use nicer env var

.github/workflows/ci.yml

@@ -62,7 +62,7 @@ jobs:
         bundle update
         bundle exec rake
       env:
-        CI: true
+        MEASURE_COVERAGE: true
         RAILS_VERSION: ${{ matrix.rails_version }}
     - name: Upload coverage results
       uses: actions/upload-artifact@master

test/test_helper.rb

@@ -2,7 +2,7 @@
 require "simplecov"
 require "simplecov-console"
 
-if ENV["CI"]
+if ENV["MEASURE_COVERAGE"]
   SimpleCov.start do
     command_name "rails#{ENV["RAILS_VERSION"]}-ruby#{ENV["RUBY_VERSION"]}" if ENV["RUBY_VERSION"]