TST: test negative clevs BoundaryNorm

jklymak · jklymak · commit c71cf0895cda · 2021-11-19T07:25:38.000+01:00
diff --git a/lib/matplotlib/tests/test_colorbar.py b/lib/matplotlib/tests/test_colorbar.py
@@ -873,3 +873,24 @@ def test_proportional_colorbars():
             CS3 = axs[i, j].contourf(X, Y, Z, levels, cmap=cmap, norm=norm,
                                      extend=extends[i])
             fig.colorbar(CS3, spacing=spacings[j], ax=axs[i, j])
+
+
+def test_negative_boundarynorm():
+    fig, ax = plt.subplots(figsize=(1, 3))
+    cmap = plt.get_cmap("viridis")
+    clevs = np.arange(-94, -85)
+    norm = BoundaryNorm(clevs, cmap.N)
+    cb = fig.colorbar(cm.ScalarMappable(cmap=cmap, norm=norm), cax=ax)
+    np.testing.assert_allclose(cb.ax.get_ylim(), [clevs[0], clevs[-1]])
+    np.testing.assert_allclose(cb.ax.get_yticks(), clevs)
+    clevs = np.arange(85, 94)
+    norm = BoundaryNorm(clevs, cmap.N)
+    cb = fig.colorbar(cm.ScalarMappable(cmap=cmap, norm=norm), cax=ax)
+    np.testing.assert_allclose(cb.ax.get_ylim(), [clevs[0], clevs[-1]])
+    np.testing.assert_allclose(cb.ax.get_yticks(), clevs)
+
+    clevs = np.arange(-3, 3)
+    norm = BoundaryNorm(clevs, cmap.N)
+    cb = fig.colorbar(cm.ScalarMappable(cmap=cmap, norm=norm), cax=ax)
+    np.testing.assert_allclose(cb.ax.get_ylim(), [clevs[0], clevs[-1]])
+    np.testing.assert_allclose(cb.ax.get_yticks(), clevs)
