chore: update jest to v23 (#885)

* chore: update jest to v23

* add changelog

CHANGELOG.md

@@ -35,13 +35,14 @@ Thank you to the following contributors who helped with this release:
 - Fix phrase emphasis not italicized [\#850](https://github.com/facebook/Docusaurus/pull/850)
 - Blogpost summary for blog feed is now properly truncated [\#880](https://github.com/facebook/Docusaurus/pull/880)
 
-**Chores**
+**Chore and Maintenance**
 - Remove unused files [\#881](https://github.com/facebook/Docusaurus/pull/881)
 - Add prerelease script for Docusaurus [\#876](https://github.com/facebook/Docusaurus/pull/876)
 - Improve readme [\#866](https://github.com/facebook/Docusaurus/pull/866) 
 - Refactor & add more tests for Docusaurus [\#839](https://github.com/facebook/Docusaurus/pull/839) [\#847](https://github.com/facebook/Docusaurus/pull/847) [\#854](https://github.com/facebook/Docusaurus/pull/854) [\#856](https://github.com/facebook/Docusaurus/pull/856) 
 - Add ESLint [\#836](https://github.com/facebook/Docusaurus/pull/836) [\#837](https://github.com/facebook/Docusaurus/pull/837) [\#841](https://github.com/facebook/Docusaurus/pull/841) [\#846](https://github.com/facebook/Docusaurus/pull/846)
-- Update [code of conduct.md](https://github.com/facebook/Docusaurus/commit/3c1363da1bd445029d7034b0575f69a7077321c3)
+- Update [code of conduct](https://github.com/facebook/Docusaurus/commit/3c1363da1bd445029d7034b0575f69a7077321c3)
+- Update jest to v23 [\#885](https://github.com/facebook/Docusaurus/pull/885)
 
 ## [1.3.2] - 2018-07-06
 

package.json

@@ -40,7 +40,8 @@
     }
   },
   "jest": {
-    "testPathIgnorePatterns": ["/node_modules/", "__fixtures__"]
+    "testPathIgnorePatterns": ["/node_modules/", "__fixtures__"],
+    "testURL": "http://localhost/"
   },
   "bin": {
     "docusaurus-start": "./lib/start-server.js",
@@ -107,7 +108,7 @@
     "front-matter": "^2.3.0",
     "glob-promise": "^3.3.0",
     "husky": "^0.14.3",
-    "jest": "^21.2.1",
+    "jest": "^23.4.2",
     "lint-staged": "^7.2.0",
     "prettier": "^1.13.7",
     "rimraf": "^2.6.2"