ONOS-6524: Added Code Coverage tools to gulp

When `gulp test` is executed, Karma will now generate an interactive html report for code coverage in each file. The folder can be found in web/gui/src/main/webapp/tests/coverage

Change-Id: I951ac1bea7f3f0ca35deb9cc823bb883bcd9f8a5
diff --git a/web/gui/src/main/webapp/tests/karma.conf.js b/web/gui/src/main/webapp/tests/karma.conf.js
index 265e325..8e9cd39 100644
--- a/web/gui/src/main/webapp/tests/karma.conf.js
+++ b/web/gui/src/main/webapp/tests/karma.conf.js
@@ -56,14 +56,18 @@
     // preprocess matching files before serving them to the browser
     // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
     preprocessors: {
+        '../app/**/*.js': 'coverage'
     },
 
 
     // test results reporter to use
     // possible values: 'dots', 'progress'
     // available reporters: https://npmjs.org/browse/keyword/karma-reporter
-    reporters: ['mocha'],
-
+    reporters: ['mocha', 'coverage'],
+    coverageReport: {
+        type: 'html',
+        dir : 'coverage/'
+    },
 
     // web server port
     port: 9876,