IntelliJ show changed lines not covered by unit tests

Question

In my daily work, I intend to write tests for the code that I change.

My workflow usually is like this:

• Find code to change
• Write failing test
• Change code
• Watch test pass

And before commit, I run all tests.

But in reality, I could change any lines unknowingly about our test coverage.

What I do now is usually to see if the CI server will show increasing test coverage. But this is a manual task which I have to do after my commit, and it also may be cluttered by others committing code.

How can IntelliJ help me? I cannot directly find a way to compare test coverage. How can I ensure my changes drive test coverage up?

How do you currently handle this aspect of your code coverage?

Answer 1

IntelliJ IDEA includes the code coverage support since the 6.0 version (Ultimate edition).

Through Run -> Edit Configurations -> Code Coverage you can configure the code coverage you want, then you can issue the "Run tests with coverage" command. You'll have as a result some code coverage data on the project view. When you open a source file you can also see what lines are fully covered, partially covered, or not covered at all.

You might want to customize the Colors & Fonts through File -> Settings -> Editor -> Colors & Fonts -> General modifying the following entries:

• Full line coverage
• Partial line coverage
• Uncovered line

For example I wanted to add more evidency to the coverage, so I configured a different background for those lines.

Once you have some red lines (not covered), you can try to cover them and if you see them becoming green it means you did a good job, and so on!