Add test coverage in CI

Author: ehmicky

.travis.yml

@@ -11,10 +11,17 @@ script: npm test
 # without. We only want to build the one with the tag, because it's the one
 # that runs the deployment stage
 if: '!(commit_message =~ /^Release/ && tag is blank)'
-# Deployment must happen after tests for the whole matrix have been performed,
-# so we use `jobs.include` with a different `stage`
 jobs:
   include:
+    # Test coverage check must happen after tests for the whole matrix have
+    # been performed, so we get the merged coverage map
+    - stage: Coverage check
+      os: linux
+      script: npm run check-coverage
+      # If CI fails, codecov does not post a bot comment on PR, so we skip it
+      if: type != pull_request && branch == master
+    # Deployment must happen after tests for the whole matrix have been
+    # performed, so we use `jobs.include` with a different `stage`
     - stage: Deploy
       os: linux
       # We have already run tests

gulp/tasks/coverage.js

@@ -0,0 +1,46 @@
+'use strict'
+
+const {
+  env: { TRAVIS_REPO_SLUG, TRAVIS_COMMIT },
+} = require('process')
+
+const isCi = require('is-ci')
+const fetch = require('cross-fetch')
+const PluginError = require('plugin-error')
+
+// In CI, once each environment has sent their test coverage maps, we check that
+// when merging them we are above the minimum threshold
+const checkCoverage = async function() {
+  if (!isCi) {
+    return
+  }
+
+  const coverage = await getCoverage()
+
+  if (coverage < COVERAGE_THRESHOLD) {
+    throw new PluginError(
+      'gulp-codecov-check',
+      `Test coverage is ${coverage}% but should be at least ${COVERAGE_THRESHOLD}%`,
+    )
+  }
+}
+
+const getCoverage = async function() {
+  const codecovUrl = `https://codecov.io/api/gh/${TRAVIS_REPO_SLUG}/commit/${TRAVIS_COMMIT}`
+  const response = await fetch(codecovUrl)
+  const {
+    commit: {
+      // eslint-disable-next-line id-length
+      totals: { c: coverage },
+    },
+  } = await response.json()
+
+  const coverageA = Number(coverage)
+  return coverageA
+}
+
+const COVERAGE_THRESHOLD = 100
+
+module.exports = {
+  checkCoverage,
+}

gulp/tasks/index.js

@@ -5,6 +5,7 @@ module.exports = {
   ...require('./test'),
   ...require('./check'),
   ...require('./unit'),
+  ...require('./coverage'),
   ...require('./build'),
   ...require('./emit'),
 }

package-lock.json

@@ -10,7 +10,8 @@
   "scripts": {
     "build": "gulp build",
     "test": "npm run build && gulp test",
-    "release": "npm test && release-it"
+    "release": "npm test && release-it",
+    "check-coverage": "gulp checkCoverage"
   },
   "husky": {
     "hooks": {
@@ -61,6 +62,7 @@
     "@babel/plugin-transform-runtime": "^7.2.0",
     "@babel/preset-env": "^7.2.0",
     "ava": "^1.0.0-rc.2",
+    "cross-fetch": "^2.2.3",
     "eslint": "^5.9.0",
     "eslint-config-prettier": "^3.3.0",
     "eslint-config-standard": "^12.0.0",