matplotlib · timhoffm · Apr 7, 2022 · Mar 30, 2022
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -169,25 +169,25 @@ def _process_plot_format(fmt):
         if fmt[i:i+2] in mlines.lineStyles:  # First, the two-char styles.
             if linestyle is not None:
                 raise ValueError(
-                    'Illegal format string "%s"; two linestyle symbols' % fmt)
+                    f'Illegal format string {fmt!r}; two linestyle symbols')
             linestyle = fmt[i:i+2]
             i += 2
         elif c in mlines.lineStyles:
             if linestyle is not None:
                 raise ValueError(
-                    'Illegal format string "%s"; two linestyle symbols' % fmt)
+                    f'Illegal format string {fmt!r}; two linestyle symbols')
             linestyle = c
             i += 1
         elif c in mlines.lineMarkers:
             if marker is not None:
                 raise ValueError(
-                    'Illegal format string "%s"; two marker symbols' % fmt)
+                    f'Illegal format string {fmt!r}; two marker symbols')
             marker = c
             i += 1
         elif c in mcolors.get_named_colors_mapping():
             if color is not None:
                 raise ValueError(
-                    'Illegal format string "%s"; two color symbols' % fmt)
+                    f'Illegal format string {fmt!r}; two color symbols')
             color = c
             i += 1
         elif c == 'C' and i < len(fmt) - 1:
@@ -2084,8 +2084,8 @@ def axis(self, *args, emit=True, **kwargs):
                     self.set_ylim([ylim[0], ylim[0] + edge_size],
                                   emit=emit, auto=False)
             else:
-                raise ValueError('Unrecognized string %s to axis; '
-                                 'try on or off' % s)
+                raise ValueError(f"Unrecognized string {s!r} to axis; "
+                                 "try 'on' or 'off'")
         else:
             if len(args) == 1:
                 limits = args[0]

diff --git a/lib/matplotlib/collections.py b/lib/matplotlib/collections.py
@@ -1764,7 +1764,7 @@ def _set_transforms(self):
         elif self._units == 'dots':
             sc = 1.0
         else:
-            raise ValueError('unrecognized units: %s' % self._units)
+            raise ValueError(f'Unrecognized units: {self._units!r}')
 
         self._transforms = np.zeros((len(self._widths), 3, 3))
         widths = self._widths * sc

diff --git a/lib/matplotlib/patches.py b/lib/matplotlib/patches.py
@@ -1469,7 +1469,7 @@ def _make_verts(self):
                     coords = np.concatenate([left_half_arrow[:-1],
                                              right_half_arrow[-2::-1]])
                 else:
-                    raise ValueError("Got unknown shape: %s" % self.shape)
+                    raise ValueError(f"Got unknown shape: {self._shape!r}")
             if distance != 0:
                 cx = self._dx / distance
                 sx = self._dy / distance
@@ -2191,12 +2191,13 @@ def __new__(cls, stylename, **kwargs):
         try:
             _cls = cls._style_list[_name]
         except KeyError as err:
-            raise ValueError(f"Unknown style: {stylename}") from err
+            raise ValueError(f"Unknown style: {stylename!r}") from err
         try:
             _args_pair = [cs.split("=") for cs in _list[1:]]
             _args = {k: float(v) for k, v in _args_pair}
         except ValueError as err:
-            raise ValueError(f"Incorrect style argument: {stylename}") from err
+            raise ValueError(
+                f"Incorrect style argument: {stylename!r}") from err
         return _cls(**{**_args, **kwargs})
 
     @classmethod

diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -146,7 +146,7 @@ def validate_bool(b):
     elif b in ('f', 'n', 'no', 'off', 'false', '0', 0, False):
         return False
     else:
-        raise ValueError('Could not convert "%s" to bool' % b)
+        raise ValueError(f'Cannot convert {b!r} to bool')
 
 
 def validate_axisbelow(s):
@@ -156,8 +156,8 @@ def validate_axisbelow(s):
         if isinstance(s, str):
             if s == 'line':
                 return 'line'
-    raise ValueError('%s cannot be interpreted as'
-                     ' True, False, or "line"' % s)
+    raise ValueError(f'{s!r} cannot be interpreted as'
+                     ' True, False, or "line"')
 
 
 def validate_dpi(s):
@@ -739,14 +739,14 @@ def validate_cycler(s):
             _DunderChecker().visit(ast.parse(s))
             s = eval(s, {'cycler': cycler, '__builtins__': {}})
         except BaseException as e:
-            raise ValueError("'%s' is not a valid cycler construction: %s" %
-                             (s, e)) from e
+            raise ValueError(f"{s!r} is not a valid cycler construction: {e}"
+                             ) from e
     # Should make sure what comes from the above eval()
     # is a Cycler object.
     if isinstance(s, Cycler):
         cycler_inst = s
     else:
-        raise ValueError("object was not a string or Cycler instance: %s" % s)
+        raise ValueError(f"Object is not a string or Cycler instance: {s!r}")
 
     unknowns = cycler_inst.keys - (set(_prop_validators) | set(_prop_aliases))
     if unknowns:

diff --git a/lib/matplotlib/sphinxext/plot_directive.py b/lib/matplotlib/sphinxext/plot_directive.py
@@ -183,7 +183,7 @@ def _option_boolean(arg):
     elif arg.strip().lower() in ('yes', '1', 'true'):
         return True
     else:
-        raise ValueError('"%s" unknown boolean' % arg)
+        raise ValueError(f'{arg!r} unknown boolean')
 
 
 def _option_context(arg):

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -5095,7 +5095,8 @@ def test_shared_aspect_error():
                            r"axis\(\) takes 0 or 1 positional arguments but 2"
                            " were given"),
                           (ValueError, ('foo', ), {},
-                           "Unrecognized string foo to axis; try on or off"),
+                           "Unrecognized string 'foo' to axis; try 'on' or "
+                           "'off'"),
                           (TypeError, ([1, 2], ), {},
                            "the first argument to axis*"),
                           (TypeError, tuple(), {'foo': None},
@@ -7574,6 +7575,19 @@ def test_empty_line_plots():
     assert len(line) == 1
 
 
+@pytest.mark.parametrize('fmt, match', (
+    ("foo", "Unrecognized character f in format string 'foo'"),
+    ("o+", "Illegal format string 'o\\+'; two marker symbols"),
+    (":-", "Illegal format string ':-'; two linestyle symbols"),
+    ("rk", "Illegal format string 'rk'; two color symbols"),
+    (":o-r", "Illegal format string ':o-r'; two linestyle symbols"),
+))
+def test_plot_format_errors(fmt, match):
+    fig, ax = plt.subplots()
+    with pytest.raises(ValueError, match=match):
+        ax.plot((0, 0), fmt)
+
+
 def test_clim():
     ax = plt.figure().add_subplot()
     for plot_method in [

diff --git a/lib/matplotlib/tests/test_patches.py b/lib/matplotlib/tests/test_patches.py
@@ -7,7 +7,7 @@
 
 import matplotlib as mpl
 from matplotlib.patches import (Annulus, Ellipse, Patch, Polygon, Rectangle,
-                                FancyArrowPatch)
+                                FancyArrowPatch, FancyArrow, BoxStyle)
 from matplotlib.testing.decorators import image_comparison, check_figures_equal
 from matplotlib.transforms import Bbox
 import matplotlib.pyplot as plt
@@ -692,6 +692,20 @@ def test_rotated_arcs():
         ax.set_aspect("equal")
 
 
+def test_fancyarrow_shape_error():
+    with pytest.raises(ValueError, match="Got unknown shape: 'foo'"):
+        FancyArrow(0, 0, 0.2, 0.2, shape='foo')
+
+
+@pytest.mark.parametrize('fmt, match', (
+    ("foo", "Unknown style: 'foo'"),
+    ("Round,foo", "Incorrect style argument: 'Round,foo'"),
+))
+def test_boxstyle_errors(fmt, match):
+    with pytest.raises(ValueError, match=match):
+        BoxStyle(fmt)
+
+
 @image_comparison(baseline_images=['annulus'], extensions=['png'])
 def test_annulus():
 

diff --git a/lib/matplotlib/tests/test_text.py b/lib/matplotlib/tests/test_text.py
@@ -251,6 +251,21 @@ def test_annotation_contains():
     assert ann.contains(event) == (False, {})
 
 
+@pytest.mark.parametrize('err, xycoords, match', (
+    (RuntimeError, print, "Unknown return type"),
+    (RuntimeError, [0, 0], r"Unknown coordinate type: \[0, 0\]"),
+    (ValueError, "foo", "'foo' is not a recognized coordinate"),
+    (ValueError, "foo bar", "'foo bar' is not a recognized coordinate"),
+    (ValueError, "offset foo", "xycoords cannot be an offset coordinate"),
+    (ValueError, "axes foo", "'foo' is not a recognized unit"),
+))
+def test_annotate_errors(err, xycoords, match):
+    fig, ax = plt.subplots()
+    with pytest.raises(err, match=match):
+        ax.annotate('xy', (0, 0), xytext=(0.5, 0.5), xycoords=xycoords)
+        fig.canvas.draw()
+
+
 @image_comparison(['titles'])
 def test_titles():
     # left and right side titles

diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
@@ -1466,7 +1466,7 @@ def _get_xy_transform(self, renderer, s):
 
         s_ = s.split()
         if len(s_) != 2:
-            raise ValueError("%s is not a recognized coordinate" % s)
+            raise ValueError(f"{s!r} is not a recognized coordinate")
 
         bbox0, xy0 = None, None
 
@@ -1506,12 +1506,12 @@ def _get_xy_transform(self, renderer, s):
                 w, h = bbox0.size
                 tr = Affine2D().scale(w, h)
             else:
-                raise ValueError("%s is not a recognized coordinate" % s)
+                raise ValueError(f"{unit!r} is not a recognized unit")
 
             return tr.translate(ref_x, ref_y)
 
         else:
-            raise ValueError("%s is not a recognized coordinate" % s)
+            raise ValueError(f"{s!r} is not a recognized coordinate")
 
     def _get_ref_xy(self, renderer):
         """