add tests for pts_to_pre/mid/poststep() with empty args

timhoffm · timhoffm · commit cd250ac4fd5c · 2017-12-17T18:48:27.000+01:00
diff --git a/lib/matplotlib/cbook/__init__.py b/lib/matplotlib/cbook/__init__.py
@@ -2167,7 +2167,7 @@ def pts_to_prestep(x, *args):
     Parameters
     ----------
     x : array
-        The x location of the steps.
+        The x location of the steps. May be empty.
 
     y1, ..., yp : array
         y arrays to be turned into steps; all must be the same length as ``x``.
@@ -2177,7 +2177,8 @@ def pts_to_prestep(x, *args):
     out : array
         The x and y values converted to steps in the same order as the input;
         can be unpacked as ``x_out, y1_out, ..., yp_out``.  If the input is
-        length ``N``, each of these arrays will be length ``2N + 1``.
+        length ``N``, each of these arrays will be length ``2N + 1``. For
+        ``N=0``, the length will be 0.
 
     Examples
     --------
@@ -2204,7 +2205,7 @@ def pts_to_poststep(x, *args):
     Parameters
     ----------
     x : array
-        The x location of the steps.
+        The x location of the steps. May be empty.
 
     y1, ..., yp : array
         y arrays to be turned into steps; all must be the same length as ``x``.
@@ -2214,7 +2215,8 @@ def pts_to_poststep(x, *args):
     out : array
         The x and y values converted to steps in the same order as the input;
         can be unpacked as ``x_out, y1_out, ..., yp_out``.  If the input is
-        length ``N``, each of these arrays will be length ``2N + 1``.
+        length ``N``, each of these arrays will be length ``2N + 1``. For
+        ``N=0``, the length will be 0.
 
     Examples
     --------
@@ -2239,7 +2241,7 @@ def pts_to_midstep(x, *args):
     Parameters
     ----------
     x : array
-        The x location of the steps.
+        The x location of the steps. May be empty.
 
     y1, ..., yp : array
         y arrays to be turned into steps; all must be the same length as ``x``.
diff --git a/lib/matplotlib/tests/test_cbook.py b/lib/matplotlib/tests/test_cbook.py
@@ -392,6 +392,11 @@ def test_to_prestep():
     assert_array_equal(y1_target, y1s)
 
 
+def test_to_prestep_empty():
+    steps = cbook.pts_to_prestep([], [])
+    assert steps.shape == (2, 0)
+
+
 def test_to_poststep():
     x = np.arange(4)
     y1 = np.arange(4)
@@ -412,6 +417,11 @@ def test_to_poststep():
     assert_array_equal(y1_target, y1s)
 
 
+def test_to_poststep_empty():
+    steps = cbook.pts_to_poststep([], [])
+    assert steps.shape == (2, 0)
+
+
 def test_to_midstep():
     x = np.arange(4)
     y1 = np.arange(4)
@@ -432,6 +442,11 @@ def test_to_midstep():
     assert_array_equal(y1_target, y1s)
 
 
+def test_to_midstep_empty():
+    steps = cbook.pts_to_midstep([], [])
+    assert steps.shape == (2, 0)
+
+
 @pytest.mark.parametrize(
     "args",
     [(np.arange(12).reshape(3, 4), 'a'),
