Perhaps Android's Achilles' heel would be the lack of documentation, and the number of places you have to visit to get the complete version of what you are trying to find, or what's even worse, in many cases the official documentation is incorrect, or has not been updated to match the current release. The documentation for the new Gradle build system is very sparse on the ground, and this is where most people start when trying to read up on code coverage; so let's light up a few dark corners.

Code coverage is a measure used in software testing that describes the amount of source code that was actually tested by the test suite, and to what degree, following some criteria. As code coverage inspects the code directly, it is therefore a form of white box testing.