added cross env support for npm start and chromedriver support for macOS

.github/CONTRIBUTING.md

@@ -117,7 +117,13 @@ We prefer using end-to-end visual regression tests (VRT) for pixel-perfect and w
 
 ### Running tests manually
 
-Download [ChromeDriver](https://sites.google.com/a/chromium.org/chromedriver/downloads) and extract to the project root.
+Download OS-specific version of [ChromeDriver](https://googlechromelabs.github.io/chrome-for-testing/) and extract to the project root.
+
+For MacOS
+
+   Give execute permission: `chmod +x ./chromedriver`
+
+   Remove quarantine flag: `xattr -d com.apple.quarantine ./chromedriver`
 
 Run `npm run browser`. It will open a new browser window to http://localhost:5001/**tests**/html/. Then, navigate to the test file.
 

package.json

@@ -70,7 +70,7 @@
     "precommit:typecheck:core": "cd packages && cd core && npm run precommit:typecheck",
     "precommit:typecheck:fluent-theme": "cd packages && cd fluent-theme && npm run precommit:typecheck",
     "prepare": "husky",
-    "start": "NODE_OPTIONS=--no-deprecation concurrently --kill-others --prefix-colors \"auto\" \"npm:start:*\"",
+    "start": "cross-env NODE_OPTIONS=--no-deprecation concurrently --kill-others --prefix-colors \"auto\" \"npm:start:*\"",
     "start:api": "cd packages && cd api && npm start",
     "start:bundle": "cd packages && cd bundle && npm start",
     "start:component": "cd packages && cd component && npm start",

packages/test/harness/src/host/dev/index.js

@@ -23,7 +23,7 @@ async function main() {
   const hostIP = await findHostIP();
   const localIP = await findLocalIP();
 
-  const service = await new ChromeServiceBuilder('./chromedriver.exe')
+  const service = await new ChromeServiceBuilder('./chromedriver')
     .addArguments('--allowed-ips', localIP)
     .setHostname(hostIP)
     .setStdio(['ignore', 'ignore', 'ignore'])