Tests that describing a table's schema returns the correct column meta-information.

Source

						public function testDescribe() {
		$result = $this->db->describe('companies');
		$expected = array(
			'id' => array('type' => 'integer', 'length' => 11, 'null' => false, 'default' => null),
			'name' => array('type' => 'string', 'length' => 255, 'null' => true, 'default' => null),
			'active' => array('type' => 'boolean', 'null' => true, 'default' => null),
			'created' => array('type' => 'datetime', 'null' => true, 'default' => null),
			'modified' => array('type' => 'datetime', 'null' => true, 'default' => null)
		);
		$this->assertEqual($expected, $result);
	}