The importance of writing unit tests have been heavily discussed. However, reality is cruel. Many developers do not write UT, and even larger amount of developers write funny tests just to pass the code coverage bar, and some developers with ambition are not quite sure about how to write good unit tests. Most good UT are written by top developers.
I thought I am that kind of ambitious developer, so I spend two weekends to start to learn it. Most cases listed below are originated from or revised from the book “Practical Unit Testing with Testng and Mockito” by Tomek Kaczanowski. A really good book worth reading.
Before we start, let’s visit the concepts of SUT and DOC.