@@ -3777,7 +3777,7 @@ function testContourfPlotData(tc)
                 "colorscale", PlotlyTestCase.Any(), ...
                 "line", struct( ...
                     "width", PlotlyTestCase.Any(), ...
-                    "color", "rgb(0,0,0)", ...
+                    "color", "rgb(217,217,217)", ...
                     "dash", PlotlyTestCase.Any(), ...
                     "smoothing", PlotlyTestCase.Any() ...
                 ), ...
@@ -3788,6 +3788,7 @@ function testContourfPlotData(tc)
                 % Octave's contour handler emits a simpler line
                 % struct and no reversescale
                 expected.line = rmfield(expected.line, {'dash', 'smoothing'});
+                expected.line.color = "rgb(0,0,0)";
                 expected = rmfield(expected, 'reversescale');
             end
             tc.verifyEqualStructs(p.data{1}, expected, 'AbsTol', 1e-15);
 
@@ -176,9 +176,9 @@ function verifyLessThan(testCase, value, ceiling, varargin)
             %-assertion's location in the test file-%
             info = '';
             st = dbstack;
-            thisFile = [mfilename('fullpath') '.m'];
+            thisFile = lower([mfilename('fullpath') '.m']);
             for i = 2:numel(st)
-                if ~isempty(st(i).file) && ~strcmp(st(i).file, thisFile)
+                if ~isempty(st(i).file) && ~strcmp(lower(st(i).file), thisFile)
                     info = sprintf('\n  at %s:%d', st(i).file, st(i).line);
                     line = PlotlyTestCase.readSourceLine(st(i).file, st(i).line);
                     if ~isempty(line)