Build: Add macOS and Windows to the Travis CI test matrix

Update grunt-contrib-qunit to 3.1.0, because grunt-contrib-qunit 3.0.1
uses a pinned (older) version of puppeteer. The older puppteer used an
older version of Chrome, which is incompatible with Windows Server 2016,
which is what Travis CI offers. AppVeyor was using Windows Server 2012,
whih was not affected by that Chrome bug.

Ref gruntjs/grunt-contrib-qunit#154.

For Windows, the build script is limited to `test:main`. This is the
same as it was before with AppVeyor, because the CLI tests are not passing
on Windows currently. Ref #1359.

Fixes #1347.

.gitattributes

@@ -5,3 +5,5 @@
 *.js eol=lf
 *.json eol=lf
 *.html eol=lf
+# TODO: Rename to qunit.js?
+bin/qunit eol=lf

.travis.yml

@@ -1,15 +1,28 @@
+os: linux
 language: node_js
 node_js:
-  - "6"
-  - "8"
   - "10"
+  - "8"
+  - "6"
 env:
   - NPM_SCRIPT=test
-  - NPM_SCRIPT=test:cli
 matrix:
   fast_finish: true
   include:
-    - node_js: "10"
+    # On Windows, test only the last LTS.
+    - os: windows
+      node_js: "10"
+      # On Windows, run test:main only instead of test.
+      # https://github.com/qunitjs/qunit/issues/1359
+      # On Windows, disable yarn-gpg due to it causing the
+      # build to never finish (background process)
+      # https://travis-ci.community/t/timeout-after-build-finished-and-succeeded/1336
+      env: NPM_SCRIPT=test:main YARN_GPG=no
+    # On Mac, test only the last LTS.
+    - os: osx
+      node_js: "10"
+    - os: linux
+      node_js: "10"
       env: NPM_SCRIPT=coverage
 script:
   - npm run $NPM_SCRIPT

README.md

@@ -1,5 +1,4 @@
-[![Travis Build Status](https://travis-ci.org/qunitjs/qunit.svg?branch=master)](https://travis-ci.org/qunitjs/qunit)
-[![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/github/qunitjs/qunit?svg=true&branch=master)](https://ci.appveyor.com/project/leobalter/qunit)
+[![Build Status](https://travis-ci.org/qunitjs/qunit.svg?branch=master)](https://travis-ci.org/qunitjs/qunit)
 [![Coverage Status](https://coveralls.io/repos/qunitjs/qunit/badge.svg)](https://coveralls.io/github/qunitjs/qunit)
 [![Chat on Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/qunitjs/qunit?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![FOSSA Status](https://app.fossa.io/api/projects/git%2Bhttps%3A%2F%2Fgithub.com%2Fqunitjs%2Fqunit.svg?type=shield)](https://app.fossa.io/projects/git%2Bhttps%3A%2F%2Fgithub.com%2Fqunitjs%2Fqunit?ref=badge_shield)

package.json

@@ -60,7 +60,7 @@
     "grunt-concurrent": "2.3.1",
     "grunt-contrib-connect": "1.0.2",
     "grunt-contrib-copy": "1.0.0",
-    "grunt-contrib-qunit": "3.0.1",
+    "grunt-contrib-qunit": "3.1.0",
     "grunt-contrib-watch": "1.1.0",
     "grunt-coveralls": "2.0.0",
     "grunt-eslint": "20.1.0",
@@ -79,9 +79,10 @@
   "scripts": {
     "build": "grunt build",
     "dev": "grunt watch",
-    "test": "grunt",
-    "coverage": "grunt coverage",
-    "test:cli": "grunt build && bin/qunit test/cli/*.js"
+    "test": "grunt && bin/qunit test/cli/*.js",
+    "test:main": "grunt",
+    "test:cli": "grunt build && bin/qunit test/cli/*.js",
+    "coverage": "grunt coverage"
   },
   "commitplease": {
     "components": [