Oops

default.nix

@@ -7,6 +7,8 @@ pkgs.python3Packages.buildPythonPackage rec {
   src = ./.; # location of setup.py
 
   checkPhase = ''
+    runHook preCheck
     ${pkgs.python3}/bin/python -m unittest test.run_tests
+    runHook postCheck
   '';
 }