Widget: Support mixins

Fixes #12601
Closes gh-1554

tests/unit/widget/core.js

@@ -476,6 +476,85 @@ test( "._superApply()", function() {
	delete $.fn.testWidget2;
});

test( "mixins", function() {
	expect( 5 );

	var mixin1 = {
		foo: function() {
			equal( method, "foo", "Methods from first mixin are copied over" );
		}
	};
	var mixin2 = {
		bar: function() {
			equal( method, "bar", "Methods from second mixin are copied over" );
		}
	};
	var prototype = {
		baz: function() {
			equal( method, "baz", "Methods from protoype are copied over" );
		}
	};
	var existingBar = mixin2.bar;
	var method;

	$.widget( "ui.testWidget", [ mixin1, mixin2, prototype ] );
	method = "foo";
	$.ui.testWidget.prototype.foo();
	method = "bar";
	$.ui.testWidget.prototype.bar();
	method = "baz";
	$.ui.testWidget.prototype.baz();

	mixin1.foo = function() {
		ok( false, "Changes to a mixin don't change the prototype" );
	};
	method = "foo";
	$.ui.testWidget.prototype.foo();

	$.ui.testWidget.prototype.bar = function() {};
	strictEqual( mixin2.bar, existingBar, "Changes to a prototype don't change the mixin" );
});

test( "mixins with inheritance", function() {
	expect( 4 );

	var mixin1 = {
		foo: function() {
			equal( method, "foo", "Methods from first mixin are copied over" );
		}
	};
	var mixin2 = {
		bar: function() {
			equal( method, "bar", "Methods from second mixin are copied over" );
		}
	};
	var parentPrototype = {
		baz: function() {
			equal( method, "baz", "Methods from parent protoype are copied over" );
		}
	};
	var childPrototype = {
		qux: function() {
			equal( method, "qux", "Methods from child protoype are copied over" );
		}
	};
	var method;

	$.widget( "ui.testWidget", [ mixin1, parentPrototype ] );
	$.widget( "ui.testWidget2", $.ui.testWidget, [ mixin2, childPrototype ] );
	method = "foo";
	$.ui.testWidget2.prototype.foo();
	method = "bar";
	$.ui.testWidget2.prototype.bar();
	method = "baz";
	$.ui.testWidget2.prototype.baz();
	method = "qux";
	$.ui.testWidget2.prototype.qux();

	delete $.ui.testWidget2;
	delete $.fn.testWidget2;
});

test( ".option() - getter", function() {
	expect( 6 );
	$.widget( "ui.testWidget", {

ui/widget.js

@@ -62,6 +62,10 @@ $.widget = function( name, base, prototype ) {
		base = $.Widget;
	}

	if ( $.isArray( prototype ) ) {
		prototype = $.extend.apply( null, [ {} ].concat( prototype ) );
	}

	// create selector for plugin
	$.expr[ ":" ][ fullName.toLowerCase() ] = function( elem ) {
		return !!$.data( elem, fullName );