如何从模拟路径加载模拟文件

Question

我正在尝试为一个尝试从磁盘获取文件并将其流式传输的函数编写单元测试：

public InputStream downloadFile(String folderName, String fileName) throws FileNotFoundException {
    File name = Paths.get("/tmp/portal", folderName, fileName).toFile();

    return new FileInputStream(name);
  }

我的尝试代码

 @InjectMock MyService myService;
   
    @TempDir
        Path mockDirectory;
     @Test
        void downloadFile() throws IOException {
     Path mockFile = mockDirectory.resolve("testFile");
            Files.createFile(mockFile);
     String folderName= mockFile.subpath(5, 6).toString();
     String filename= mockFile.getFileName().toString();
        InputStream inputStreamResult = myService.downloadFile(folderName, filename);
    }

错误是

文件：testFile 不存在

Answer 1

您收到错误testFile dont exsits，因为在downloadFile 方法中有一个硬编码路径"/tmp/portal"。

以下是下载文件的单元测试示例：

interface Service {
    Cipher getDecryptCipher();
}

class FileDownloader {

    private final Service service;

    public FileDownloader(Service service) {
        this.service = service;
    }

    public InputStream downloadFile(String folderName, String fileName) throws FileNotFoundException {
        File file = Paths.get(folderName, fileName).toFile();
        return new CipherInputStream(new FileInputStream(file), service.getDecryptCipher());
    }
}

@ExtendWith(MockitoExtension.class)
class FileDownloaderTest {

    @TempDir
    Path directory;
    @Mock
    Service service;
    @Mock
    Cipher cipher;
    @InjectMocks
    FileDownloader fileDownloader;

    @Test
    void fileContentIsDownloaded() throws IOException {

        String testFileName = "testFile";
        String testFileContent = "test text";

        Path testFile = directory.resolve(testFileName);
        Files.createFile(testFile);
        Files.write(testFile, testFileContent.getBytes());
        when(service.getDecryptCipher()).thenReturn(cipher);

        InputStream actualInputStream = fileDownloader.downloadFile(directory.toString(), testFileName);

        CipherInputStream expectedInputStream = new CipherInputStream(new ByteArrayInputStream(testFileContent.getBytes()), cipher);
        assertThat(actualInputStream).hasSameContentAs(expectedInputStream);
    }
}