java - Mockito 规则未应用

Question

我正在使用 Mockito 编写一个测试用例，在我看来，一个 Mockito 规则没有被定义。以下是我的场景。

public class DummyTest {
   private final String[] alphabet= {"a", "b", "c", "d", "e" };
   private final String[] numeric= {"1", "2", "3", "4", "5" };
   AtomicInteger idx;
   String currentAlphabet;
   String currentNumeric;
   int currentIndex;
   Dummy dummyObj;

   private ruleSetUp() {

       dummyObj = Mockito.spy(new Dummy());
        // Rule for rs.next()
         Mockito.doAnswer(new Answer<Boolean>() {

        @Override
        public Boolean answer(InvocationOnMock invocation) throws Throwable {
            currentIndex = idx.getAndIncrement();
            if (alphabet.length > currentIndex) {
                currentAlphabet= alphabet[currentIndex];
                currentNumeric= numeric[currentIndex];
                return true;
            } else
                return false;
        };
    }).when(rs).next();

   // Rule for rs.getInt()
   Mockito.doAnswer(new Answer<Integer>() {

        @Override
        public Integer answer(InvocationOnMock invocation) throws Throwable {
            return idx.get() - 1;
        };
    }).when(rs).getInt(2);

    // Rule for rs.getByte()
    Mockito.doAnswer(new Answer<byte[]>() {

        @Override
        public byte[] answer(InvocationOnMock invocation) throws Throwable {
            return currentNumeric.getBytes(StandardCharsets.UTF_8);
        };
    }).when(rs).getBytes(1);

       Mockito.doReturn(currentAplhabet).when(dummyObj).innerMethod(Mockito.anyInt(), Mockito.anyInt());
  }

  @Test
  public void methodTest(){


       ruleSetUp();

  }
}

我正在测试的方法如下:

class Dummy {

       public void method(int param1) {

          /*   some code  */
          param2 = xyz() ;  // Some mathematical calculation
          while(rs.next()) {

              byte[] strByte = rs.getBytes(1); 
              int number = rs.getInt(2);

              String str= new String(strByte, StandardCharset.UTF-8);
              // TEst Case rule causes below value to be always null
              String alphabet = innerMethod(param1, param2);               
          }

       }
}

执行此测试方法时，发现被测试方法中的alphabet值始终为空。根据 currentNumeric 的正确值，正确填充“str”的值。该循环也运行了正确的次数。

我很困惑为什么没有应用innerMethd()的规则。我没有收到任何错误，只是填充的值始终为空，无论循环正在经历哪一次迭代。

你们能指出我错在哪里以及解决方法吗？

谢谢

Answer 1

 String currentAlphabet;

 private ruleSetUp() {
   // [snip]
   Mockito.doReturn(currentAlphabet).when(dummyObj).innerMethod(
       Mockito.anyInt(), Mockito.anyInt());
 }

每次调用 innerMethod 时，Mockito 都会返回 null 因为你告诉它。尽管每次调用 next 时都会设置 currentAlphabet，但在此之前您无需设置任何内容。在调用 ruleSetup 时，currentAlphabet 为 null，因此 Mockito 为每次调用 innerMethod stub null。

您需要使用答案来 stub doReturn，而不是:

doAnswer(new Answer<String>() {
  @Override public void answer(InvocationOnMock invocation) {
    // This field on the test changes based on other invocations.
    return currentAlphabet;
  }
}).when(dummyObj).innerMethod(anyInt(), anyInt());

顺便说一句，由于您要替换多个相关方法的行为，因此为了可读性和易于维护，请考虑使用普通重写:

private DummyObj createDummy() {
  return new DummyObj() {
    private final String[] alphabet= {"a", "b", "c", "d", "e" };
    private final String[] numeric= {"1", "2", "3", "4", "5" };
    AtomicInteger idx;
    String currentAlphabet;
    String currentNumeric;
    int currentIndex;

    @Override public boolean next() { /* ... */ }
    @Override public int nextInt() { /* ... */ }
    @Override public byte nextByte() { /* ... */ }
    @Override public String innerMethod() { /* ... */ }
  };
}