Silence the simplecov output message

It's very rare for the information in this message to be useful or
actionable when running the tests, so it's best to silence the message.

test/test_helper.rb

@@ -1,6 +1,15 @@
 require "coveralls"
 Coveralls.wear!("rails")
 
+# Override the simplecov output message, since it is mostly unwanted noise
+module SimpleCov
+  module Formatter
+    class HTMLFormatter
+      def output_message(_result); end
+    end
+  end
+end
+
 # Output both the local simplecov html and the coveralls report
 SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter.new(
   [SimpleCov::Formatter::HTMLFormatter,