Added unit test to verify axes limits in Axes.fill_between

Author: olinjohnson

lib/matplotlib/tests/test_axes.py

@@ -8558,3 +8558,19 @@ def test_ecdf_invalid():
         plt.ecdf([1, np.nan])
     with pytest.raises(ValueError):
         plt.ecdf(np.ma.array([1, 2], mask=[True, False]))
+
+
+def test_fill_between_axes_limits():
+    fig, ax = plt.subplots()
+    x = np.arange(0, 4 * np.pi, 0.01)
+    y = 0.1*np.sin(x)
+    threshold = 0.075
+    ax.plot(x, y, color='black')
+
+    original_lims = (ax.get_xlim(), ax.get_ylim())
+
+    ax.axhline(threshold, color='green', lw=2, alpha=0.7)
+    ax.fill_between(x, 0, 1, where=y > threshold,
+                    color='green', alpha=0.5, transform=ax.get_xaxis_transform())
+
+    assert (ax.get_xlim(), ax.get_ylim()) == original_lims