如何在TestNG中使用Mockito模拟jdbc连接和resultSet

Question

我必须编写一些单元测试，但我有模拟ResultSet和jdbc Connection的问题。

我有这样的方法：

@Test 
public void test3() throws SQLException, IOException { 

    Connection jdbcConnection = Mockito.mock(Connection.class); 
    ResultSet resultSet = Mockito.mock(ResultSet.class); 

    Mockito.when(resultSet.next()).thenReturn(true).thenReturn(true).thenReturn(true).thenReturn(false); 
    Mockito.when(resultSet.getString(1)).thenReturn("table_r3").thenReturn("table_r1").thenReturn("table_r2"); 
    Mockito.when(jdbcConnection 
      .createStatement() 
      .executeQuery("SELECT name FROM tables")) 
      .thenReturn(resultSet); 

    //when 
    List<String> nameOfTablesList = null; 
    try { 
     nameOfTablesList = Helper.getTablesName(jdbcConnection); 
    } catch (SQLException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 

    //then 
    Assert.assertEquals(nameOfTablesList.size(), 3); 
} 

和错误的显示行executeQuery("SELECT name FROM tables")这听起来像这样：

java.lang.NullPointerException HelperTest.test3(HelperTest.java:71) 

任何想法什么问题呢？

Answer 1

您需要在jdbcConnection.createStatement()上创建期望。

默认情况下，我相信会返回一个null。

应改为类似：

ResultSet resultSet = Mockito.mock(ResultSet.class); 
Mockito.when(resultSet.next()).thenReturn(true).thenReturn(true).thenReturn(true).thenReturn(false); 
Mockito.when(resultSet.getString(1)).thenReturn("table_r3").thenReturn("table_r1").thenReturn("table_r2"); 

Statement statement = Mockito.mock(Statement.class); 
Mockito.when(statement.executeQuery("SELECT name FROM tables")).thenReturn(resultSet); 

Connection jdbcConnection = Mockito.mock(Connection.class); 
Mockito.when(jdbcConnection.createStatement()).thenReturn(statement);