When using TextMate2 with the cucumber bundle, it does not recognize step definitions (e.g. custom_steps.rb) as such but believes they are plain Ruby files. But there is help!

Solution

Add these lines to the bottom of your .tm_properties file (in ~/ for global settings, in any directory for per-project settings):

[ "*_steps.rb" ]
fileType = "source.ruby.rspec.cucumber.steps"

Apparently, this works for any files. Define a regex and specify custom settings. The attached article lists all available configuration options (which are many).