fix(MissingObserver polyfill): add MissingObserver polyfill for jest environment

affects: @patternfly/react-console, patternfly-react

Referenced from noVNC (@novnc/nvnc/core/util/events.js).

Workaround for the 'jest' testing only
since the MutationObserver is available in browsers otherwise.

Attempt to fix the issue by using
'browser' jest configuration option did not work in this case.

Author: mareklibra

package.json

@@ -72,6 +72,7 @@
     "lerna-semantic-release": "^9.1.0",
     "lint-staged": "^7.0.4",
     "lodash": "^4.17.0",
+    "mutation-observer": "^1.0.3",
     "node-sass": "^4.8.3",
     "prettier": "^1.11.1",
     "prettier-eslint": "^8.8.1",

test.env.js

@@ -2,4 +2,10 @@ import 'raf/polyfill';
 import { configure } from 'enzyme';
 import Adapter from 'enzyme-adapter-react-16';
 
+const MutationObserverPolyfill = require('mutation-observer');
+
+// referenced from '@novnc/nvnc/core/util/events.js'
+// The MutationObserver is available in supported browsers, this is workaround for "jest"
+global.MutationObserver = global.MutationObserver || MutationObserverPolyfill;
+
 configure({ adapter: new Adapter() });

yarn.lock

@@ -8393,6 +8393,10 @@ [email protected]:
   version "2.1.1"
   resolved "https://registry.yarnpkg.com/ms/-/ms-2.1.1.tgz#30a5864eb3ebb0a66f2ebe6d727af06a09d86e0a"
 
+mutation-observer@^1.0.3:
+  version "1.0.3"
+  resolved "https://registry.yarnpkg.com/mutation-observer/-/mutation-observer-1.0.3.tgz#42e9222b101bca82e5ba9d5a7acf4a14c0f263d0"
+
 [email protected]:
   version "0.0.6"
   resolved "https://registry.yarnpkg.com/mute-stream/-/mute-stream-0.0.6.tgz#48962b19e169fd1dfc240b3f1e7317627bbc47db"