pythonPackages.django_taggit: fix build, enable tests

pkgs/development/python-modules/django_taggit/default.nix

@@ -1,7 +1,11 @@
 { stdenv
 , buildPythonPackage
+, python
 , fetchPypi
 , pythonOlder
+, django
+, mock
+, isort
 }:
 
 buildPythonPackage rec {
@@ -14,7 +18,14 @@ buildPythonPackage rec {
     sha256 = "a21cbe7e0879f1364eef1c88a2eda89d593bf000ebf51c3f00423c6927075dce";
   };
 
-  doCheck = false;
+  propagatedBuildInputs = [ isort django ];
+
+  checkInputs = [ mock ];
+  checkPhase = ''
+    # prove we're running tests against installed package, not build dir
+    rm -r taggit
+    ${python.interpreter} -m django test --settings=tests.settings
+  '';
 
   meta = with stdenv.lib; {
     description = "django-taggit is a reusable Django application for simple tagging";