This is the second of a two-post series in which we try to understand how code coverage is measured and reported in JavaScript by building a simple code coverage tool ourselves. You can find the first post here and the reference code for this exercise here.
By the end of the last post, we had built an instrumenter. It takes our single-file source program and modifies it to add counters. These counters let us measure statement coverage when our tests run. The next step is to make our tests use our instrumented source code.