Disable animations for UI regression runs

src/engine-scripts/puppet/jsReady.js

@@ -0,0 +1,40 @@
+module.exports = async (page) => {
+	await page.emulateMediaFeatures([
+		{ name: 'prefers-reduced-motion', value: 'reduce' },
+	]);
+	await page.evaluate( async () => {
+		const skin = mw.config.get( 'skin' );
+		let moduleName;
+		switch( skin ) {
+			case 'vector-2022':
+				moduleName = 'skins.vector.js';
+				break;
+			case 'vector':
+				moduleName = 'skins.vector.legacy.js';
+				break;
+			default:
+				return true;
+		}
+
+		// Poll the state of the module until it is ready.
+		await new Promise((resolve) => {
+			const id = setInterval(() => {
+				if ( mw.loader.getState( moduleName ) === 'ready' ) {
+					clearInterval( id );
+					resolve(true);
+				}
+			}, 500 );
+		});
+
+		// Wait until the next frame before resolving. collapsibleTabs.js in Vector
+		// and Vector-2022 make use of rAF.
+		return new Promise( resolve => {
+			requestAnimationFrame( () => {
+				requestAnimationFrame( () => {
+					resolve();
+				} );
+			} );
+		} );
+
+	});
+};

src/engine-scripts/puppet/onReady.js

@@ -9,5 +9,8 @@ module.exports = async (page, scenario, vp) => {
     await require('./sidebarState')(page, hashtags);
     await require('./userMenuState')(page, hashtags);
   }
+
+  // Make sure the main skin JavaScript module has loaded.
+  await require('./jsReady')(page);
   // add more ready handlers here...
 };