Watchr is teh awesome

Autotest spoiled me for immediate feedback during the development cycle. So as I was going through the Relevance functional koans for Clojure, I had a little Watchr script continually re-running the tests from the exercise at every file save. This is what that script looked like:

	def run_it
	system('sh run.sh')
	end
	run_it
	watch( 'src/koans/.*\.clj' ) { run_it }

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There's barely anything there. All it does is run the "run.sh" script that comes with the koans whenever a ".clj" file in anywhere under the "src/koans" directory is saved. It's just a simple little thing, but so very useful.

I later discovered a fork of those koans (from David Laing) that adds JavaScript lessons. So I adapted my watchr script to start the KoansRunner file in Safari, reload the test page, and scroll to the bottom on every save of the JavaScript files.

	def js_command(command)
	"-e 'do JavaScript \"#{command}\" in first document'"
	end
	def reload
	js_command("window.location.reload();")
	end
	def scroll
	js_command("window.scrollTo(0, document.body.scrollHeight);")
	end
	def safari_cmd(*cmds)
	"osascript -e 'tell app \"Safari\"' #{cmds.join(' ')} -e 'end tell'"
	end
	def reload_and_scroll
	safari_cmd reload, scroll
	end
	def scroll_to_bottom
	safari_cmd scroll
	end
	def run_it(command = scroll_to_bottom)
	system("ps -xc|grep -sq Safari && #{command}")
	end
	system("open /Applications/Safari.app KoansRunner.html")
	run_it
	watch( 'koans/.*\.js' ) { run_it(reload_and_scroll) }

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I can't say enough about the value of rapid feedback from automated tests during the learning/development cycle. The absence of context switching to manually rerun the tests is great WIN.