diff --git a/tests/gtfs/test_validation.py b/tests/gtfs/test_validation.py
index 0d698666..27797c62 100644
--- a/tests/gtfs/test_validation.py
+++ b/tests/gtfs/test_validation.py
@@ -579,6 +579,8 @@ def test__plot_summary_defences(self, gtfs_fixture):
         """Test defences for _plot_summary()."""
         current_fixture = gtfs_fixture
         current_fixture.summarise_routes()
+
+        # test parameters that are yet to be tested
         with pytest.raises(
             ValueError,
             match=re.escape(
@@ -593,6 +595,7 @@ def test__plot_summary_defences(self, gtfs_fixture):
                 orientation="l",
             )
 
+        # test the ability to make a directory
         with pytest.raises(
             NotADirectoryError,
             match=re.escape(
@@ -610,6 +613,8 @@ def test__plot_summary_on_pass(self, gtfs_fixture):
         """Test plotting a summary when defences are passed."""
         current_fixture = gtfs_fixture
         current_fixture.summarise_routes()
+
+        # test returning a html string
         test_html = gtfs_fixture._plot_summary(
             gtfs_fixture.daily_route_summary,
             "route_count_mean",
@@ -617,6 +622,7 @@ def test__plot_summary_on_pass(self, gtfs_fixture):
         )
         assert type(test_html) == str, "Failed to return HTML for the plot"
 
+        # test returning a plotly figure
         test_image = gtfs_fixture._plot_summary(
             gtfs_fixture.daily_route_summary, "route_count_mean"
         )
@@ -624,6 +630,7 @@ def test__plot_summary_on_pass(self, gtfs_fixture):
             type(test_image) == PlotlyFigure
         ), "Failed to return plotly.graph_objects.Figure type"
 
+        # test saving plots in html and png format
         gtfs_fixture._plot_summary(
             gtfs_fixture.daily_route_summary,
             "route_count_mean",
@@ -663,6 +670,7 @@ def test__plot_summary_on_pass(self, gtfs_fixture):
 
     def test__plot_route_summary_defences(self, gtfs_fixture):
         """Test the defences for the small wrapper plot_route_summary()."""
+        # test attribute checks
         with pytest.raises(
             AttributeError,
             match=(
@@ -676,6 +684,7 @@ def test__plot_route_summary_defences(self, gtfs_fixture):
 
     def test__plot_trip_summary_defences(self, gtfs_fixture):
         """Test the defences for the small wrapper plot_trip_summary()."""
+        # test attribute checks
         with pytest.raises(
             AttributeError,
             match=(