python3Packages.django-auth-ldap: fix build

Add additional hints to get tests going, but they're still failing with
missing LDAP schemas somewhere.

pkgs/development/python-modules/django-auth-ldap/default.nix

@@ -2,30 +2,50 @@
 , buildPythonPackage
 , fetchPypi
 , isPy27
+
+# buildtime
+, setuptools-scm
+
+# runtime
 , ldap
 , django
-, mock
-, setuptools-scm
+
+# tests
+, python
+, pkgs
 }:
 
 buildPythonPackage rec {
   pname = "django-auth-ldap";
   version = "4.0.0";
+  format = "pyproject";
+
   disabled = isPy27;
+
   src = fetchPypi {
     inherit pname version;
     sha256 = "276f79e624ce083ce13f161387f65ff1c0efe83ef8a42f2b9830d43317b15239";
   };
 
-  nativeBuildInputs = [ setuptools-scm ];
+  nativeBuildInputs = [
+    setuptools-scm
+  ];
 
-  propagatedBuildInputs = [ ldap django ];
+  propagatedBuildInputs = [
+    django
+    ldap
+  ];
 
-  checkInputs = [ mock ];
-
-  # django.core.exceptions.ImproperlyConfigured: Requested setting INSTALLED_APPS, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings
+  # ValueError: SCHEMADIR is None, ldap schemas are missing.
   doCheck = false;
 
+  checkPhase = ''
+    runHook preCheck
+    export PATH=${pkgs.openldap}/bin:${pkgs.openldap}/libexec:$PATH
+    ${python.interpreter} -m django test --settings tests.settings
+    runHook postCheck
+  '';
+
   pythonImportsCheck = [ "django_auth_ldap" ];
 
   meta = with lib; {