Lets see if this works for phongo...

tests/CollectionTest.php

+<?php
+class CollectionTest extends PHPUnit_Framework_TestCase
+{
+    public function testPushAndPop()
+    {
+        $stack = array();
+        $this->assertEquals(0, count($stack));
+
+        array_push($stack, 'foo');
+        $this->assertEquals('foo', $stack[count($stack)-1]);
+        $this->assertEquals(1, count($stack));
+
+        $this->assertEquals('foo', array_pop($stack));
+        $this->assertEquals(0, count($stack));
+    }
+}
+