Fix for testing against electron 3 on windows

electron/electron#13039 caused our tests to fail on windows because we pass URL arguments. So, we need to add a '--' to the arguments to work around the issue.

lib/test-support/test-main.js

@@ -9,7 +9,7 @@ let mainWindow = null;
 // The testUrl is a file: url pointing to our index.html, with some query
 // params we need to preserve for testem. So we need to register our ember
 // protocol accordingly.
-let [, , indexUrl, testemUrl] = process.argv;
+let [, , , indexUrl, testemUrl] = process.argv;
 // Undo workaround for windows (see test-runner.js for explanation)
 indexUrl = indexUrl.replace(/__amp__/g, '&');
 let {

lib/test-support/test-runner.js

@@ -54,7 +54,15 @@ if (require.main === module) {
   testUrl = testUrl.replace(/&/g, '__amp__');
 
   // Start electron
-  efStart({ appPath: buildDir, dir: buildDir, args: [testUrl, testemUrl] }).then(({ pid }) => {
+  efStart({
+    appPath: buildDir,
+    dir: buildDir,
+    args: [
+      '--', // needed because https://github.com/electron/electron/pull/13039
+      testUrl,
+      testemUrl,
+    ],
+  }).then(({ pid }) => {
     // Clean up when we're killed
     process.on('SIGTERM', () => {
       treeKill(pid);