Java - 用于多个测试的模拟私有(private)静态构造函数

Question

我是java测试的新手，现在已经摆弄了一会儿，但没有运气，我有以下类(class):

public class Bar {
    public Object doSomething(int a, String b){
        return "something";
    }

    public Object doSomethingElse(int a, int b, String c){
        return "something else";
    }
}

public class Foo {
    private static Bar bar = new Bar();

    public static void start(int a, int b, String c){
        if(a == 1) { // some calculated condition
            bar.doSomething(a, c);
        } else {
            bar.doSomethingElse(a, b, c);
        }
    }
}

@RunWith(PowerMockRunner.class)
@PrepareForTest(Foo.class)
public class FooTest {
    @Test
    public void somethingTest() throws Exception {
        Bar barMock = createMock(Bar.class);

        expectNew(Bar.class).andReturn(barMock);

        expect(barMock.doSomething(1, "xxx")).andReturn("ABC");

        replay(barMock, Bar.class);

        Foo.start(1, 2, "xxx");
        verify(barMock, Bar.class);
    }

    @Test
    public void somethingElseTest() throws Exception {
        Bar barMock = createMock(Bar.class);

        expectNew(Bar.class).andReturn(barMock);

        expect(barMock.doSomethingElse(0, 2,"xxx")).andReturn("ABC");

        replay(barMock, Bar.class);

        Foo.start(0, 2, "xxx");
        verify(barMock, Bar.class);
    }
}

单独运行测试可以，但不能运行整个类(class)，我认为这与:

 private static Bar bar = new Bar();

但我不是 100% 确定。不管怎样，假设我无法更改 foo/bar 类，我该如何解决这个问题？

Answer 1

我会将 Foo 重构为:

public class Foo {
    private static Bar bar = new Bar();

    public static void start(int a, int b, String c){
        if(a == 1) { // some calculated condition
            doSomething(a, c);
        } else {
            doSomethingElse(a, b, c);
        }
    }

    private static void doSomething(int a, String c) {
        bar.doSomething(a, c);
    }

    private static void doSomethingElse(int a, int b, String c) {
        bar.doSomethingElse(a, b, c);
    }
}

并像这样测试 Foo:

import static org.mockito.Matchers.eq;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.AdditionalMatchers;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;


@RunWith(PowerMockRunner.class)
@PrepareForTest({Foo.class})
public class FooTest {

    @Before
    public void setup() throws Exception {
        PowerMockito.spy(Foo.class);
    }


    @Test
    public void somethingTest() throws Exception {
        Foo.start(1, 2, "xxx");   
        PowerMockito.verifyPrivate(Foo.class).invoke("doSomething", eq(1), eq("xxx"));
    }

    @Test
    public void somethingElseTest() throws Exception {
        Foo.start(0, 2, "xxx"); 
        PowerMockito.verifyPrivate(Foo.class).invoke("doSomethingElse", AdditionalMatchers.not(eq(1)), eq(2), eq("xxx"));
    }
}

并单独测试 Bar，这可以简单地使用 Mockito 完成。