python.pkgs.jinja2: enable tests

pkgs/development/python-modules/jinja2/default.nix

@@ -1,20 +1,24 @@
-{ stdenv, buildPythonPackage, fetchPypi
-, markupsafe }:
+{ stdenv, buildPythonPackage, fetchFromGitHub
+, pytest, markupsafe }:
 
 buildPythonPackage rec {
   pname = "Jinja2";
   version = "2.9.6";
   name = "${pname}-${version}";
 
-  src = fetchPypi {
-    inherit pname version;
-    sha256 = "1zzrkywhziqffrzks14kzixz7nd4yh2vc0fb04a68vfd2ai03anx";
+  src = fetchFromGitHub {
+    owner = "pallets";
+    repo = "jinja";
+    rev = version;
+    sha256 = "1xxc5vdhz214aawmllv0fi4ak6d7zac662yb7gn1xfgqfz392pg5";
   };
 
+  checkInputs = [ pytest ];
   propagatedBuildInputs = [ markupsafe ];
 
-  # No tests included
-  doCheck = false;
+  checkPhase = ''
+    pytest -v
+  '';
 
   meta = with stdenv.lib; {
     homepage = http://jinja.pocoo.org/;
@@ -24,7 +28,7 @@ buildPythonPackage rec {
       Jinja2 is a template engine written in pure Python. It provides a
       Django inspired non-XML syntax but supports inline expressions and
       an optional sandboxed environment.
-      '';
+    '';
     platforms = platforms.all;
     maintainers = with maintainers; [ pierron garbas sjourdois ];
   };