java - 想要但未调用 : Mockito PrintWriter

Question

您好，我正在开发一个项目，并使用 PrintWriter 类打开和写入文件。但是当我编写相同的测试用例时，它在第 153 行给出以下错误

Wanted but not invoked:
  mockPrintWriter.println("ID    url1
  ");
 -> at x.y.z.verify(ProcessImageDataTest.java:153)
 Actually, there were zero interactions with this mock.

代码:(使用Lombok库)

ProcessImageData.java

@Setter
@RequiredArgsConstructor
public class ProcessImageData implements T {
    private final File newImageDataTextFile;

   @Override
    public void execute() {
       LineIterator inputFileIterator = null;
       try {
        File filteredImageDataTextFile = new File(filteredImageDataTextFilepath);

          PrintWriter writer = new PrintWriter(newImageDataTextFile);
          inputFileIterator = FileUtils.lineIterator(filteredImageDataTextFile, StandardCharsets.UTF_8.displayName());
          while (inputFileIterator.hasNext()) {
                    if(someCondition)
           **Line51**           writer.println(imageDataFileLine);
                    //FileUtils.writeStringToFile(newImageDataTextFile, imageDataFileLine + NEWLINE, true);
                }
            }          

      } catch (Exception e) {

      } finally {
          LineIterator.closeQuietly(inputFileIterator);
 **LINE63**         writer.close();
      }
  }

ProcessImageDataTest.java

@RunWith(PowerMockRunner.class)
@PrepareForTest({ ProcessImageData.class, FileUtils.class, Printwriter.class })
public class ProcessImageDataTest {

private ProcessImageData processImageData;

private static final String FILTERED_IMAGE_DATA_TEXT_FILE_PATH = "filteredFilepath";
private File FILTEREDFILE = new File(FILTERED_PATH);
private static final File IMAGE__FILE = new File("imageFilePath");

private LineIterator lineIterator;
@Mock
private PrintWriter mockPrintWriter;

@Before
public void init() throws Exception {
    MockitoAnnotations.initMocks(this);

    processImageData = new ProcessImageData(Palettes_file, FILTERED_PATH, IMAGE_FILE);

    PowerMockito.mockStatic(FileUtils.class);
    PowerMockito.whenNew(PrintWriter.class).withArguments(IMAGE_FILE).thenReturn(mockPrintWriter);

    PowerMockito.when(FileUtils.lineIterator(FILTERED_FILE, StandardCharsets.UTF_8.displayName())).thenReturn(lineIterator);
    PowerMockito.when(lineIterator.hasNext()).thenReturn(true, true, false);

}

@Test
public void testTaskWhenIDInDBAndStale() throws IOException {
    PowerMockito.when(lineIterator.nextLine()).thenReturn(ID2 + SPACE + URL1, ID1 + SPACE + URL2);

    processImageData.execute();

    List<String> exepctedFileContentOutput = Arrays.asList(ID2 + SPACE + URL1 + NEWLINE);
    verify(exepctedFileContentOutput, 1, 1);
}


@Test
public void testTaskWhenIDNotInDB() throws IOException {
    PowerMockito.when(lineIterator.nextLine()).thenReturn(ID2 + SPACE + URL1, ID3 + SPACE + URL2);

    processImageData.execute();

    List<String> exepctedFileContentOutput = Arrays.asList(ID3 + SPACE + URL2 + NEWLINE);
    verify(exepctedFileContentOutput, 1, 1);
}

private void verify(List<String> exepctedFileContentOutput, int fileWriteTimes, int fileReadTimes) throws IOException {
    for (String line : exepctedFileContentOutput){
**Line153**                     Mockito.verify(mockPrintWriter,  Mockito.times(fileWriteTimes)).print(line);  
    }

    PowerMockito.verifyStatic(Mockito.times(fileReadTimes));
    FileUtils.lineIterator(FILTERED_IMAGE_DATA_TEXT_FILE, StandardCharsets.UTF_8.displayName());
}

}

我还模拟了 PrintWriter 的一个新运算符，使用 bean 注入(inject)。我做错了什么？我坚持了很长时间却没有收到错误？如有任何帮助，我们将不胜感激。

更新:

我做了下面建议的更改并更新了代码，但现在我收到错误:

Wanted but not invoked: mockPrintWriter.print("ASIN2 url1 "); -> 
at softlines.ctl.ruleExecutor.tasks.ProcessImageDataTest.verify‌​(ProcessImageDataTes‌​t.java:153) 
However, there were other interactions with this mock: -> at softlines.ctl.ruleExecutor.tasks.ProcessImageData.execute(Pr‌​ocessImageData.java:‌​51) ->  
at  softlines.ctl.ruleExecutor.tasks.ProcessImageData.execute(Pr‌​ocessImageData.java:‌​51) -> 
at softlines.ctl.ruleExecutor.tasks.ProcessImageData.execute(Pr‌​ocessImageData.java:‌​58) –

Answer 1

我在您的测试中发现 3 个问题:

1. 您不会尝试模拟正确的构造函数，实际上，在execute方法中，您仅使用创建您的PrintWriter当您尝试模拟具有 2 个参数的构造函数时，一个参数为 File 类型，其中一个参数为 File 类型，另一个参数为 File 类型字符串。

所以代码应该是:

PowerMockito.whenNew(PrintWriter.class)
    .withArguments(IMAGE_FILE)
    .thenReturn(mockPrintWriter);

为了能够模拟构造函数，您需要准备创建实例的类，在本例中为 ProcessImageData，因此您需要添加 ProcessImageData.class > 在注释@PrepareForTest中。 (我不确定那里是否需要 ProcessImageDataTest.class)

字段lineIterator应使用@Mock进行注释。

您应该直接验证 println 不使用新行，而不是使用新行验证 print ，这样更不容易出错.

<小时/>

我简化了你的代码来展示这个想法。

假设ProcessImageData是:

public class ProcessImageData {

    private final File newImageDataTextFile;

    public ProcessImageData(final File newImageDataTextFile) {
        this.newImageDataTextFile = newImageDataTextFile;
    }

    public void execute() throws Exception{
        try (PrintWriter writer = new PrintWriter(newImageDataTextFile)) {
            LineIterator inputFileIterator = FileUtils.lineIterator(
                newImageDataTextFile, StandardCharsets.UTF_8.displayName()
             );
            while (inputFileIterator.hasNext()) {
                writer.println(inputFileIterator.nextLine());
            }
        }
    }
}

我的单元测试将是:

@RunWith(PowerMockRunner.class)
@PrepareForTest({ProcessImageData.class, FileUtils.class})
public class ProcessImageDataTest {

    private File file = new File("imageFilePath");

    private ProcessImageData processImageData;
    @Mock
    private PrintWriter mockPrintWriter;
    @Mock
    private LineIterator lineIterator;

    @Before
    public void init() throws Exception {
        MockitoAnnotations.initMocks(this);

        processImageData = new ProcessImageData(file);
        PowerMockito.whenNew(PrintWriter.class)
            .withArguments(file)
            .thenReturn(mockPrintWriter);
        PowerMockito.mockStatic(FileUtils.class);
        PowerMockito.when(
            FileUtils.lineIterator(file, StandardCharsets.UTF_8.displayName())
        ).thenReturn(lineIterator);
        PowerMockito.when(lineIterator.hasNext()).thenReturn(true, true, false);
    }

    @Test
    public void testExecute() throws Exception {
        PowerMockito.when(lineIterator.nextLine()).thenReturn("Foo", "Bar");
        processImageData.execute();
        Mockito.verify(mockPrintWriter,  Mockito.times(1)).println("Foo");
        Mockito.verify(mockPrintWriter,  Mockito.times(1)).println("Bar");
    }
}

更多详情请参阅How to mock construction of new objects .

<小时/>

how can I add verification in unit test for writer.close?

一种方法可能是通过将下一行添加到单元测试中来简单地检查 close() 是否被调用:

Mockito.verify(mockPrintWriter,  Mockito.times(1)).close();