Project is Rails 5.x with rspec.

When configuring simplecov via spec/rails_helper.rb like this:

require 'simplecov'
SimpleCov.start 'rails'

running rake results in the expected behavior of simplecov generating a report once.

If I change the rails_helper.rb config to just:

require 'simplecov'

And use a .simplecov config file like this:

SimpleCov.start 'rails'

The coverage report is generated twice. The first report is as expected, but then gets overwritten by the second report, which displays 0% coverage for all classes.

If I just run rspec instead of rake, then only one genuine coverage report is generated.