Allow single tests to be passed in rake test task

Rakefile

@@ -12,9 +12,21 @@ else
     t.libs << "test"
     t.libs << "lib"
 
+    # Running specific tests with line numbers, like with rails test, is not supported by default in rake.
+    # By setting the TESTOPS env var we can however specify the name of a single test with underscores instead of spaces.
+    # So run your single test by calling for ex:
+    #
+    # rake test /Users/sebastian/projects/cheddar/rails-twirp/test/ping_controller_test.rb "uncaught errors should bubble up to the test"
+
     file_name = ARGV[1]
+    test_name = ARGV[2]&.tr(" ", "_")
+
+    ENV["TESTOPTS"] = "--verbose"
 
     t.test_files = if file_name
+      if test_name
+        ENV["TESTOPTS"] = ENV["TESTOPTS"] + " --name=#{test_name}"
+      end
       [file_name]
     else
       FileList["test/**/*_test.rb"]