Add unit tests.

test/unit/fixtures/selector_engine.html

@@ -0,0 +1,4 @@
+<div id="test_div_parent" class="test_class">
+  <div id="test_div_child" class="test_class">
+  </div>
+</div>

test/unit/selector_engine_test.js

@@ -0,0 +1,53 @@
+/*
+<div id="test_div_parent" class="test_class">
+  <div id="test_div_child" class="test_class">
+  </div>
+</div>
+*/
+
+new Test.Unit.Runner({
+  testEngine: function() {
+    this.assert(Prototype.Selector.engine);
+  },
+  
+  testSelect: function() {
+    var elements = Prototype.Selector.select('.test_class');
+    
+    this.assert(Object.isArray(elements));
+    this.assertEqual(2, elements.length);
+    this.assertEqual('test_div_parent', elements[0].id);
+    this.assertEqual('test_div_child', elements[1].id);
+  },
+  
+  testSelectWithContext: function() {
+    var elements = Prototype.Selector.select('.test_class', $('test_div_parent'));
+    
+    this.assert(Object.isArray(elements));
+    this.assertEqual(1, elements.length);
+    this.assertEqual('test_div_child', elements[0].id);
+  },
+  
+  testSelectWithEmptyResult: function() {
+    var elements = Prototype.Selector.select('.non_existent');
+    
+    this.assert(Object.isArray(elements));
+    this.assertEqual(0, elements.length);
+  },
+  
+  testMatch: function() {
+    var element = $('test_div_parent');
+    
+    this.assertEqual(true, Prototype.Selector.match(element, '.test_class'));
+    this.assertEqual(false, Prototype.Selector.match(element, '.non_existent'));
+  },
+  
+  testFilter: function() {
+    var elements = document.getElementsByTagName('*'),
+        filtered = Prototype.Selector.filter(elements, '.test_class');
+        
+    this.assert(Object.isArray(filtered));
+    this.assertEqual(2, filtered.length);
+    this.assertEqual('test_div_parent', filtered[0].id);
+    this.assertEqual('test_div_child', filtered[1].id);
+  }
+});