如何使用Powermock模拟常规方法

Question

In groovy I am able to set the desired return value from a method to whatever I want in the test. Can I mock a regular method using PowerMock?

For eg

int getYear() {
    return 2013;
}

In the test can I set something like:

expect(getYear()).andReturn(2012);

//class underTest

class ProxyB {
    public X getDimensions(){
        GetResponseX getResponseX = client.newServiceCall().call().getResponseX();
        int d = getResponseX.getDimensions();
    }
}

I want to mock the part getResponseX.getDimensions() to return 21.

Answer 1

This is the basic code for mocking a simple call. Given the following class:

class Foo{
    int F(){
        return 42;
    }
}

You mock it by:

Foo fooMock = EasyMock.createMock(Foo.class);
EasyMock.expect(fooMock.F()).andReturn(41);

The problem in your case that you need to mock the entire chain of

client.newServiceCall().call().getResponseX()

For this you may need to change the way your class initially obtains a reference to client . EG, get it in a constructor or via a setter method. It might roughly resemble this:

class ProxyB{
    YourClient client;

    ProxyB(YourClient client){
        this.client = client;
    }

    public X getDimensions(){
        GetResponseX getResponseX = client.newServiceCall().call().getResponseX();
        int d = getResponseX.getDimensions();
    }
}

Now, when writing the unit test, you create a mock for YourClient and pass it to the constructor of the class under test. This way you have complete control over what it returns from within the method ProxyB.getDimensions . From this point you mock your way down the call chain (yes, it is a lot of mocks). Eventually, the getResponseX local variable should contain your mock and you can set whatever expectations on it.