Required files
spec/runner/formatter/base_formatter
spec/runner/formatter/base_text_formatter
spec/runner/formatter/progress_bar_formatter
spec/runner/formatter/rdoc_formatter
spec/runner/formatter/specdoc_formatter
spec/runner/formatter/html_formatter
spec/runner/formatter/failing_examples_formatter
spec/runner/formatter/failing_behaviours_formatter
spec/runner/formatter/snippet_extractor