Hygiene: replace jQuery.noop dependency

Replace $.noop dependency with inline empty function.

The tests relied on a single function instance to pass. A toString()
comparison of the noop function cannot be used as they differ when
coverage is enabled.

Change-Id: I641801593beb240a8f7d06e388a0e41dc8a25bc6

src/getPageviewTracker.js

@@ -89,7 +89,7 @@ function getPageviewTracker( config, loader, trackerGetter, sendBeacon ) {
 			sendBeacon( url );
 		} );
 	};
-	return config.get( 'wgPopupsVirtualPageViews' ) ? pageviewTracker : $.noop;
+	return config.get( 'wgPopupsVirtualPageViews' ) ? pageviewTracker : () => {};
 }
 
 /**

src/index.js

@@ -53,7 +53,7 @@ const mw = mediaWiki,
  *
  * If logging metrics to StatsD is enabled for the duration of the user's
  * session, then the appriopriate function is `mw.track`; otherwise it's
- * `$.noop`.
+ * `() => {}`.
  *
  * [0]: https://github.com/wikimedia/mediawiki-extensions-WikimediaEvents/blob/29c864a0/modules/ext.wikimediaEvents.statsd.js
  *
@@ -63,7 +63,7 @@ const mw = mediaWiki,
  * @return {EventTracker}
  */
 function getStatsvTracker( user, config, experiments ) {
-	return isStatsvEnabled( user, config, experiments ) ? mw.track : $.noop;
+	return isStatsvEnabled( user, config, experiments ) ? mw.track : () => {};
 }
 
 /**
@@ -72,7 +72,7 @@ function getStatsvTracker( user, config, experiments ) {
  *
  * If logging EventLogging events is enabled for the duration of the user's
  * session, then the appriopriate function is `mw.track`; otherwise it's
- * `$.noop`.
+ * `() => {}`.
  *
  * [0]: https://github.com/wikimedia/mediawiki-extensions-EventLogging/blob/d1409759/modules/ext.eventLogging.subscriber.js
  *
@@ -86,7 +86,7 @@ function getEventLoggingTracker( user, config, window ) {
 		user,
 		config,
 		window
-	) ? mw.track : $.noop;
+	) ? mw.track : () => {};
 }
 
 /**

src/previewBehavior.js

@@ -2,8 +2,7 @@
  * @module previewBehaviour
  */
 
-const mw = mediaWiki,
-	$ = jQuery;
+const mw = mediaWiki;
 
 /**
  * A collection of event handlers specific to how the user interacts with all
@@ -34,7 +33,7 @@ const mw = mediaWiki,
  * @return {ext.popups.PreviewBehavior}
  */
 export default function createPreviewBehavior( user, actions ) {
-	let settingsUrl, showSettings = $.noop;
+	let settingsUrl, showSettings = () => {};
 
 	if ( user.isAnon() ) {
 		showSettings = ( event ) => {

tests/node-qunit/previewBehavior.test.js

@@ -42,15 +42,18 @@ QUnit.test( 'it shouldn\'t set the settingsUrl if the user is logged out', funct
 } );
 
 QUnit.test( 'it shouldn\'t set a showSettings handler if the user is logged in', function ( assert ) {
-	const user = createStubUser( /* isAnon = */ false ),
-		actions = {},
+	const
+		user = createStubUser( /* isAnon = */ false ),
+		event = {
+			preventDefault: this.sandbox.spy()
+		},
+		actions = {
+			showSettings: () => assert.ok( false, 'No show settings handler is set.' )
+		},
 		behavior = createPreviewBehavior( user, actions );
 
-	assert.strictEqual(
-		behavior.showSettings,
-		$.noop,
-		'No show settings handler is set.'
-	);
+	behavior.showSettings( event );
+	assert.ok( true );
 } );
 
 QUnit.test( 'it should set a showSettings handler if the user is logged out', function ( assert ) {