Tests: Account for extra focus/blur listeners in jQuery >=3.4

jQuery >=3.4.0 uses a special focus/blur handler pair
needed to fix various issues with checkboxes/radio buttons
as well as being able to pass data in focus triggers.
However, this leaves dummy focus & blur events if any of these
events were ever listened to at a particular element. There's not
a lot UI can do to fix this so we now just skip these handlers for
data comparisons in tests.

Ref jquery/jquery#4496
Closes gh-1930

Co-authored-by: Richard Gibson <richard.gibson@gmail.com>

Author: mgol

tests/lib/qunit-assert-domequal.js

@@ -93,6 +93,28 @@ function getElementStyles( elem ) {
 	return styles;
 }
 
+// Returns 0 if v1 == v2, -1 if v1 < v2, 1 if v1 > v2
+function compareVersions( v1, v2 ) {
+	var i,
+		rVersionParts = /^(\d+)\.(\d+)\.(\d+)/,
+		v1p = rVersionParts.exec( v1 ) || [ ],
+		v2p = rVersionParts.exec( v2 ) || [ ];
+
+	for ( i = 1; i <= 3; i++ ) {
+		if ( +v1p[ i ] > +v2p[ i ] ) {
+			return 1;
+		}
+		if ( +v1p[ i ] < +v2p[ i ] ) {
+			return -1;
+		}
+	}
+	return 0;
+}
+
+function jQueryVersionSince( version ) {
+	return compareVersions( $.fn.jquery, version ) >= 0;
+}
+
 function extract( selector, message ) {
 	var elem = $( selector );
 	if ( !elem.length ) {
@@ -113,6 +135,54 @@ function extract( selector, message ) {
 	} );
 	result.style = getElementStyles( elem[ 0 ] );
 	result.events = $._data( elem[ 0 ], "events" );
+
+	// jQuery >=3.4.0 uses a special focus/blur handler pair
+	// needed to fix various issues with checkboxes/radio buttons
+	// as well as being able to pass data in focus triggers.
+	// However, this leaves dummy focus & blur events if any of these
+	// events were ever listened to at a particular element. There's not
+	// a lot UI can do to fix this so just skip these handlers for
+	// data comparisons in tests.
+	// See https://github.com/jquery/jquery/issues/4496
+	if ( result.events && jQueryVersionSince( "3.4.0" ) ) {
+		var i, eventDataList, eventData;
+		$.each( [ "focus", "blur" ], function( index, eventType ) {
+			if ( !result.events[ eventType ] ) {
+				return;
+			}
+
+			// Only the special internal handlers
+			// have the namespace field set to boolean `false`;
+			// filter them out.
+			result.events[ eventType ] = result.events[ eventType ].filter( function( eventData ) {
+				return eventData.namespace !== false;
+			} );
+
+			eventDataList = result.events[ eventType ];
+			for ( i = eventDataList.length - 1; i > -1; i-- ) {
+				eventData = eventDataList[ i ];
+
+				// Only these special jQuery internal handlers
+				// have the `namespace` field set to `false`;
+				// all other events use a string value, possibly
+				// an empty string if no namespace was set.
+				if ( eventData.namespace === false ) {
+					eventDataList.splice( i, 1 );
+				}
+			}
+
+			// Remove empty eventData collections to follow jQuery behavior.
+			if ( !eventDataList.length ) {
+				delete result.events[ eventType ];
+			}
+		} );
+
+		// Simulate empty events collections removal to follow jQuery behavior.
+		if ( !Object.keys( result.events ).length ) {
+			result.events = undefined;
+		}
+	}
+
 	result.data = $.extend( {}, elem.data() );
 	delete result.data[ $.expando ];
 	children = elem.children();