Add Coveralls to package.json [1/2] (#21017)

Summary:
Adds a new step to the test suite. Test coverage is now collected and sent to Coveralls.

Initial configuration is limited to the Libraries/ and local-cli/ directories. Please let me know if additional directories should be considered.

I have enabled this repo on the coveralls service. The coveralls token has been added to React Native's Circle CI environment variables.

- Track coverage on PRs, and fail PRs that lower the coverage %
- Increase coverage :)

[INTERNAL] [ENHANCEMENT] [.circleci/config.yml] - Start tracking code coverage (JS)

Pull Request resolved: #21017

Differential Revision: D9724396

Pulled By: hramos

fbshipit-source-id: 61da4478877805f9a9a3c9670b54ddc4e40e958b

.circleci/config.yml

@@ -200,6 +200,13 @@ aliases:
       ./scripts/circleci/validate_yarn_lockfile.sh
     when: always
 
+  - &js-coverage
+    name: Test coverage
+    command: |
+      yarn test --coverage --maxWorkers=2
+      cat ./coverage/lcov.info | ./node_modules/.bin/coveralls
+    when: always
+
   - &download-dependencies-gradle
     name: Download Dependencies Using Gradle
     command: ./scripts/circleci/gradle_download_deps.sh
@@ -626,6 +633,17 @@ jobs:
           when: always
       - save-cache: *save-cache-analysis
 
+  # Test Coverage
+  js_coverage:
+    <<: *js_defaults
+    steps:
+      - checkout
+      - restore-cache: *restore-yarn-cache
+      - run: *yarn
+      - run: *js-coverage
+      - store_artifacts:
+          path: ~/react-native/coverage/
+
   # Publishes new version onto npm
   # Only works on stable branches when a properly tagged commit is pushed
   publish_npm_package:
@@ -720,6 +738,8 @@ workflows:
       - test_node10:
           filters: *filter-ignore-gh-pages
 
+  releases:
+    jobs:
       # Only runs on vX.X.X tags if all tests are green
       - publish_npm_package:
           filters:
@@ -730,8 +750,16 @@ workflows:
             tags:
               only: /v[0-9]+(\.[0-9]+)*(\-rc(\.[0-9]+)?)?/
 
+  analysis:
+    jobs:
       # Run code checks on PRs from forks
       - analyze_pr:
           filters:
             branches:
               only: /^pull\/.*$/
+
+      # Gather coverage on master
+      - js_coverage:
+          filters:
+            branches:
+              only: master

package.json

@@ -88,7 +88,17 @@
       "denodeify",
       "fbjs"
     ],
-    "testEnvironment": "node"
+    "testEnvironment": "node",
+    "collectCoverageFrom": [
+      "Libraries/**/*.js",
+      "local-cli/**/*.js"
+    ],
+    "coveragePathIgnorePatterns": [
+      "/__tests__/",
+      "/vendor/",
+      "<rootDir>/Libraries/react-native/",
+      "<rootDir>/local-cli/templates/"
+    ]
   },
   "main": "Libraries/react-native/react-native-implementation.js",
   "files": [
@@ -212,6 +222,7 @@
     "babel-eslint": "9.0.0",
     "babel-generator": "^6.26.0",
     "detox": "9.0.4",
+    "coveralls": "^3.0.2",
     "eslint": "5.1.0",
     "eslint-config-fb-strict": "22.1.0",
     "eslint-config-fbjs": "2.0.1",