java - 使用 powermockito 模拟静态方法

Question

我有一个类 Engine.class

静态函数

public static  HashMap<String, String> loadLanguageCodeFile(HashMap<String,String> hash_map) {
    SystemSettings settings;
    FileReader fr = null;
    BufferedReader br = null;
    try {
      settings = SystemSettings.GetInstance();
      String path = settings.getLangCodePath();
      fr = new FileReader(path + FILENAME);
      br = new BufferedReader(fr);
      String Line;
      while ((Line = br.readLine())!= null) {
        String[] lang_codes =  Line.split("\\s+");
        hash_map.put(lang_codes[0], lang_codes[1]);
      }
    } catch (IOException e) {
      log.error("MicrosoftEngine: Unable to load file.", e);
    } catch (WorldlingoException e){
      log.error("MicrosoftEngine:", e);
    }
    finally {
      try {
        if (fr != null) {
          fr.close();
        }
        if (br != null) {
          br.close();
        }
      } catch ( IOException e) {
        log.error("MicrosoftEngine : An error occured while closing a resource.", e);
      }
    }
   return hash_map;
  }

我正在尝试为此方法编写一个测试用例。 Systemsetting是另一个类和

settings = SystemSettings.GetInstance();
      String path = settings.getLangCodePath();

` 给出另一个类的实例并包含路径文件，如\var\log file in path 。

我正在尝试使用 mockito 编写测试用例。由于它是一个静态类，所以我使用了 powermockito。

@RunWith(PowerMockRunner.class)
@PrepareForTest({HttpClientBuilder.class,Engine.class, SystemSettings.class})

 public class EngineTest extends TestCase {

        public void testLoadLanguageCodeFile() throws Exception {
            PowerMockito.mockStatic(Engine.class);
            PowerMockito.mockStatic(SystemSettings.class);
            MicrosoftEngine MSmock = Mockito.mock(Engine.class);
            SystemSettings SystemSettingsMock = Mockito.mock(SystemSettings.class);
            Mockito.when(SystemSettingsMock.GetInstance()).thenReturn(SystemSettingsMock);
            HashMap<String, String> hash_map = new HashMap<String, String>();
            MSmock.loadLanguageCodeFile(hash_map);
    }

我无法调用上面的 loadLanguageCodeFile 方法。任何有关如何调用静态方法的建议都将不胜感激

Answer 1

你不应该 mock 被测对象。您模拟被测对象的依赖项，这些依赖项是完成测试所需的。

该代码还与文件读取器和缓冲区读取器等实现问题紧密耦合。

但是，如评论中所述，您希望在模拟设置提供的路径上测试文件的实际读取。

在那种情况下，您只需要模拟 SystemSettings 并且应该调用被测的实际成员

RunWith(PowerMockRunner.class)
@PrepareForTest({SystemSettings.class})
public class EngineTest extends TestCase {
    public void testLoadLanguageCodeFile() throws Exception {
        //Arrange
        String path = "Path to test file to be read";
        PowerMockito.mockStatic(SystemSettings.class);
        //instance mock
        SystemSettings settings = Mockito.mock(SystemSettings.class);
        Mockito.when(settings.getLangCodePath()).thenReturn(path);
        //mock static call
        Mockito.when(SystemSettings.GetInstance()).thenReturn(settings);
        HashMap<String, String> hash_map = new HashMap<String, String>();

        //Act
        HashMap<String, String> actual = Engine.loadLanguageCodeFile(hash_map);

        //Assert
        //perform assertion
    }
}

引用 Using PowerMock with Mockito: Mocking Static Metho