Spring测试静态方法打桩-PowerMockito及SpringBootTest结合使用

Mockito无法对静态方法进行Mock，如果需要Mock静态方法，需要使用到PowerMockito。

1. Maven依赖

<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-api-mockito</artifactId>
    <version>1.7.1</version>
</dependency>

<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-module-junit4</artifactId>
    <version>1.7.1</version>
</dependency>

2. 单元测试

单元测试时，需要使用PowerMockRunner及PrepareForTest两个注解：

@RunWith(PowerMockRunner.class)
@PrepareForTest({SysCache.class})
public class ModelAssistantServiceUTTest {
    private ModelAssistantService modelAssistantService;

    private ModelAssistantDao modelAssistantDao;

    private String tenantId;
    private String deviceTypeId;

    @Before
    public void before() throws NoSuchFieldException, IllegalAccessException {
        modelAssistantService = new ModelAssistantServiceImpl();
        modelAssistantDao = MockUtil.mockField(ModelAssistantServiceImpl.class,
                modelAssistantService, "modelAssistantDao", ModelAssistantDao.class);

        this.tenantId = "158";
        this.deviceTypeId = "3000";

        // SysCache打桩
        PowerMockito.mockStatic(SysCache.class);
        PowerMockito.when(SysCache.getTargetDbCache(BDDMockito.anyLong(), BDDMockito.anyString(), BDDMockito.any()))
                .thenReturn(new TargetDB());
    }
}

如果不使用PrepareForTest，将会报以下错误：

... not prepared for test.

而使用PrepareForTest注解时，必须要使用PowerMockRunner才会生效！

3 与SpringBootTest一起使用

SpringBootTest必须要使用SpringRunner才能生效；但RunWith没有办法指定多个，可以通过PowerMockRunnerDelegate来解决这个问题：

@RunWith(PowerMockRunner.class)
@PowerMockRunnerDelegate(SpringRunner.class)
@PrepareForTest(HttpRequest.class)
@SpringBootTest

单单添加了以上四个注解还是不够，在执行的时候会报以下错误：

java.lang.LinkageError: loader constraint violation: loader (instance of org/powermock/core/classloader/MockClassLoader) previously initiated loading for a different type with name "javax/management/MBeanServer"

此时需要通过PowerMockIgnore注解来解决：

@PowerMockIgnore( {"javax.management.*"})

再次执行，发现又报以下错误：

Caused by: java.security.NoSuchAlgorithmException: class configured for SSLContext: sun.security.ssl.SSLContextImpl$TLSContext not a SSLContext

需要在PowerMockIgnore再添加一个忽略项：

@PowerMockIgnore( {"javax.management.*", "javax.net.ssl.*"})

因此，最终测试类上的注解如下：

@RunWith(PowerMockRunner.class)
@PowerMockRunnerDelegate(SpringRunner.class)
@PowerMockIgnore( {"javax.management.*", "javax.net.ssl.*"})
@PrepareForTest(HttpRequest.class)
@SpringBootTest

这样之后测试类终于可以成功启动了。