diff -r a570191d67b0 -r 2fcb53ee5178 cubicweb/test/unittest_binary.py
--- a/cubicweb/test/unittest_binary.py	Tue Oct 09 16:24:12 2018 +0200
+++ b/cubicweb/test/unittest_binary.py	Mon Oct 29 10:04:31 2018 +0100
@@ -33,7 +33,7 @@
         Binary(b'toto')
         Binary(bytearray(b'toto'))
         if PY2:
-            Binary(buffer('toto'))
+            Binary(buffer('toto'))  # noqa: F821
         else:
             Binary(memoryview(b'toto'))
         with self.assertRaises((AssertionError, TypeError)):
@@ -45,7 +45,7 @@
         b.write(b'toto')
         b.write(bytearray(b'toto'))
         if PY2:
-            b.write(buffer('toto'))
+            b.write(buffer('toto'))  # noqa: F821
         else:
             b.write(memoryview(b'toto'))
         with self.assertRaises((AssertionError, TypeError)):