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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?

rolve
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Manav
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  • You are trying to unit your component then you should mock others. Unit test on single component should not dependant on other componenets, I believe. – Bhesh Gurung Oct 19 '12 at 15:53
  • There are **books** on unit testing. There is no absolute truth or standard when it comes to unit testing. There are best practices and there are times when it's convenient to do things differently. – madth3 Oct 19 '12 at 16:01

4 Answers4

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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.

rolve
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    Could you please suggest some Mock Web Service clients creation tutorial. Thanks. – Hemanth Oct 24 '12 at 16:04
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    I'm sorry, but I don't know any tutorial specifically for web service mocking. But if your code is well designed, you should have a (Java) interface for the third party service so that you can easily replace the actual implementation with a mock. – rolve Oct 24 '12 at 17:34
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    Ya it would be real fun if there were some predefined guidelines... I came across this article about unit testing webservices and it says that it is ok to go over the wire... http://www.drdobbs.com/web-development/unit-testing-web-services/211201695... also microsoft also recomends going to the server... http://msdn.microsoft.com/en-us/library/ms243399%28v=vs.80%29.aspx – Manav Oct 25 '12 at 04:57
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This depend on what you're unit-testing.

So if you're testing out whether you can successfully communicate with the third-party webservice, you wouldn't obviously try to mock this. However if you're unit-testing some business use-cases that are part of your web-service offering (unrelated to what the other modules/web services are doing), then you might want to mock the third-party web service.

Sujay
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You should test both but both test cases does not fall under Unit testing.

Unit testing is primarily used for testing individual smaller pieces i.e. classes and methods. Unit testing is something that should preferably happen during the build process without any human intervention. So as part of Unit testing you should mock out the third party webservice. The advantage of mocking is that you can make the mocked object behave in many possible ways and test your classes/methods to make sure they handle all possible cases.

When multiple systems are involved, the test case falls under System/Integration/Functional testing. So as part of your System/Integration/Functional testing, you should call the methods in other webservice from your webservice and make sure everything works as expected.

Hitesh
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Mocking is an usually essential in unit testing components which have dependent components. This is so because in unit testing , you are limited to testing that your code works correctly ( does what its contract says it will do ). If this method , in trying to do the part of its contract depends upon other component doing their part correctly , it is perfectly fine to mock that part out ( assuming that they work correctly ).

If you dont mock the other dependent parts , you soon run into problems. First , you cannot be certain what behavior is exhibited by that component. Second , you cannot predict the results of your own test ( because you dont know what was the inputs supplied to your tests )

Bhaskar
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