jMockit-如何使构造函数调用返回模拟

Question

我们目前使用Mockito+PowerMock作为我们的主要模仿框架，并且在开始将一些代码转移到Java8时遇到了一些问题。因此，我们决定将jMockit作为一种替代方案进行评估。我对嘲笑概念有相当好的理解，但我承认我对jMockit的经验非常有限。

然而，我在测试一些在我看来应该是非常基本的东西时遇到了问题：被测试的类在其构造函数中使用New创建其他类的实例。我想让这个新调用返回一个模拟实例。

import mockit.Expectations;
import mockit.Injectable;
import mockit.Mocked;
import org.testng.annotations.Test;

public class ClassUnderTestTest {
    interface SomeService {
        void doWork();
    }

    class ClassUnderTest {
        private final SomeService service;

        public ClassUnderTest() {
            this.service = new SomeService() {
                @Override
                public void doWork() {
                }
            };
        }
    }

    @Injectable
    private SomeService mockService;

    @Test
    public void shouldBeAbleToMaskVariousNumbers() throws Exception {
        new Expectations() {{
            new ClassUnderTest();
            result = mockService;
        }};
    }
}

java.lang.IllegalStateException: Missing invocation to mocked type at this point;
please make sure such invocations appear only after the declaration of a suitable
mock field or parameter

Answer 1

使用jMockit很容易做到这一点：

public class ClassUnderTestTest {
    interface SomeService { int doWork(); }

    class ClassUnderTest {
        private final SomeService service;

        ClassUnderTest() {
            service = new SomeService() {
                @Override public int doWork() { return -1; }
            };
        }

        int useTheService() { return service.doWork(); }
    }

    // This annotation is a variation on @Mocked, which extends
    // mocking to any implementation classes or subclasses of
    // the mocked base type.
    @Capturing SomeService mockService;

    @Test
    public void shouldBeAbleToMaskVariousNumbers() {
        new Expectations() {{ mockService.doWork(); result = 123; }};

        int n = new ClassUnderTest().useTheService();

        assertEquals(123, n);
    }
}