Resolve a few TODOs related to Python 3.6

openmc/data/library.py

@@ -146,10 +146,6 @@ class DataLibrary(EqualityMixin):
             raise ValueError("Either path or OPENMC_CROSS_SECTIONS "
                              "environmental variable must be set")
 
-        # Convert to string to support pathlib
-        # TODO: Remove when support is Python 3.6+ only
-        path = str(path)
-
         tree = ET.parse(path)
         root = tree.getroot()
         if root.find('directory') is not None:

openmc/deplete/abc.py

@@ -158,11 +158,8 @@ class TransportOperator(ABC):
     def __enter__(self):
         # Save current directory and move to specific output directory
         self._orig_dir = os.getcwd()
-        if not self.output_dir.exists():
-            self.output_dir.mkdir()  # exist_ok parameter is 3.5+
-
-        # In Python 3.6+, chdir accepts a Path directly
-        os.chdir(str(self.output_dir))
+        self.output_dir.mkdir(exist_ok=True)
+        os.chdir(self.output_dir)
 
         return self.initial_condition()
 

tests/regression_tests/mgxs_library_distribcell/test.py

@@ -68,8 +68,6 @@ class MGXSTestHarness(PyAPITestHarness):
         return outstr
 
 
-@pytest.mark.xfail(sys.version_info < (3, 6),
-                   reason="Pandas 1.0 API changed and requires Python 3.6+")
 def test_mgxs_library_distribcell():
     model = pwr_assembly()
     harness = MGXSTestHarness('statepoint.10.h5', model)

tests/unit_tests/test_deplete_fission_yields.py

@@ -43,12 +43,11 @@ def materials(tmpdir_factory):
         with lib.run_in_memory():
             yield [lib.Material(), lib.Material()]
     finally:
-        # Convert to strings as os.remove in py 3.5 doesn't support Paths
         for file_path in ("settings.xml", "geometry.xml", "materials.xml",
                           "summary.h5"):
-            os.remove(str(tmpdir / file_path))
+            os.remove(tmpdir / file_path)
         orig.chdir()
-        os.rmdir(str(tmpdir))
+        os.rmdir(tmpdir)
 
 
 def proxy_tally_data(tally, fill=None):