测试（模拟）一个无效函数，它在内部调用其他与数据库建立连接的函数

Question

我有一个class，其中有一个私有变量Connection。我想测试 functionA，为此我必须模拟 functionB 和 functionC。

我尝试使用 powermock 和 mockito 但无法做到。

测试 fucntionA 和模拟 functionB 和 functionC 应该做什么。

public class ToMock {

    private Connection connection;

    private static functionA(String name) {       
        // do something    
        functionB()    
        return xyz;
    }

    public static void functionB() {
         connection = functionC("localhost", 10000);    
    }

    public static void functionC(String hostName, int port) {
        //make a connection to db

        String connectionString = String.format("jdbc:hive2://%s:%d/",emrHost, port);

        LOGGER.info("Connection string {}", connectionString);

        try {

            Class.forName("org.apache.hive.jdbc.HiveDriver");    
            Connection con = DriverManager.getConnection(connectionString, "hadoop", "");

            LOGGER.info("Connected successfully");

            return con;    
        } catch (ClassNotFoundException e) {
            throw Throwables.propagate(e);
        }
    }
}

Answer 1

嗯，你有 static 方法。所以你不能按其设计使用 Mockito。你可以使用 PowerMock。请参阅此处的用法：Link.

看这里：link.

基本上代码如下所示（从 PowerMock 示例复制），

@RunWith(PowerMockRunner.class)
@PrepareForTest(Static.class)
public class YourTestCase {
@Test
public void testMethodThatCallsStaticMethod() {
    // mock all the static methods in a class called "Static"
    PowerMockito.mockStatic(Static.class);
    // use Mockito to set up your expectation
    Mockito.when(Static.firstStaticMethod(param)).thenReturn(value);
    Mockito.when(Static.secondStaticMethod()).thenReturn(123);

    // execute your test
    classCallStaticMethodObj.execute();

    // Different from Mockito, always use PowerMockito.verifyStatic() first
    // to start verifying behavior
    PowerMockito.verifyStatic(Mockito.times(2));
    // IMPORTANT:  Call the static method you want to verify
    Static.firstStaticMethod(param);


    // IMPORTANT: You need to call verifyStatic() per method verification, 
    // so call verifyStatic() again
    PowerMockito.verifyStatic(); // default times is once
    // Again call the static method which is being verified 
    Static.secondStaticMethod();

    // Again, remember to call verifyStatic()
    PowerMockito.verifyStatic(Mockito.never());
    // And again call the static method. 
    Static.thirdStaticMethod();
}
}

这里Static是静态方法所属的class

Answer 2

像@neurotic-d 描述的那样重构你的代码。像这样：

public class ToMock {

    private Connection connection;

    public ToMock(Connection connection){
        this.connection = connection;
    }

    private functionA(String name) {       
        // do something    

        return xyz;
    }
}  



public class ToMockFactory {

    public static ToMock toMock(){
        return new ToMock(functionB());
    }

    public static Connection functionB() {
        return functionC("localhost", 10000);    
    }

    public static Connection functionC(String hostName, int port) {
        //make a connection to db

        String connectionString =     String.format("jdbc:hive2://%s:%d/",emrHost, port);

        LOGGER.info("Connection string {}", connectionString);

        try {

            Class.forName("org.apache.hive.jdbc.HiveDriver");    
            Connection con = DriverManager.getConnection(connectionString,   "hadoop", "");

            LOGGER.info("Connected successfully");

            return con;    
        } catch (ClassNotFoundException e) {
            throw Throwables.propagate(e);
        }
    }
}

测试（模拟）一个无效函数，它在内部调用其他与数据库建立连接的函数

Test(Mocking) a void function which internally calls other functions that create connection with database

java

unit-testing

mocking

mockito

powermockito