 
     * `:test_pattern` - a pattern to load test files, defaults to `*_test.exs`.
 
+    * `:warn_test_pattern` - a pattern to match potentially missed test files 
+      and display a warning, defaults to `*_test.ex`.
+
     * `:test_coverage` - a set of options to be passed down to the coverage
       mechanism.
 

        System.at_exit fn _ ->
          if failures > 0, do: exit({:shutdown, 1})
        end
    end
  end


    # Finally parse, require and load the files
    test_files   = parse_files(files, test_paths)
    test_pattern = project[:test_pattern] || "*_test.exs"
    warn_test_pattern = project[:warn_test_pattern] || "*_test.ex"

    matched_test_files = Mix.Utils.extract_files(test_files, test_pattern)
    matched_warn_test_files = 
      Mix.Utils.extract_files(test_files, warn_test_pattern) -- matched_test_files
    
    display_warn_test_pattern(matched_warn_test_files, test_pattern)
    
    case matched_test_files do
      [] ->
        Mix.shell.error "Test patterns did not match any file: " <> Enum.join(files, ", ")
      test_files ->
