add Appveyor to test on Windows

Author: sindresorhus

appveyor.yml

@@ -0,0 +1,22 @@
+environment:
+  matrix:
+    - nodejs_version: '5'
+    - nodejs_version: '4'
+    - nodejs_version: '0.12'
+    - nodejs_version: '0.10'
+install:
+  - ps: Install-Product node $env:nodejs_version
+  - set CI=true
+  - npm -g install npm@latest
+  - set PATH=%APPDATA%\npm;%PATH%
+  - npm install
+matrix:
+  fast_finish: true
+build: off
+version: '{build}'
+shallow_clone: true
+clone_depth: 1
+test_script:
+  - node --version
+  - npm --version
+  - npm run test-win

package.json

@@ -33,6 +33,7 @@
   },
   "scripts": {
     "test": "xo && nyc tape test/*.js | tap-dot",
+    "test-win": "tape test/*.js | tap-dot",
     "coveralls": "nyc report --reporter=text-lcov | coveralls"
   },
   "files": [

readme.md

@@ -2,7 +2,7 @@
 
 > Futuristic test runner
 
-[![Build Status](https://travis-ci.org/sindresorhus/ava.svg?branch=master)](https://travis-ci.org/sindresorhus/ava) [![Coverage Status](https://coveralls.io/repos/sindresorhus/ava/badge.svg?branch=master&service=github)](https://coveralls.io/github/sindresorhus/ava?branch=master) [![Join the chat](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/sindresorhus/ava?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Build Status: Linux](https://travis-ci.org/sindresorhus/ava.svg?branch=master)](https://travis-ci.org/sindresorhus/ava) [![Build status: Windows](https://ci.appveyor.com/api/projects/status/igogxrcmhhm085co/branch/master?svg=true)](https://ci.appveyor.com/project/sindresorhus/ava/branch/master) [![Coverage Status](https://coveralls.io/repos/sindresorhus/ava/badge.svg?branch=master&service=github)](https://coveralls.io/github/sindresorhus/ava?branch=master) [![Join the chat](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/sindresorhus/ava?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
 Even though JavaScript is single-threaded, IO in Node.js can happen in parallel due to its async nature. AVA takes advantage of this and runs your tests concurrently, which is especially beneficial for IO heavy tests. In addition, test files are run in parallel as separate processes, giving you even better performance and a isolated environment for each test file. [Switching](https://github.com/sindresorhus/pageres/commit/663be15acb3dd2eb0f71b1956ef28c2cd3fdeed0) from Mocha to AVA in Pageres brought the test time down from 31 sec to 11 sec. Having tests run concurrently forces you to write atomic tests, meaning tests that don't depend on global state or the state of other tests, which is a great thing!