test(shapes,labels): add visual baselines for the outline toggle (#748)

Add PlotTester golden-baseline tests covering the render output of the
outline bool toggle: outline=True draws an outline, outline=False suppresses
it. Baselines to be generated from CI artifacts.

Author: timtreis

tests/pl/test_render_labels.py

@@ -340,6 +340,17 @@ def test_plot_can_control_label_outline(self, sdata_blobs: SpatialData):
             contour_px=15,
         ).pl.show()
 
+    def test_plot_outline_toggle_true_draws_outline(self, sdata_blobs: SpatialData):
+        # #748: outline=True is a shortcut for outline_alpha=1 (must draw a contour).
+        sdata_blobs.pl.render_labels("blobs_labels", outline=True, fill_alpha=0.0, contour_px=15).pl.show()
+
+    def test_plot_outline_toggle_false_suppresses_outline(self, sdata_blobs: SpatialData):
+        # #748: outline=False wins over the outline_* params (no contour drawn).
+        with pytest.warns(UserWarning, match="outline=False"):
+            sdata_blobs.pl.render_labels(
+                "blobs_labels", outline=False, outline_color="red", outline_alpha=1.0, contour_px=15
+            ).pl.show()
+
     def test_plot_can_control_label_infill(self, sdata_blobs: SpatialData):
         sdata_blobs.pl.render_labels(
             "blobs_labels",

tests/pl/test_render_shapes.py

@@ -108,6 +108,17 @@ def test_plot_can_render_polygons(self, sdata_blobs: SpatialData):
     def test_plot_can_render_polygons_with_outline(self, sdata_blobs: SpatialData):
         sdata_blobs.pl.render_shapes(element="blobs_polygons", outline_alpha=1).pl.show()
 
+    def test_plot_outline_toggle_true_draws_outline(self, sdata_blobs: SpatialData):
+        # #748: outline=True is a shortcut for outline_alpha=1 (must draw an outline).
+        sdata_blobs.pl.render_shapes(element="blobs_polygons", outline=True).pl.show()
+
+    def test_plot_outline_toggle_false_suppresses_outline(self, sdata_blobs: SpatialData):
+        # #748: outline=False wins over the outline_* params (no outline drawn).
+        with pytest.warns(UserWarning, match="outline=False"):
+            sdata_blobs.pl.render_shapes(
+                element="blobs_polygons", outline=False, outline_color="red", outline_alpha=1
+            ).pl.show()
+
     def test_plot_can_render_polygons_with_str_colored_outline(self, sdata_blobs: SpatialData):
         sdata_blobs.pl.render_shapes(element="blobs_polygons", outline_alpha=1, outline_color="red").pl.show()