在沒有現有文件的情況下使用Mockito/PowerMockito模擬FileInputStream

Question

我正在爲使用FileInputStream的方法編寫JUnit，並且在constructor中只傳遞文件名。該文件是作爲servlet請求的一部分創建的，並且此文件不存儲在任何位置。

我想MockFileInputStream使用PowerMockito，這樣它給了我一個模擬的文件對象。不幸的是我得到FileNotFoundException這是有效的，但我不知道如何測試這種方法，然後因爲該文件不存在。被測

方法：

public String viewReport() throws Exception { 
    this.inputStream = new FileInputStream(DOCUSIGN_REPORT_FILE); 

    try { 
     boolean returnReport = validateRequest(); 
     if (returnReport) { 
      intgList = this.generateViewIntegrationReportData(getESignUIConfig()); 
      this.createCSVFile(intgList, new FileWriter(DOCUSIGN_REPORT_FILE)); 
     } else { 
      failureResponse(msgs, 400); 
      return null; 
     } 
    } catch (Exception e) { 
     e.printStackTrace(); 
     msgs.add(new Message(ESignatureIntegrationMessageTypeEnum.MESSAGE_TYPE_ERROR, 
        UiIntegrationKeyConstants.UI_INTEGRATION_ERROR_CODE_500, UiIntegrationKeyConstants.UI_INTEGRATION_ERROR_TEXT_SERVICE_ERROR)); 
     failureResponse(msgs, 500); 
     return null; 
    } 

    return UiIntegrationKeyConstants.REPORT_REPSONSE; 
} 

的JUnit至今測試。

@Test 
public void testViewReport() throws Exception { 
    Map<String, Object> actionMap = new HashMap<>(); 
    actionMap.put("application", "ESignatureIntegrationAction"); 

    ActionContext.setContext(new ActionContext(actionMap)); 

    FileInputStream inputStream = Mockito.mock(FileInputStream.class); 
    PowerMockito.whenNew(FileInputStream.class).withAnyArguments().thenReturn(inputStream); 

    action = new ESignatureIntegrationAction(); 
    action.viewReport(); 
} 

我得到一個exception當代碼達到new FileInputStream(DOCUSIGN_REPORT_FILE);

感謝您的幫助。

Answer 1

我建議以允許在沒有模擬框架的情況下進行測試的方式重構代碼。

它可能看起來有點像這樣：

public class YourClass { 

    // ... 

    public String viewReport() { 
     try { 
      boolean isValidRequest = validateRequest(); 
      if (isValidRequest) { 
       IntegrationReportCsvFileHandler fileHandler = new IntegrationReportCsvFileHandler(); 
       IntegrationReportData inputData = fileHandler.readData(new FileInputStream(DOCUSIGN_REPORT_FILE)); 

       IntegrationReportGenerator generator = new IntegrationReportGenerator(); 
       IntegrationReportData outputData = generator.processData(inputData, getESignUIConfig()); 

       fileHandler.writeReport(outputData, new FileWriter(DOCUSIGN_REPORT_FILE)); 
      } else { 
       failureResponse(msgs, 400); 
       return UiIntegrationKeyConstants.FAILURE_RESPONSE; 
      } 
     } catch (Exception e) { 
      e.printStackTrace(); 
      msgs.add(new Message(ESignatureIntegrationMessageTypeEnum.MESSAGE_TYPE_ERROR, 
         UiIntegrationKeyConstants.UI_INTEGRATION_ERROR_CODE_500, UiIntegrationKeyConstants.UI_INTEGRATION_ERROR_TEXT_SERVICE_ERROR)); 
      failureResponse(msgs, 500); 
      return UiIntegrationKeyConstants.FAILURE_RESPONSE; 
     } 

     return UiIntegrationKeyConstants.REPORT_RESPONSE; 
    } 

    // ... 

} 

public class IntegrationReportData { 
    // your custom data structure 
    // may as well just be a List<Data> 
    // may be different for input and output 
} 

public class IntegrationReportException extends Exception { 
    // your custom exception 
    public IntegrationReportException(String message) { super(exception); } 
} 

public class IntegrationReportGenerator { 

    public IntegrationReportData processData(IntegrationReportData data, ESignConfig config) throws IntegrationReportException { 
     // here's your logic that requires testing 
    } 

} 

public class IntegrationReportCsvFileHandler { 

    public IntegrationReportData readData(InputStream input) throws IOException { 
     // read data from given input stream 
    } 

    public void writeData(IntegrationReportData data, OutputStreamWriter outputWriter) throws IOException { 
     // write data to given output stream 
    } 

} 

這樣的IntegrationReportGenerator會容易測試。