test runner: adding more tests for attr(). Related to [5574] and [5683].

test/unit/core.js

@@ -320,7 +320,7 @@ test("index(Object)", function() {
 });
 
 test("attr(String)", function() {
-	expect(20);
+	expect(26);
 	equals( $('#text1').attr('value'), "Test", 'Check for value attribute' );
 	equals( $('#text1').attr('value', "Test2").attr('defaultValue'), "Test", 'Check for defaultValue attribute' );
 	equals( $('#text1').attr('type'), "text", 'Check for type attribute' );
@@ -343,6 +343,27 @@ test("attr(String)", function() {
 
 	$('<a id="tAnchor5"></a>').attr('href', '#5').appendTo('#main'); // using innerHTML in IE causes href attribute to be serialized to the full path
 	equals( $('#tAnchor5').attr('href'), "#5", 'Check for non-absolute href (an anchor)' );
+
+
+	// Related to [5574] and [5683]
+	var body = document.body, $body = $(body);
+
+	ok( $body.attr('foo') === undefined, 'Make sure that a non existent attribute returns undefined' );
+	ok( $body.attr('nextSibling') === null, 'Make sure a null expando returns null' );
+	
+	body.setAttribute('foo', 'baz');
+	equals( $body.attr('foo'), 'baz', 'Make sure the dom attribute is retrieved when no expando is found' );
+	
+	body.foo = 'bar';
+	equals( $body.attr('foo'), 'bar', 'Make sure the expando is preferred over the dom attribute' );
+	
+	$body.attr('foo','cool');
+	equals( $body.attr('foo'), 'cool', 'Make sure that setting works well when both expando and dom attribute are available' );
+	
+	body.foo = undefined;
+	ok( $body.attr('foo') === undefined, 'Make sure the expando is preferred over the dom attribute, even if undefined' );
+	
+	body.removeAttribute('foo'); // Cleanup
 });
 
 if ( !isLocal ) {