treewide: migrate to pythonPackages.unittestCheckHook

pkgs/development/python2-modules/mock/default.nix

@@ -5,7 +5,7 @@
 , funcsigs
 , six
 , pbr
-, python
+, unittestCheckHook
 , pytest
 }:
 
@@ -27,11 +27,8 @@ buildPythonPackage rec {
   #doCheck = !(python.isPyPy && python.isPy27);
   doCheck = false; # Infinite recursion pytest
 
-  checkPhase = ''
-    ${python.interpreter} -m unittest discover
-  '';
-
   checkInputs = [
+    unittestCheckHook
     pytest
   ];
 

pkgs/development/python2-modules/typing/default.nix

@@ -1,4 +1,4 @@
-{ lib, buildPythonPackage, fetchPypi, pythonOlder, isPy3k, isPyPy, python
+{ lib, buildPythonPackage, fetchPypi, pythonOlder, isPy3k, isPyPy, unittestCheckHook
 , pythonAtLeast }:
 
 let
@@ -20,10 +20,9 @@ in buildPythonPackage rec {
   # Also, don't bother on PyPy: AssertionError: TypeError not raised
   doCheck = pythonOlder "3.6" && !isPyPy;
 
-  checkPhase = ''
-    cd ${testDir}
-    ${python.interpreter} -m unittest discover
-  '';
+  checkInputs = [ unittestCheckHook ];
+
+  unittestFlagsArray = [ "-s" testDir ];
 
   meta = with lib; {
     description = "Backport of typing module to Python versions older than 3.5";