Add Karma Test Runner

* update package.json w/ karma dependencies
* add npm test script
* add node_modules to .gitignore

.gitignore

@@ -2,4 +2,5 @@ a.out
 *.class
 /**/java/out/*
 /**/.idea/workspace.xml
-/lib/
+/lib/
+/node_modules/

karma.conf.js

@@ -0,0 +1,42 @@
+'use strict';
+
+module.exports = function (config) {
+    config.set({
+
+        // base path, that will be used to resolve files and exclude
+        basePath: 'src',
+
+        // frameworks to use
+        frameworks: ['jasmine'],
+
+        // list of files / patterns to load in the browser
+        files: [
+            'Layout.js',
+            'Layout-test-utils.js',
+            '__tests__/Layout-test.js',
+            '__tests__/Layout-consts-test.js'
+        ],
+
+        plugins: [
+            'karma-chrome-launcher',
+            'karma-jasmine'
+        ],
+
+        // web server port
+        port: 9876,
+
+        // enable / disable colors in the output (reporters and logs)
+        colors: true,
+
+        // level of logging
+        // possible values: config.LOG_DISABLE || config.LOG_ERROR || config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
+        logLevel: config.LOG_INFO,
+
+        browsers: ['Chrome'],
+
+        // If browser does not capture in given timeout [ms], kill it
+        captureTimeout: 60000,
+
+        singleRun: false
+    });
+};

package.json

@@ -4,7 +4,7 @@
   "description": "Reimplementation of CSS layout using pure JavaScript",
   "main": "src/Layout.js",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "./node_modules/karma/bin/karma start ./karma.conf.js --single-run"
   },
   "repository": {
     "type": "git",
@@ -15,5 +15,11 @@
   "bugs": {
     "url": "https://github.com/facebook/css-layout/issues"
   },
-  "homepage": "https://github.com/facebook/css-layout"
+  "homepage": "https://github.com/facebook/css-layout",
+  "devDependencies": {
+    "jasmine-core": "^2.2.0",
+    "karma": "^0.12.31",
+    "karma-chrome-launcher": "^0.1.7",
+    "karma-jasmine": "^0.3.5"
+  }
 }