Testing Tricks #1: Dealing with "new"

As I continue my efforts to get my Android applications under unit and integration tests, I have come across a few tips/tricks to successfully deal with troublesome code. So I decided to start a new blog post series, "Testing Tricks". I will try to post a new trick each week. So let's get started...


Problem Code

So I wanted to test this code:

public void readDeepLink(String path) {
    new DeepLinkReader().readDeepLink(path);
}

Just wanted to make sure the readDeepLink method was being called. The troublesome part is that I didn't want to create a actual DeepLinkReader because the real readDeepLink method made calls to the network. So what's the fix?


Solution


Wrap the call to the "new" creation in a separate method. That way I could override the newly created method with a mock. This would avoid creating a real DeepLinkReader object and would allow me to use Mockito to verify the mock's interactions.

Fixed Code


// in the MainPresenter.java
public void readDeepLink(String path) {
    getDeepLinkReader().readDeepLink(path);
}

DeepLinkReader getDeepLinkReader() {
    return new DeepLinkReader(currentData, events);
}

// in the MainPresenterTest.java
@Mock private DeepLinkReader deepLinkReader;

@Test
public void shouldReadDeepLink() throws Exception {
    MainPresenter mainPresenter = new MainPresenter() {

        DeepLinkReader getDeepLinkReader() {
            return deepLinkReader;
        }
    };

    mainPresenter.readDeepLink("washingtonpost.com");

    verify(deepLinkReader).readDeepLink("washingtonpost.com");
}
Hope you found this useful, until next time!