Mockito 上的空指针 [英] Nullpointer on Mockito when

问题描述

我使用以下测试来测试我的实用程序类，我使用 mockito 进行 sql 连接.

I use following test to test my utitiliesclass, I use mockito for the sql connection.

    @Mock
    public Connection connectionMock;

    @Before
    public void setUp(){
        MockitoAnnotations.initMocks(this);
    }    
@Test
    public void testResource(){
        String sql = Utilities.resourceToString("testSql.sql");
        try {
            Mockito.when(connectionMock.createStatement().executeQuery(sql)).thenAnswer(new Answer<String>() {
                @Override
                public String answer(InvocationOnMock invocationOnMock) throws Throwable {
                    return "X";
                }
            });

我在 Mockito.when 线上得到一个空指针，怎么了?

I get a nullpointer on the line Mockito.when, what is wrong?

推荐答案

你需要另一个模拟...

You need another mock...

connectionMock.createStatement()

...将返回 null，除非您为其设置期望值.

...will return null unless you set up an expectation for it.

例如添加...

@Mock
private Statement statement;

...

when(connectionMock.createStatement()).thenReturn(statement);
when(statement.executeQuery(sql)).thenAnswer(...);

更新

要回答下面的评论，您应该返回结果集，而不是字符串.例如...

Update

To answer the comment below, you should be returning a result set, not a string. For example...

@Mock
private ResultSet resultSet;

...

when(statement.executeQuery(sql)).thenReturn(resultSet);
when(resultSet.getString(1)).thenReturn("X");

... call the class under the test...

// Add verification that "next" was called before "getString"...
// (not 100% necessary, but makes it a more thorough test)
InOrder order = inOrder(resultSet);
order.verify(resultSet).next();
order.verify(resultSet).getString(1);

更新 #2

删除错误的内容

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