fix fn.closest() and add context argument

old implementation started from the parent, while the correct
implementation should start from the current element

README.rdoc

@@ -47,7 +47,7 @@ Context and .find calls are equivalent:
   last(): new collection containing only the last matched element
 
   find('selector'): find all children/grandchildren that match the given selector
-  closest('selector'): traverses the DOM upwards to find the first matching element
+  closest('selector'): find the first matching element by going upwards starting from the current element
   next(): next siblings
   prev(): previous siblings
   is('selector'): returns true/false if first element matches the selector

src/zepto.js

@@ -66,10 +66,11 @@ var Zepto = (function() {
     find: function(selector){
       return $(this.dom.map(function(el){ return $$(el, selector) }).reduce(function(a,b){ return a.concat(b) }, []));
     },
-    closest: function(selector){
-      var node = this.dom[0].parentNode, nodes = $$(document, selector);
-      while(node && nodes.indexOf(node) < 0) node = node.parentNode;
-      return $(node && !(node === document) ? node : []);
+    closest: function(selector, context){
+      var node = this.dom[0], nodes = $$(context !== undefined ? context : document, selector);
+      if (nodes.length === 0) node = null;
+      while(node && node !== document && nodes.indexOf(node) < 0) node = node.parentNode;
+      return $(node);
     },
     pluck: function(property){ return this.dom.map(function(element){ return element[property] }) },
     show: function(){ return this.css('display', 'block') },

test/zepto.html

@@ -51,10 +51,12 @@ <h1>Zepto DOM unit tests</h1>
 
   <div style="position:absolute;width:100px;height:50px" id="offset">test</div>
 
-  <ul>
+  <ul id="parents">
     <li id="li1">
-      <ul>
-        <li id="li2">
+      <ul id="nested">
+        <li id="li2">one</li>
+        <li>two</li>
+        <li>three</li>
       </ul>
     </li>
   </ul>
@@ -121,6 +123,16 @@ <h1>Zepto DOM unit tests</h1>
         'Expected length %d, got %d.', expected, actual);
     }
 
+    Evidence.Assertions.assertEqualCollection = function(expectedCollection, actualCollection, message) {
+      var expected = expectedCollection.get(), actual = actualCollection.get(),
+          passed = expected.length == actual.length;
+
+      if (passed) for (var i=0; i<expected.length; i++) passed = expected[i] == actual[i];
+
+      this._assertExpression(passed, message || 'Failed assertion.',
+        'Expected %o, got %o.', expected, actual);
+    }
+
     Evidence.TestCase.extend('ZeptoTest', {
 
       // test to see if we augment iOS 3.2 with String#trim()
@@ -320,8 +332,14 @@ <h1>Zepto DOM unit tests</h1>
       },
 
       testClosest: function(t){
-        t.assertIdentical($('#li1').get(0), $('#li2').closest('li').get(0));
-        t.assertLength(0, $('#li2').closest('div'));
+        var el = $('#li2');
+        t.assertEqualCollection(el, el.closest('li'));
+        t.assertEqualCollection($('#nested'), el.closest('ul'));
+        // with context
+        t.assertEqualCollection($('#nested'), el.closest('ul', $('#li1').get(0)));
+        t.assertLength(0, el.closest('#parents', $('#li1').get(0)));
+        // no ancestor matched
+        t.assertLength(0, el.closest('div'));
       },
 
       testFind: function(t){