Validate set_tick_params(which=...)

Author: timhoffm

doc/api/next_api_changes/behaviour.rst

@@ -30,3 +30,9 @@ in that case.
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 `.axes.Axes.locator_params` used to accept any value for ``axis`` and silently
 did nothing, when passed an unsupported value. It now raises a ``ValueError``.
+
+``Axis.set_tick_params()`` validates ``which`` parameter
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+`.Axis.set_tick_params` (and the higher level `.axes.Axes.tick_params` and
+`.pyplot.tick_params`) used to accept any value for ``which`` and silently
+did nothing, when passed an unsupported value. It now raises a ``ValueError``.

lib/matplotlib/axis.py

@@ -889,9 +889,10 @@ def set_tick_params(self, which='major', reset=False, **kw):
         :meth:`matplotlib.axes.Axes.tick_params`.
         """
         dicts = []
-        if which == 'major' or which == 'both':
+        cbook._check_in_list(['major', 'minor', 'both'], which=which)
+        if which in ['major', 'both']:
             dicts.append(self._major_tick_kw)
-        if which == 'minor' or which == 'both':
+        if which in ['minor', 'both']:
             dicts.append(self._minor_tick_kw)
         kwtrans = self._translate_tick_kw(kw)
 
@@ -906,10 +907,10 @@ def set_tick_params(self, which='major', reset=False, **kw):
             self.reset_ticks()
         else:
             # apply the new kwargs to the existing ticks
-            if which == 'major' or which == 'both':
+            if which in ['major', 'both']:
                 for tick in self.majorTicks:
                     tick._apply_params(**kwtrans)
-            if which == 'minor' or which == 'both':
+            if which in ['minor', 'both']:
                 for tick in self.minorTicks:
                     tick._apply_params(**kwtrans)
             # special-case label color to also apply to the offset