Add CodeCov for Ruby coverage reports (#23868)

spec/spec_helper.rb

@@ -2,13 +2,21 @@
 
 if ENV['DISABLE_SIMPLECOV'] != 'true'
   require 'simplecov'
+  require 'simplecov-lcov'
+  SimpleCov::Formatter::LcovFormatter.config.report_with_single_file = true
+  SimpleCov.formatter = SimpleCov::Formatter::LcovFormatter
   SimpleCov.start 'rails' do
+    enable_coverage :branch
+    enable_coverage_for_eval
+
     add_filter 'lib/linter'
     add_group 'Policies', 'app/policies'
     add_group 'Presenters', 'app/presenters'
     add_group 'Serializers', 'app/serializers'
     add_group 'Services', 'app/services'
     add_group 'Validators', 'app/validators'
+
+    add_group 'Libraries', 'lib'
   end
 end