Merge pull request matplotlib#25891 from turnipseason/add-tests-for-nargs-err

Adds tests for nargs_err in legend, stem, pcolorfast and cycler.

Author: oscargus

lib/matplotlib/tests/test_axes.py

@@ -662,6 +662,28 @@ def test_sticky_shared_axes(fig_test, fig_ref):
     ax0.pcolormesh(Z)
 
 
+def test_nargs_stem():
+    with pytest.raises(TypeError, match='0 were given'):
+        # stem() takes 1-3 arguments.
+        plt.stem()
+
+
+def test_nargs_legend():
+    with pytest.raises(TypeError, match='3 were given'):
+        ax = plt.subplot()
+        # legend() takes 0-2 arguments.
+        ax.legend(['First'], ['Second'], 3)
+
+
+def test_nargs_pcolorfast():
+    with pytest.raises(TypeError, match='2 were given'):
+        ax = plt.subplot()
+        # pcolorfast() takes 1 or 3 arguments,
+        # not passing any arguments fails at C = args[-1]
+        # before nargs_err is raised.
+        ax.pcolorfast([(0, 1), (0, 2)], [[1, 2, 3], [1, 2, 3]])
+
+
 @image_comparison(['offset_points'], remove_text=True)
 def test_basic_annotate():
     # Setup some data

lib/matplotlib/tests/test_rcparams.py

@@ -118,6 +118,13 @@ def test_rcparams_init():
         mpl.RcParams({'figure.figsize': (3.5, 42, 1)})
 
 
+def test_nargs_cycler():
+    from matplotlib.rcsetup import cycler as ccl
+    with pytest.raises(TypeError, match='3 were given'):
+        # cycler() takes 0-2 arguments.
+        ccl(ccl(color=list('rgb')), 2, 3)
+
+
 def test_Bug_2543():
     # Test that it possible to add all values to itself / deepcopy
     # https://github.com/matplotlib/matplotlib/issues/2543