use figure-equality tests for zero-width dashed rendering

francisayyad03 · francisayyad03 · commit 0fe9994aa85a · 2026-03-16T13:15:43.000-04:00
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -8081,17 +8081,19 @@ def test_twinning_default_axes_class():
     assert type(twiny) is Axes
 
 
-def test_zero_linewidth():
-    # Check that setting a zero linewidth doesn't error
-    plt.plot([0, 1], [0, 1], ls='--', lw=0)
-    plt.gcf().canvas.draw()
+@check_figures_equal()
+def test_zero_linewidth(fig_test, fig_ref):
+    fig_test.subplots().plot([0, 1], [0, 1], ls='--', lw=0)
+    fig_ref.subplots().plot([0, 1], [0, 1], ls='-', lw=0)
 
 
 @mpl.style.context('mpl20')
-def test_stairs_fill_zero_linewidth():
-    fig, ax = plt.subplots()
-    ax.stairs([1, 2, 3, 4], [1, 2, 3, 4, 5], fill=True, ls='--')
-    fig.canvas.draw()
+@check_figures_equal()
+def test_stairs_fill_zero_linewidth(fig_test, fig_ref):
+    fig_test.subplots().stairs(
+        [1, 2, 3, 4], [1, 2, 3, 4, 5], fill=True, ls='--')
+    fig_ref.subplots().stairs(
+        [1, 2, 3, 4], [1, 2, 3, 4, 5], fill=True, ls='-')
 
 
 def test_empty_errorbar_legend():
diff --git a/lib/matplotlib/tests/test_patches.py b/lib/matplotlib/tests/test_patches.py
@@ -907,10 +907,12 @@ def test_default_linestyle():
     assert patch.get_linestyle() == 'solid'
 
 
-def test_patch_zero_linewidth_dashed_draw():
-    fig, ax = plt.subplots()
-    ax.add_patch(Rectangle((0, 0), 1, 1, fill=False, linewidth=0, linestyle='--'))
-    fig.canvas.draw()
+@check_figures_equal()
+def test_patch_zero_linewidth_dashed_draw(fig_test, fig_ref):
+    fig_test.subplots().add_patch(
+        Rectangle((0, 0), 1, 1, fill=False, linewidth=0, linestyle='--'))
+    fig_ref.subplots().add_patch(
+        Rectangle((0, 0), 1, 1, fill=False, linewidth=0, linestyle='-'))
 
 
 def test_default_capstyle():
