added loopcontrols extension and added unittests for it

--HG--
branch : trunk
diff --git a/tests/test_ext.py b/tests/test_ext.py
new file mode 100644
index 0000000..5a487cf
--- /dev/null
+++ b/tests/test_ext.py
@@ -0,0 +1,37 @@
+# -*- coding: utf-8 -*-
+"""
+    unit test for some extensions
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    :copyright: 2008 by Armin Ronacher.
+    :license: BSD, see LICENSE for more details.
+"""
+from jinja2 import Environment
+
+
+def test_loop_controls():
+    env = Environment(extensions=['jinja2.ext.loopcontrols'])
+
+    tmpl = env.from_string('''
+        {%- for item in [1, 2, 3, 4] %}
+            {%- if item % 2 == 0 %}{% continue %}{% endif -%}
+            {{ item }}
+        {%- endfor %}''')
+    assert tmpl.render() == '13'
+
+    tmpl = env.from_string('''
+        {%- for item in [1, 2, 3, 4] %}
+            {%- if item > 2 %}{% break %}{% endif -%}
+            {{ item }}
+        {%- endfor %}''')
+    assert tmpl.render() == '12'
+
+
+def test_do():
+    env = Environment(extensions=['jinja2.ext.do'])
+    tmpl = env.from_string('''
+        {%- set items = [] %}
+        {%- for char in "foo" %}
+            {%- do items.append(loop.index0 ~ char) %}
+        {%- endfor %}{{ items|join(', ') }}''')
+    assert tmpl.render() == '0f, 1o, 2o'