feat: Add testing principles #319

	name: Main

	on:
	push:
	branches: [main]
	pull_request:

	jobs:
	check-workflows:
	name: Check workflows
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v3
	- name: Download actionlint
	id: download-actionlint
	run: bash <(curl https://raw.githubusercontent.com/rhysd/actionlint/7fdc9630cc360ea1a469eed64ac6d78caeda1234/scripts/download-actionlint.bash) 1.6.23
	shell: bash
	- name: Check workflow files
	run: ${{ steps.download-actionlint.outputs.executable }} -color
	shell: bash

	lint:
	name: Lint
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v3
	- name: Use Node.js
	uses: actions/setup-node@v3
	with:
	node-version-file: '.nvmrc'
	cache: 'yarn'
	- name: Install Yarn dependencies
	run: yarn --immutable
	- run: yarn lint
	- name: Require clean working directory
	shell: bash
	run: \|
	if ! git diff --exit-code; then
	echo "Working tree dirty at end of job"
	exit 1
	fi

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