You can't use Simplecov from within Rake::TestTask
since that task runs the tests in a separate process. See https://github.com/colszowka/simplecov/issues/88.
EDIT
To clarify: You can certainly use SimpleCov by using a Rakefile, but you can't start (SimpleCov.start
) it in the Rakefile. You need to do that in the test, e.g. in your test helper.
Keep in mind that SimpleCov.start
must be called before requiring your production code.