如何使用Mockito或Powermock模拟局部变量

Z时代
2024-01-10
分类：问答

我有这样的情况

InputStreamReader reader = new InputStreamReader(getFileAsStream(resourceResolver, iconpath));
                BufferedReader bReader = new BufferedReader(reader);

到目前为止我一直在嘲笑

getFileAsStream(resourceResolver, iconpath)

现在我得到一个读者

 BufferedReader bReader = new BufferedReader(reader);

但是当我执行此行时，我得到null并且无法前进

  while ((iconEntry = bReader.readLine()) != null)

请告诉我如何嘲笑这个。请注意，我无法更改我的主要代码，因此在我的情况下，Mockito文档中存在的解决方案无效

测试码

@RunWith(PowerMockRunner.class)
@PrepareForTest({ FrameworkUtil.class, LoggerFactory.class })
public class IconPreviewServletTest {
    private IconPreviewServlet iconPreviewServlet;
    private SlingHttpServletRequest request;
    private SlingHttpServletResponse response;
    private Bundle bundle;
    private BundleContext bundleContext;
    private ServiceReference factoryRef;
    private CommonService resolverFactory;
    private PrintWriter out;
    private ResourceResolver resourceResolver;
    private Resource resource;
    private Node node;
    private Node jcrContent;
    private javax.jcr.Property property;
    private Binary binary;
    private InputStream stream;
    private InputStreamReader inputReader;
    private BufferedReader reader;
    @Before
    public void setUp() throws IOException, PathNotFoundException,
            RepositoryException {
        init();
    }
    private void init() throws IOException, PathNotFoundException,
            RepositoryException {
        request = mock(SlingHttpServletRequest.class);
        response = mock(SlingHttpServletResponse.class);
        bundleContext = mock(BundleContext.class);
        factoryRef = mock(ServiceReference.class);
        resolverFactory = mock(CommonService.class);
        out = mock(PrintWriter.class);
        resourceResolver = mock(ResourceResolver.class);
        resource = mock(Resource.class);
        node = mock(Node.class);
        jcrContent = mock(Node.class);
        property = mock(Property.class);
        binary = mock(Binary.class);
        stream=IOUtils.toInputStream("some test data for my input stream");
        reader = mock(BufferedReader.class);
        inputReader=mock(InputStreamReader.class);
        bundle = mock(Bundle.class);
        mockStatic(FrameworkUtil.class);
        mockStatic(LoggerFactory.class);
        Logger log = mock(Logger.class);
        when(LoggerFactory.getLogger(IconPreviewServlet.class)).thenReturn(log);
        when(FrameworkUtil.getBundle(CommonService.class)).thenReturn(bundle);
        when(bundle.getBundleContext()).thenReturn(bundleContext);
        when(bundleContext.getServiceReference(CommonService.class.getName()))
                .thenReturn(factoryRef);
        when(bundleContext.getService(factoryRef)).thenReturn(resolverFactory);
        when(request.getParameter("category")).thenReturn("category");
        when(request.getParameter("query")).thenReturn("query");
        when(response.getWriter()).thenReturn(out);
        when(request.getResourceResolver()).thenReturn(resourceResolver);
        when(
                resourceResolver
                        .getResource("/etc/designs/resmed/icons/category/icons.txt"))
                .thenReturn(resource);
        when(resource.adaptTo(Node.class)).thenReturn(node);
        when(node.getNode("jcr:content")).thenReturn(jcrContent);
        when(jcrContent.getProperty("jcr:data")).thenReturn(property);
        when(property.getBinary()).thenReturn(binary);
        when(binary.getStream()).thenReturn(stream);
    }

回答：

要使此工作正常进行，您需要使用Powermockito来拦截构造函数调用（新的InputStreamReader（…），新的BufferedReader（…）），以便返回模拟。下面是一个示例。在您的情况下，仅拦截新的BufferedReader调用就足够了。

假设以下是您要测试的代码：

package test;
import java.io.*;
public class SUT {
    public String doSomething() throws IOException {
        InputStreamReader reader =
                new InputStreamReader(getFileAsStream(null, null));
        BufferedReader bReader =
                new BufferedReader(reader);
        return bReader.readLine();
    }
    private InputStream getFileAsStream(Object resourceResolver, Object iconPath)
            throws FileNotFoundException {
        return new ByteArrayInputStream("".getBytes());
    }
}

以下测试代码是如何拦截构造函数调用的示例：

package test;
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 java.io.BufferedReader;
import java.io.InputStreamReader;
import static org.junit.Assert.assertEquals;
import static org.powermock.api.mockito.PowerMockito.doReturn;
import static org.powermock.api.mockito.PowerMockito.mock;
@RunWith(PowerMockRunner.class)
@PrepareForTest({ SUT.class })
public class SUTTest {
    @Test
    public void doSomethingReturnsValueFromBufferedReader() throws Exception {
        // Arrange
        SUT sut = new SUT();
        InputStreamReader inputStreamReaderMock = mock(InputStreamReader.class);
        BufferedReader bufferedReaderMock = mock(BufferedReader.class);
        // Set your mocks up to be returned when the new ...Reader calls 
        // are executed in sut.doSomething()
        PowerMockito.whenNew(InputStreamReader.class).
                     withAnyArguments().thenReturn(inputStreamReaderMock);
        PowerMockito.whenNew(BufferedReader.class).
                     withArguments(inputStreamReaderMock).
                     thenReturn(bufferedReaderMock);
        // Set the value you want bReader.readLine() to return 
        // when sut.doSomething() executes
        final String bufferedReaderReturnValue = "myValue";
        doReturn(bufferedReaderReturnValue).when(bufferedReaderMock).readLine();
        // Act
        String result = sut.doSomething();
        // Assert
        assertEquals(bufferedReaderReturnValue, result);
    }
}