Kevin Robinson kevinrobinson

Hello!

This is a commentary and discussion from walking through what happens on startup in [https://github.com/circleci/frontend], looking at this SHA in December 2014: [https://github.com/circleci/frontend/commit/273558250040ce197e44e683d5528381f36c4eea].

The first part is a literal walkthrough, where I'm tracing my reading of how the code works. This is a way to check my understanding, since of course I don't have all of your context. And it's also a way to echo back to you how someone else might experience this code without that context. The second part is about asking questions, making suggestions, and exploring some paths for making it even more awesome. I also mixed in a few asides in the walkthrough part where I jump ahead a bit.

Doing this with colleagues has worked well for me as a way to do in-depth code reviews about more abstract design and architectural questions. The goal of the the first part is to clarify we're all looking at the same thing, which creates the space and shared understa

	...

	# Create a folder, and only copy the Gemfile and Gemfile.lock
	RUN mkdir /mnt/somerville-teacher-tool
	COPY Gemfile /mnt/somerville-teacher-tool/Gemfile
	COPY Gemfile.lock /mnt/somerville-teacher-tool/Gemfile.lock

	# Now run bundle install. This step will only be invalidated
	# if the Gemfile or Gemfile.lock changes.
	RUN bundle install

	# This is based off https://docs.docker.com/compose/rails/
	rails:
	build: .
	volumes:
	- .:/mnt/somerville-teacher-tool
	working_dir: /mnt/somerville-teacher-tool
	environment:
	DATABASE_URL: postgresql://postgres@postgres # overrides hostname and username
	ports:
	- "3000:3000"

	describe "setup", =>
	@val = 0
	beforeEach => @val += 10
	afterEach => @val -= 100

	describe "when loaded", =>
	it "a", => expect(this.val).toEqual 10
	it "b", => expect(this.val).toEqual 10
	it "c", => expect(this.val).toEqual 10