Checking test coverage

A test coverage report shows which lines of source code were covered by tests.

How to do it...

1. To get a quick coverage result, run tests with the cover flag:

   $ go test -cover
   PASS
   coverage: 76.2% of statements

2. To write a test coverage profile to a separate file so you can get detailed reports on it, give the test run a cover profile file name:

   $ go test -coverprofile=cover.out
   PASS
   coverage: 76.2% of statements

   Then, you can see the coverage report in your browser using:

   $ go tool cover -html=cover.out

   This command opens the browser and allows you to see which lines were covered by tests.