adds jinja2 filters support (#41)

* adds jinja2 filters support

* removes redundant filter value check

aiohttp_jinja2/__init__.py

@@ -16,8 +16,10 @@
 APP_CONTEXT_PROCESSORS_KEY = 'aiohttp_jinja2_context_processors'
 
 
-def setup(app, *args, app_key=APP_KEY, context_processors=(), **kwargs):
+def setup(app, *args, app_key=APP_KEY, context_processors=(), filters=None, **kwargs):
     env = jinja2.Environment(*args, **kwargs)
+    if filters is not None:
+        env.filters.update(filters)
     app[app_key] = env
     if context_processors:
         app[APP_CONTEXT_PROCESSORS_KEY] = context_processors

tests/test_jinja_filters.py

@@ -0,0 +1,31 @@
+import aiohttp
+import aiohttp_jinja2
+import asyncio
+import jinja2
+import pytest
+
+
+@pytest.mark.run_loop
+def test_jinja_filters(create_server, loop):
+
+    @aiohttp_jinja2.template('tmpl.jinja2')
+    @asyncio.coroutine
+    def index(request):
+        return {}
+
+    def add_2(value):
+        return value + 2
+
+    app, url = yield from create_server()
+    aiohttp_jinja2.setup(
+        app,
+        loader=jinja2.DictLoader({'tmpl.jinja2': "{{ 5|add_2 }}"}),
+        filters={'add_2': add_2}
+    )
+
+    app.router.add_route('GET', '/', index)
+
+    resp = yield from aiohttp.request('GET', url, loop=loop)
+    assert 200 == resp.status
+    txt = yield from resp.text()
+    assert '7' == txt