pythonPackages.pytest-virtualenv: Move to own file

pkgs/development/python-modules/pytest-virtualenv/default.nix

@@ -0,0 +1,23 @@
+{ stdenv, buildPythonPackage, fetchPypi
+, pytest, pytestcov, mock, cmdline, pytest-fixture-config, pytest-shutil }:
+
+buildPythonPackage rec {
+  pname = "pytest-virtualenv";
+  version = "1.2.7";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "0mb76zhlak4qjjq2h7kaxbihk1b9plmimbzcb8qv4906cxl69ysi";
+  };
+
+  buildInputs = [ pytest pytestcov mock cmdline ];
+  propagatedBuildInputs = [ pytest-fixture-config pytest-shutil ];
+  checkPhase = '' py.test tests/unit '';
+
+  meta = with stdenv.lib; {
+    description = "Create a Python virtual environment in your test that cleans up on teardown. The fixture has utility methods to install packages and list what’s installed.";
+    homepage = https://github.com/manahl/pytest-plugins;
+    license = licenses.mit;
+    maintainers = with maintainers; [ ryansydnor ];
+  };
+}