Merge pull request matplotlib#17892 from DangoMelon/earlier_color_validation

Add earlier color validation

Author: timhoffm

lib/matplotlib/cbook/__init__.py

@@ -2268,21 +2268,38 @@ def type_name(tp):
                     type_name(type(v))))
 
 
-def _check_in_list(_values, **kwargs):
+def _check_in_list(_values, *, _print_supported_values=True, **kwargs):
     """
-    For each *key, value* pair in *kwargs*, check that *value* is in *_values*;
-    if not, raise an appropriate ValueError.
+    For each *key, value* pair in *kwargs*, check that *value* is in *_values*.
+
+    Parameters
+    ----------
+    _values : iterable
+        Sequence of values to check on.
+    _print_supported_values : bool, default: True
+        Whether to print *_values* when raising ValueError.
+    **kwargs : dict
+        *key, value* pairs as keyword arguments to find in *_values*.
+
+    Raises
+    ------
+    ValueError
+        If any *value* in *kwargs* is not found in *_values*.
 
     Examples
     --------
     >>> cbook._check_in_list(["foo", "bar"], arg=arg, other_arg=other_arg)
     """
     values = _values
-    for k, v in kwargs.items():
-        if v not in values:
-            raise ValueError(
-                "{!r} is not a valid value for {}; supported values are {}"
-                .format(v, k, ', '.join(map(repr, values))))
+    for key, val in kwargs.items():
+        if val not in values:
+            if _print_supported_values:
+                raise ValueError(
+                    f"{val!r} is not a valid value for {key}; "
+                    f"supported values are {', '.join(map(repr, values))}")
+            else:
+                raise ValueError(
+                    f"{val!r} is not a valid value for {key}")
 
 
 def _check_shape(_shape, **kwargs):

lib/matplotlib/lines.py

@@ -14,6 +14,7 @@
 from .artist import Artist, allow_rasterization
 from .cbook import (
     _to_unmasked_float_array, ls_mapper, ls_mapper_r, STEP_LOOKUP_MAP)
+from .colors import is_color_like, get_named_colors_mapping
 from .markers import MarkerStyle
 from .path import Path
 from .transforms import (
@@ -1039,6 +1040,9 @@ def set_color(self, color):
         ----------
         color : color
         """
+        if not is_color_like(color) and color != 'auto':
+            cbook._check_in_list(get_named_colors_mapping(),
+                                 _print_supported_values=False, color=color)
         self._color = color
         self.stale = True
 

lib/matplotlib/tests/test_lines.py

@@ -100,6 +100,12 @@ def test_line_colors():
     fig.canvas.draw()
 
 
+def test_valid_colors():
+    line = mlines.Line2D([], [])
+    with pytest.raises(ValueError):
+        line.set_color("foobar")
+
+
 def test_linestyle_variants():
     fig = plt.figure()
     ax = fig.add_subplot(1, 1, 1)