如何测试包含void方法的Void方法？

Question

I am using PowerMockito. I would like to test the following code.

class Foo{
    void outerVoid(){
        innerVoid(); // method of another class
    }
}

How can I test OuterVoid() without invoking the innerVoid()?

The innerVoid() contains database related objects so it should not be called, or it will become an integration test.

Answer 1

Start by refactoring your code if possible.

Create an interface Bar .

interface Bar {
    void innerVoid();
}

Now use the design pattern Dependency Injection to inject an implementation of this interface with the innerVoid() method into your Foo class.

class Foo {
    Bar bar;

    Bar getBar() {
        return this.bar;
    }

    void setBar(Bar bar) {
        this.bar = bar;
    }

    void outerVoid() {
        this.bar.innerVoid();
    }
}

Now you can mock the Bar class all you want.

Bar mockBar = createMockBar(...); // create a mock implementation of Bar
Foo foo = new Foo();
foo.setBar(mockBar);
... continue testing ...