diff --git a/tests/test_netcdf_reader.py b/tests/test_netcdf_reader.py
index 0e59b39..0335194 100644
--- a/tests/test_netcdf_reader.py
+++ b/tests/test_netcdf_reader.py
@@ -1,4 +1,3 @@
-
 import pytest
 
 from nsidc.metgen import constants
@@ -12,49 +11,87 @@
 # call them with the correct parameters, correctly handle their return values,
 # and handle any exceptions they may throw.
 
+
 @pytest.fixture
 def xdata():
     return list(range(0, 6, 2))
 
+
 @pytest.fixture
 def ydata():
     return list(range(0, 25, 5))
 
+
 @pytest.fixture
 def big_xdata():
     return list(range(0, 20, 2))
 
+
 @pytest.fixture
 def big_ydata():
     return list(range(0, 50, 5))
 
+
 def test_large_grids_are_thinned(big_xdata, big_ydata):
     result = netcdf_reader.thinned_perimeter(big_xdata, big_ydata)
     assert len(result) == (constants.DEFAULT_SPATIAL_AXIS_SIZE * 4) - 3
 
+
 def test_small_grids_are_not_thinned(xdata, ydata):
     result = netcdf_reader.thinned_perimeter(xdata, ydata)
     assert len(result) == (len(xdata) * 2) + (len(ydata) * 2) - 3
 
+
 def test_perimeter_is_closed_polygon(xdata, ydata):
     result = netcdf_reader.thinned_perimeter(xdata, ydata)
     assert result[0] == result[-1]
 
+
 def test_no_other_duplicate_values(big_xdata, big_ydata):
     result = netcdf_reader.thinned_perimeter(big_xdata, big_ydata)
     result_set = set(result)
     assert len(result_set) == len(result) - 1
 
-@pytest.mark.parametrize("input,expected", [
-    pytest.param('2001-01-01', '2001-01-01T00:00:00.000Z', id="Date and no time"),
-    pytest.param('2001-01-01 18:59:59', '2001-01-01T18:59:59.000Z', id="Date with time"),
-    pytest.param('2001-01-01 18:59.5', '2001-01-01T18:59:30.000Z', id="Datetime and fractional minutes"),
-    pytest.param('2001-01-01 18:59.500', '2001-01-01T18:59:30.000Z', id="Datetime and zero padded fractional minutes"),
-    pytest.param('2001-01-01 18:59.34', '2001-01-01T18:59:20.000Z', id="Datetime and other fractional minutes value"),
-    pytest.param('2001-01-01 18:59.999', '2001-01-01T18:59:59.000Z', id="Datetime and other fractional minutes value"),
-    pytest.param('2001-01-01 18:59:20.666', '2001-01-01T18:59:20.666Z', id="Datetime and fractional seconds"),
-    pytest.param('2001-01-01 18:59', '2001-01-01T18:59:00.000Z', id="Datetime and hours/minutes"),
-])
+
+@pytest.mark.parametrize(
+    "input,expected",
+    [
+        pytest.param("2001-01-01", "2001-01-01T00:00:00.000Z", id="Date and no time"),
+        pytest.param(
+            "2001-01-01 18:59:59", "2001-01-01T18:59:59.000Z", id="Date with time"
+        ),
+        pytest.param(
+            "2001-01-01 18:59.5",
+            "2001-01-01T18:59:30.000Z",
+            id="Datetime and fractional minutes",
+        ),
+        pytest.param(
+            "2001-01-01 18:59.500",
+            "2001-01-01T18:59:30.000Z",
+            id="Datetime and zero padded fractional minutes",
+        ),
+        pytest.param(
+            "2001-01-01 18:59.34",
+            "2001-01-01T18:59:20.000Z",
+            id="Datetime and other fractional minutes value",
+        ),
+        pytest.param(
+            "2001-01-01 18:59.999",
+            "2001-01-01T18:59:59.000Z",
+            id="Datetime and other fractional minutes value",
+        ),
+        pytest.param(
+            "2001-01-01 18:59:20.666",
+            "2001-01-01T18:59:20.666Z",
+            id="Datetime and fractional seconds",
+        ),
+        pytest.param(
+            "2001-01-01 18:59",
+            "2001-01-01T18:59:00.000Z",
+            id="Datetime and hours/minutes",
+        ),
+    ],
+)
 def test_correctly_reads_date_time_strings(input, expected):
     result = netcdf_reader.ensure_iso(input)
     assert result == expected