python3Packages.periodictable: fix tests

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

@@ -1,4 +1,4 @@
-{lib, fetchPypi, buildPythonPackage, numpy, pyparsing}:
+{lib, fetchPypi, buildPythonPackage, numpy, pyparsing, pytestcov, pytestCheckHook }:
 
 buildPythonPackage rec {
   pname = "periodictable";
@@ -11,6 +11,8 @@ buildPythonPackage rec {
     sha256 = "1d09c359468e2de74b43fc3a7dcb0d3d71e0ff53adb85995215d8d7796451af6";
   };
 
+  checkInputs = [ pytestcov pytestCheckHook ];
+
   meta = {
     homepage = "https://www.reflectometry.org/danse/software.html";
     description = "an extensible periodic table of the elements prepopulated with data important to neutron and x-ray scattering experiments";