Add test of clabel with large padding

Author: ksunden

lib/matplotlib/tests/test_contour.py

@@ -338,6 +338,22 @@ def test_clabel_zorder(use_clabeltext, contour_zorder, clabel_zorder):
         assert clabel.get_zorder() == expected_clabel_zorder
 
 
+def test_clabel_with_large_spacing():
+    # When the inline spacing is large relative to the contour, it may cause the
+    # entire contour to be removed. In current implementation, one line segment is
+    # retained between the identified points.
+    # This behavior may be worth reconsidering, but check to be sure we do not produce
+    # an invalid path, which results in an error at clabel call time.
+    # see gh-27045 for more information
+    x = y = np.arange(-3.0, 3.01, 0.05)
+    X, Y = np.meshgrid(x, y)
+    Z = np.exp(-X**2 - Y**2)
+
+    fig, ax = plt.subplots()
+    contourset = ax.contour(X, Y, Z, levels=[0.01, 0.2, .5, .8])
+    ax.clabel(contourset, inline_spacing=100)
+
+
 # tol because ticks happen to fall on pixel boundaries so small
 # floating point changes in tick location flip which pixel gets
 # the tick.