Question

I have a web service which calls a third party web service.

Now I want to unit-test my web service. For this, should I mock the third party web service or is it fine to call it during the tests?

Is there any standard document on unit testing?

Answer 1

Yes, you should mock the third party web service for unit testing. Here are some advantages:

1. Your unit tests are independent of other components and really only test the unit and not also the web service. If you include the service in your unit tests and they fail, you won’t know whether the problem is in your code or in the foreign web service.

2. Your tests are independent of the environment. If the Internet connection is ever down or you want to test on a machine that doesn’t have Internet access at all, your test will still work.

3. Your tests will be much faster without actually connecting to the web service. This might not seem like a big thing but if you have many many tests (which you should), it can really get annoying.

4. You can also test the robustness of your unit by having the mock send unexpected things. This can always happen in the real world and if it does, your web service should react nicely and not just crash. There is no way to test that when using the real web service.

However, there is also integration testing. There, you test the complete setup, with all components put together (integrated). This is where you would use the real web service instead of the mock.

Both kinds of testing are important, but unit testing is typically done earlier and more frequently. It can (and should) be done before all components of the system are created. Integration testing requires a minimal amount of progress in all of most of the components.