--- a/tests/test_viewer.py	Mon Sep 18 16:54:55 2017 +0800
+++ b/tests/test_viewer.py	Mon Sep 18 17:07:32 2017 +0800
@@ -11,6 +11,12 @@
 from viewer import CandolintViewer
 
 
+XMLNS = {
+    'atom': 'http://www.w3.org/2005/Atom',
+    'svg': 'http://www.w3.org/2000/svg'
+}
+
+
 def setup_module():
     with database.transaction():
         project = Project.create(
@@ -127,12 +133,12 @@
         assert response.code == 200
         assert 'atom+xml' in response.headers['Content-Type']
         root = ElementTree.fromstring(response.body)
-        ns = {'atom': 'http://www.w3.org/2005/Atom'}
-        title = root.find('./atom:entry/atom:title', ns)
+        assert root.tag == '{%s}%s' % (XMLNS['atom'], 'feed')
+        title = root.find('./atom:entry/atom:title', XMLNS)
         assert title is not None
         assert title.text.startswith('Check #')
         assert title.text.endswith(' 1 error, 1 warning')
-        updates = [el.text for el in root.findall('.//atom:updated', ns)]
+        updates = [el.text for el in root.findall('.//atom:updated', XMLNS)]
         assert len(updates) == min(Check.select().count(), 20) + 1
         assert updates[0] == updates[1] == '2016-08-20T02:38:53Z'
 
@@ -179,19 +185,17 @@
         response = self.fetch('/example.com/alice/test-viewer/status.svg')
         assert response.code == 200
         root = ElementTree.fromstring(response.body)
-        ns = {'svg': 'http://www.w3.org/2000/svg'}
-        assert root.tag == '{http://www.w3.org/2000/svg}svg'
+        assert root.tag == '{%s}%s' % (XMLNS['svg'], 'svg')
         assert root.attrib.get('height') == '20'
-        text = [el.text for el in root.findall('./svg:g/svg:text', ns)]
+        text = [el.text for el in root.findall('./svg:g/svg:text', XMLNS)]
         assert text[::2] == ['lint', '1 error', '1 warning']
 
     def test_dot(self):
         response = self.fetch('/example.com/alice/test-viewer/latest/dot.svg')
         assert response.code == 200
         root = ElementTree.fromstring(response.body)
-        ns = {'svg': 'http://www.w3.org/2000/svg'}
-        assert root.tag == '{http://www.w3.org/2000/svg}svg'
+        assert root.tag == '{%s}%s' % (XMLNS['svg'], 'svg')
         assert root.attrib.get('height') == '12'
-        circles = root.findall('./svg:circle', ns)
+        circles = root.findall('./svg:circle', XMLNS)
         assert len(circles) == 1
         assert circles[0].attrib.get('fill').startswith('#')