java - 如何使用mockito测试匿名类中的方法调用

Question

1.这是我的代码，我想使用 mock 或 powermockito 对其进行单元测试:

public class CarrierGroupDAO {
    @Autowired
    protected JdbcTemplate jdbcTemplate;

    public CarrierGroupDAO() {  }

    public Map<Long, String> getAllCarrierGroups() {
        String sql = "select t.carrier_group_id, t.updated_by from  pv_carrier_group t where t.status = 'Q'";
        return jdbcTemplate.execute(sql, new CallableStatementCallback<Map<Long, String>>() {
            @Override
            public Map<Long, String> doInCallableStatement(CallableStatement cs)
                    throws SQLException, DataAccessException {
                ResultSet resultSet = cs.executeQuery();
                Map<Long, String> carrierGroups = new HashMap<>();
                while (resultSet.next()) {
                    carrierGroups.put(resultSet.getLong("carrier_group_id"), resultSet.getString("updated_by"));
                }
                return carrierGroups;
            }
        });
    }
}

2.按照我的测试代码:

    @Test
    public void testGetAllCarrierGroups() {
        CarrierGroupDAO carrierGroupDAO=new CarrierGroupDAO();

        CallableStatement cs=PowerMockito.mock(CallableStatement.class);
        JdbcTemplate jdbcTemplate=PowerMockito.mock(JdbcTemplate.class);
        PowerMockito.mock(JdbcTemplate.class);
        PowerMockito.when(jdbcTemplate.execute(Mockito.any(String.class),Mockito.any(CallableStatementCallback.class))).thenAnswer(new Answer<Object>() {
            @Override
            public Object answer(InvocationOnMock invocation) throws Throwable {
                Object[] args=invocation.getArguments();
                System.out.println(args.length);
                TransactionCallback arg = (TransactionCallback)args[1];
                return ((CallableStatementCallback) arg).doInCallableStatement(cs);
            }
        });

        ResultSet resultSet =PowerMockito.mock(ResultSet.class);
        try {
            PowerMockito.when(cs.executeQuery()).thenReturn(resultSet);
            PowerMockito.when(resultSet.next()).thenReturn(true).thenReturn(false);
            PowerMockito.when(resultSet.getLong(Mockito.any(String.class))).thenReturn((long)1);
            PowerMockito.when(resultSet.getString(Mockito.any(String.class))).thenReturn("haha");
            carrierGroupDAO.getAllCarrierGroups();
            Mockito.verify(cs).executeQuery();
        } catch (SQLException e) {
            e.printStackTrace();
        }       
    }

错误信息:

    java.lang.NullPointerException
    at CarrierGroupDAO.getAllCarrierGroups(CarrierGroupDAO.java:27)
    at CarrierGroupDAOTest.testGetAllCarrierGroups(CarrierGroupDAOTest.java:47)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

如果您有任何想法解决这个问题，请询问我，深深感谢您!

Answer 1

这里有几个问题:

1. 您正在模拟 JdbcTemplate，但您没有将此模拟实例注入(inject)到 CarrierGroupDAO 中(这会导致 NullPointerException)。
2. 您正在使用 PowerMockito，其中 Mockito 就足够了。
3. 您的 Answer 尝试将 jdbcTemplate.execute(...) 的 secopnd 参数转换为 TransactionCallback。

可以通过以下方式轻松修复它们:

• 将 JdbcTemplate 注入(inject) CarrierGroupDAO

  public class CarrierGroupDAO {
  
      private JdbcTemplate jdbcTemplate;
  
      @Autowired
      public CarrierGroupDAO(JdbcTemplate jdbcTemplate) {
          this.jdbcTemplate = jdbcTemplate;
      }
  
      public Map<Long, String> getAllCarrierGroups() {
          String sql = "select t.carrier_group_id, t.updated_by from  pv_carrier_group t where t.status = 'Q'";
          return jdbcTemplate.execute(sql, new CallableStatementCallback<Map<Long, String>>() {
              @Override
              public Map<Long, String> doInCallableStatement(CallableStatement cs)
                      throws SQLException, DataAccessException {
                  ResultSet resultSet = cs.executeQuery();
                  Map<Long, String> carrierGroups = new HashMap<>();
                  while (resultSet.next()) {
                      carrierGroups.put(resultSet.getLong("carrier_group_id"), resultSet.getString("updated_by"));
                  }
                  return carrierGroups;
              }
          });
      }
  }
  

• 重新设计测试用例以使用 Mockito 并更改 Answer 实现:

  @Test
  public void testGetAllCarrierGroups() throws SQLException {
      JdbcTemplate jdbcTemplate = Mockito.mock(JdbcTemplate.class);
      CarrierGroupDAO carrierGroupDAO = new CarrierGroupDAO(jdbcTemplate);
  
      CallableStatement cs = Mockito.mock(CallableStatement.class);
      Mockito.when(jdbcTemplate.execute(Mockito.any(String.class), Mockito.any(CallableStatementCallback.class)))
              .thenAnswer(new Answer<Object>() {
                  @Override
                  public Object answer(InvocationOnMock invocation) throws Throwable {
                      Object[] args = invocation.getArguments();
                      System.out.println(args.length);
                      CallableStatementCallback arg = (CallableStatementCallback) args[1];
                      return arg.doInCallableStatement(cs);
                  }
              });
  
      ResultSet resultSet = Mockito.mock(ResultSet.class);
      Mockito.when(cs.executeQuery()).thenReturn(resultSet);
      // expecting one entry in the resultset
      Mockito.when(resultSet.next()).thenReturn(true).thenReturn(false);
      long expectedKey = 1;
      String expectedValue = "haha";
      Mockito.when(resultSet.getLong(Mockito.any(String.class))).thenReturn(expectedKey);
      Mockito.when(resultSet.getString(Mockito.any(String.class))).thenReturn(expectedValue);
  
      Map<Long, String> allCarrierGroups = carrierGroupDAO.getAllCarrierGroups();
      Assert.assertEquals(1, allCarrierGroups.size());
      Assert.assertTrue(allCarrierGroups.containsKey(expectedKey));
      Assert.assertEquals(expectedValue, allCarrierGroups.get(expectedKey));
  }