Get tests passing on Windows (#4579)

Closes #4564

.appveyor.yml

@@ -0,0 +1,15 @@
+version: '{build}'
+branches:
+  only: [master]
+init:
+- ps: Install-Product node 8
+install:
+- cmd: npm -v 
+- cmd: node -v 
+- cmd: npm install -g yarn
+- cmd: yarn
+cache:
+- node_modules
+build: off
+test_script:
+- cmd: yarn test

tests_integration/__tests__/plugin-extensions.js

@@ -1,7 +1,7 @@
 "use strict";
 
 const runPrettier = require("../runPrettier");
-const EOL = require("os").EOL;
+const EOL = "\n";
 
 describe("uses 'extensions' from languages to determine parser", () => {
   runPrettier("plugins/extensions", ["*.foo", "--plugin=./plugin"]).test({

tests_integration/__tests__/plugin-preprocess.js

@@ -1,7 +1,7 @@
 "use strict";
 
 const runPrettier = require("../runPrettier");
-const EOL = require("os").EOL;
+const EOL = "\n";
 
 describe("parser preprocess function is used to reshape input text", () => {
   runPrettier("plugins/preprocess", ["*.foo", "--plugin=./plugin"]).test({

tests_integration/__tests__/plugin-resolution.js

@@ -1,7 +1,7 @@
 "use strict";
 
 const runPrettier = require("../runPrettier");
-const EOL = require("os").EOL;
+const EOL = "\n";
 
 describe("automatically loads 'prettier-plugin-*'", () => {
   runPrettier("plugins/automatic", ["file.txt", "--parser=foo"]).test({