Add tests for when a Symbol polyfill is present on the page

Author: Will Binns-Smith

.travis.yml

@@ -12,6 +12,7 @@ script:
   - 'npm test'
   # Run browser tests on one node version.
   - 'if [ "${TRAVIS_PULL_REQUEST}" = "false" ] && [ "${TRAVIS_NODE_VERSION}" = "stable" ]; then npm run test:browsers; fi'
+  - 'if [ "${TRAVIS_PULL_REQUEST}" = "false" ] && [ "${TRAVIS_NODE_VERSION}" = "stable" ]; then npm run test:browsers:polyfills; fi'
 addons:
   sauce_connect: true
   hosts:

package.json

@@ -17,6 +17,7 @@
   },
   "devDependencies": {
     "airtap": "~1.0.0",
+    "core-js": "^3.6.5",
     "is-async-supported": "~1.2.0",
     "object.assign": "~4.1.0",
     "object.entries": "^1.1.0",
@@ -40,6 +41,8 @@
   "scripts": {
     "test": "node test/node/index.js",
     "test:browsers": "airtap test/browser/index.js",
+    "test:browsers:with-polyfills": "airtap test/browser/with-polyfills.js",
+    "test:browsers:with-polyfills:local": "npm run test:browsers:with-polyfills -- --local",
     "test:browsers:local": "npm run test:browsers -- --local"
   }
 }

test/browser/with-polyfills.js

@@ -0,0 +1,2 @@
+require('core-js');
+require('./index.js');