pythonPackages.regex: fix darwin build

The package works fine on darwin. We run some tests to prove this.

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

@@ -1,6 +1,7 @@
 { lib
 , buildPythonPackage
 , fetchPypi
+, python
 }:
 
 
@@ -13,11 +14,15 @@ buildPythonPackage rec {
     sha256 = "2353c0e983c4029caf32016f1dddef623c3117ac282a818468c6d2f5d541698d";
   };
 
+  postCheck = ''
+    echo "We now run tests ourselves, since the setuptools installer doesn't."
+    ${python.interpreter} -c 'import test_regex; test_regex.test_main();'
+  '';
+
   meta = {
     description = "Alternative regular expression module, to replace re";
     homepage = https://bitbucket.org/mrabarnett/mrab-regex;
     license = lib.licenses.psfl;
-    platforms = lib.platforms.linux;
     maintainers = with lib.maintainers; [ abbradar ];
   };
 }