不能模仿FileInputStream

Question

我有过

@Component
public class CodesConverterService {    
private final FileInputStreamFactory fileInputStreamFactory;

public CodesConverterService(FileInputStreamFactory fileInputStreamFactory, YamlFactory yamlFactory) {
    this.fileInputStreamFactory = fileInputStreamFactory;

}
@EventListener(ApplicationReadyEvent.class)
    public void loadMappingsFromSource() {
        try {
            FileInputStream f = fileInputStreamFactory.getStream("mappingFile");
        } catch (Exception e) {
            throw new CodesConverterException("Can`t load mappings from source");
        }
    }

我的FileInputStreamFactory：

@Component
public class FileInputStreamFactory {

    public FileInputStream getStream(final String file) throws FileNotFoundException {
        return new FileInputStream(file);
    }
}

我的测验

@RunWith(SpringRunner.class)
public class CodesConverterServiceTest {

    @InjectMocks
    private CodesConverterService codesConverterService;

    @Mock
    private FileInputStreamFactory fileInputStreamFactory;

    @Mock
    private FileInputStream fileInputStream;
    @Test
    public void whenLoadMappingsFromSource_GoodPath() throws FileNotFoundException {
        when(fileInputStreamFactory.getStream("mappingFile")).thenReturn(fileInputStream);

        this.codesConverterService.loadMappingsFromSource();
    }

为什么我的f总是空的？我试过很多种变体。但它总是空的。我为FileInputStream创建了工厂，因为我不想在测试中使用PowerMock在新FileInputStream上模拟创建。

Answer 1

我明白了我同时使用@RunWith(SpringRunner.class)和MockitoAnnotations.initMocks(this);的错误是什么。如果两者都使用，那么mokcks已经创造了，但工作方式不正确。所以我刚删除了MockitoAnnotations.initMocks(this);

Answer 2

我在下面的例子中复制了你的测试，这个例子对我有用。

(用JUnit 4 & Mockito 3.0.0和2.28.2验证)

我唯一改变的是Runner，但根据您的评论，您已经这样做了。

我删除了示例中的注释，因为它们在使用MockitoJUnitRunner执行测试时不相关，并更改了loadMappingsFromSource的返回类型以轻松添加Assert.assertNotNull。我还用一个CodesConverterException替换了RuntimeException。

这些更改都不应影响测试本身。

mock for FileInputStream是正确创建的，即使只有带有参数的构造函数。

@RunWith(MockitoJUnitRunner.class)
public class CodesConverterServiceTest {

    class YamlFactory {
    }

    class FileInputStreamFactory {
        public FileInputStream getStream(final String file) throws FileNotFoundException {
            return new FileInputStream(file);
        }
    }

    static class CodesConverterService {    

        private final FileInputStreamFactory fileInputStreamFactory;

        public CodesConverterService(FileInputStreamFactory fileInputStreamFactory, YamlFactory yamlFactory) {
            this.fileInputStreamFactory = fileInputStreamFactory;
        }

        public FileInputStream loadMappingsFromSource() {
            try {
                return fileInputStreamFactory.getStream("mappingFile");
            } catch (Exception e) {
                throw new RuntimeException("Can`t load mappings from source");
            }
        }
    }

    @InjectMocks
    private CodesConverterService codesConverterService;

    @Mock
    private FileInputStreamFactory fileInputStreamFactory;

    @Mock
    private FileInputStream fileInputStream;

    @Test
    public void whenLoadMappingsFromSource_GoodPath() throws FileNotFoundException {

        Mockito.when(fileInputStreamFactory.getStream("mappingFile")).thenReturn(fileInputStream);
        Assert.assertNotNull(codesConverterService.loadMappingsFromSource());
    }
}

Answer 3

1)试试下面的代码：

        @Test
        public void itShouldReturnFileInputStream() {
            FileInputStreamFactory mockFileInputStreamFactory = mock(FileInputStreamFactory.class);
            FileInputStream  mockFileInputStream = mock(FileInputStream.class);
            Mockito.doReturn(mockFileInputStream).when(mockFileInputStreamFactory).getStream("fileName");
            CodesConverterService  codeConverterService = new CodesConverterService(mockFileInputStreamFactory);
            assertThatCode(() -> codeConverterService.codeConverterService()).doesNotThrowAnyException();
        }