introduced local aliases

this improves readability somewhat (though it shouldn't be abused)

again leveraging IIFEs; arguments passed in below and accepted under a
different name

using regular local variables instead of the arguments trick for QUnit
to keep the IIFE's signature manageable

lib/main.js

@@ -1,9 +1,9 @@
-(function() {
+(function($) {
 
 "use strict";
 
-var contacts = jQuery("ul.contacts");
-var filterField = jQuery('<input type="search" />').insertBefore(contacts).
+var contacts = $("ul.contacts");
+var filterField = $('<input type="search" />').insertBefore(contacts).
 	on("keyup", onFilter);
 
 function onFilter(ev) {
@@ -26,4 +26,4 @@ function onFilter(ev) {
 	});
 }
 
-}());
+}(jQuery));

test/test_filtering.js

@@ -1,33 +1,40 @@
-(function() {
+(function($) {
+
+var module = QUnit.module,
+	asyncTest = QUnit.asyncTest,
+	expect = QUnit.expect,
+	strictEqual = QUnit.strictEqual,
+	deepEqual = QUnit.deepEqual,
+	start = QUnit.start;
 
 "use strict";
 
-QUnit.module("contacts filtering");
+module("contacts filtering");
 
-QUnit.asyncTest("filtering by initials", function() {
-	QUnit.expect(3);
+asyncTest("filtering by initials", function() {
+	expect(3);
 
-	var contacts = jQuery("ul.contacts");
-	var filterField = jQuery("input[type=search]");
+	var contacts = $("ul.contacts");
+	var filterField = $("input[type=search]");
 
-	QUnit.strictEqual(filterField.length, 1);
+	strictEqual(filterField.length, 1);
 	var names = extractNames(contacts.find("li:visible"));
-	QUnit.deepEqual(names, ["Jake Archibald", "Christian Heilmann",
+	deepEqual(names, ["Jake Archibald", "Christian Heilmann",
 			"John Resig", "Nicholas Zakas"]);
 
 	filterField.val("J").trigger("keyup");
 	setTimeout(function() {
 		var names = extractNames(contacts.find("li:visible"));
-		QUnit.deepEqual(names, ["Jake Archibald", "John Resig"]);
-		QUnit.start();
+		deepEqual(names, ["Jake Archibald", "John Resig"]);
+		start();
 	}, 500);
 });
 
 function extractNames(items) {
 	var names = items.map(function(i, node) {
-		return jQuery(".p-name", node).text();
+		return $(".p-name", node).text();
 	});
 	return Array.prototype.slice.call(names);
 }
 
-}());
+}(jQuery));