功能。

Mockito 默认是不支持静态方法

比如我们在 ExampleService 类中定义静态方法 add:

public class ExampleService {

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

    }

尝试给静态方法打桩,会报错:

import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.junit.MockitoJUnitRunner;

import static org.mockito.Mockito.*;

@RunWith(MockitoJUnitRunner.class)
public class MockitoDemo {

    @Test
    public void test() {

        // 会报错
        when(ExampleService.add(1, 2)).thenReturn(100);

    }

}

可以用 Powermock 弥补 Mockito 缺失的静态方法 mock 功能

在 build.gradle 中配置以下依赖:

dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.12'
    testCompile group: 'org.mockito', name: 'mockito-core', version: '2.25.1'

    // PowerMock 相关依赖
    testCompile group: 'org.powermock', name: 'powermock-core', version: '2.0.0'
    testCompile group: 'org.powermock', name: 'powermock-module-junit4', version: '2.0.0'
    testCompile group: 'org.powermock', name: 'powermock-api-mockito2', version: '2.0.0'
}

示例:

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

import static org.mockito.Mockito.*;

@RunWith(PowerMockRunner.class)     // 这是必须的
@PrepareForTest(ExampleService.class)  // 声明要处理 ExampleService
public class MockitoDemo {
    @Test
    public void test() {

        PowerMockito.mockStatic(ExampleService.class);  // 这也是必须的

        when(ExampleService.add(1, 2)).thenReturn(100);

        Assert.assertEquals(100, ExampleService.add(1, 2));
        Assert.assertEquals(0, ExampleService.add(2, 2));

    }
}

PowerMockRunner 支持 Mockito 的 @Mock 等注解

上面我们用了 PowerMockRunner ,MockitoJUnitRunner 就不能用了。但不要担心, @Mock 等注解还能用。

import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.powermock.modules.junit4.PowerMockRunner;

import java.util.Random;

import static org.mockito.Mockito.*;

@RunWith(PowerMockRunner.class)
public class MockitoDemo {

    @Mock
    private Random random;

    @Test
    public void test() {

        when(random.nextInt()).thenReturn(1);
        Assert.assertEquals(1,  random.nextInt());

    }
}


(本文完)


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