Is it necessary to have Integration Testing Phase?

Since the Integration testing can be done in several levels, I will choose one level as example for this article. The Integration testing that I choose is the software testing for interaction between 2 systems which occurs after System Testing Phase. However, the idea from this article can be applied to other level of Integration Testing Phase as well.


"Is Integration Testing Phase necessary?" This question may be in some testers' mind after they need to do the same testing as System Testing Phase. My answer of this always is "Yes, Of Course". Let see what I have experienced.

I have assigned to do website testing and this website consumes data from various data sources. There are plans to release new version of many data sources on the same date as my website.

I have done my website testing in System Testing Phase and the result looks good. No pending bug from my website testing. Then, I wait until start date of the Integration Testing Phase which every data sources are ready. Shock!!! My website is broken when I do website testing on Integration Testing Phase. What's wrong with my test result from prior website testing?

The issue has been raised to developers for investigation and they take one week to investigate the issue. The problem comes from the new version of one data source. Its version in website testing's report from system test environment is older than integration test.
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From this lesson, I always think about the dependency of my system. Then, manage the risk from them. Finally, do the software testing as soon as possible if the Integration Testing Phase is ready.

Posted in: Software Testing Experience,Software Testing Process