Add code coverage reporting

https://artsyproduct.atlassian.net/browse/PLATFORM-1136

Problem:

One part of the product health matrix story [spike][spike] is code
coverage for each service. However, there is no pattern at Artsy for
measuring code coverage for Javascript applications.

While there are existing tools out there for tracking and reporting code
coverage, such as [istanbul.js][istanbul-js], [coveralls][coveralls],
and [codecov][codecov], the complexities:

1. A multi-runner test suite (jest and mocha), and
2. A Circle CI -> Docker -> Docker test runtime

have resulted in a tough problem to solution around.

Solution:

After spending a lot of time trying to get Coveralls instrumentation to
work, we pivoted to using Codecov. At a high level, this commit does the
following:

1. Updates our calls to `jest` and `mocha` to write code coverage
information to a `.nyc_output` directory (default for nyc/istanbul)

2. Manipulates the `jest` coverage information to be compatible with
`mocha` coverage information via a JS script. See [motivating GH
issue][gh-issue].

3. Merges the `jest` and `mocha` coverage information together using the
`nyc` CLI

4. Introduces a bash executable provided by codecov to instrument the
merged information to codecov

Co-authored-by: Kieran Gillen <[email protected]>

[spike]:https://artsyproduct.atlassian.net/browse/PLATFORM-1098
[istanbul-js]:https://github.com/istanbuljs/nyc
[coveralls]:https://coveralls.io/
[codecov]:https://codecov.io/gh/artsy/positron/
[gh-issue]:jestjs/jest#2418

Author: dleve123

.circleci/config.yml

@@ -9,7 +9,7 @@ jobs:
       - setup_remote_docker
       - run:
           name: Test
-          command: COMMIT_HASH=$(git rev-parse --short HEAD) hokusai test --build
+          command: COMMIT_HASH=$(git rev-parse HEAD) CODECOV_TOKEN=$CODECOV_TOKEN hokusai test --build
   deploy-staging:
     docker:
       - image: artsy/hokusai

.env.test

@@ -23,3 +23,8 @@ GEMINI_KEY=REPLACE
 
 # Needed to link Reaction: `yarn link @artsy/reaction`
 GRAPHQL_ENDPOINT=https://metaphysics-staging.artsy.net
+
+# Token used to authenticate with the code coverage tracking tool Codecov.
+# Token not needed when running tests during dev, intended to only be set
+# during CI.
+CODECOV_TOKEN

.gitignore

@@ -21,3 +21,6 @@ data
 /public
 /src/client/public/assets
 /node_modules
+
+coverage.lcov
+.nyc_output/

Dockerfile

@@ -2,7 +2,7 @@ FROM node:10.13-alpine
 ARG COMMIT_HASH
 RUN test -n "$COMMIT_HASH"
 
-RUN apk add curl git nginx
+RUN apk add curl git nginx bash
 
 # Set up deploy user and working directory
 RUN adduser -D -g '' deploy

README.md

@@ -2,6 +2,7 @@
 
 [Positron](https://github.com/artsy/positron) is Artsy Writer or the editorial tool for Artsy.
 
+[![codecov](https://codecov.io/gh/artsy/positron/branch/master/graph/badge.svg)](https://codecov.io/gh/artsy/positron)
 ![ArtsyWriter](/doc/images/ArtsyWriter.png)
 
 ## Meta

package.json

@@ -14,13 +14,18 @@
     "prettier-project": "yarn run prettier-write 'src/**/*.{ts,tsx,js,jsx}'",
     "prettier-write": "yarn run prettier --write",
     "mocha": "sh scripts/mocha.sh",
+    "jest": "sh scripts/jest.sh",
     "start": "sh scripts/start.sh",
     "production": "sh scripts/production.sh",
     "publish-assets": "sh scripts/publish-assets.sh",
     "task": "node -r coffeescript/register -r @babel/register -r dotenv/config",
     "test:watch": "yarn jest -- --watch --runInBand",
     "test": "sh scripts/test.sh",
-    "type-check": "tsc --pretty --noEmit"
+    "type-check": "tsc --pretty --noEmit",
+    "normalize-jest-coverage": "node scripts/normalize-jest-coverage.js",
+    "create-merged-coverage": "nyc report --reporter=text-lcov > coverage.lcov",
+    "report-coverage": "./scripts/codecov -C $(cat COMMIT_HASH.txt) -p app/ -f coverage.lcov",
+    "publish-coverage": "yarn normalize-jest-coverage && yarn create-merged-coverage && yarn report-coverage"
   },
   "resolutions": {
     "babel-core": "^7.0.0-0",
@@ -181,6 +186,8 @@
     "json-loader": "^0.5.7",
     "lint-staged": "^7.2.2",
     "mocha": "^3.1.2",
+    "mocha-lcov-reporter": "^1.3.0",
+    "nyc": "^13.1.0",
     "progress-bar-webpack-plugin": "^1.10.0",
     "raf": "^3.4.0",
     "react-addons-test-utils": "^15.4.2",