FIX matplotlib#30007: Raise ValueError when all wedge sizes are zero in ax.pie (matplotlib#30019)

* Added a condition that throws a ValueError if all wedges are zero

* Removed "=" and added "==" for the condition statement

* Added a test case with all wedges as zero

* Fixed linting issue using pre-commit

* Adding more linting changes missed by pre-commit

* Running pre-commit hook again to remove the error

Author: albus-droid

lib/matplotlib/axes/_axes.py

@@ -3308,6 +3308,9 @@ def pie(self, x, explode=None, labels=None, colors=None,
 
         sx = x.sum()
 
+        if sx == 0:
+            raise ValueError('All wedge sizes are zero')
+
         if normalize:
             x = x / sx
         elif sx > 1:

lib/matplotlib/tests/test_axes.py

@@ -9747,3 +9747,9 @@ def test_pie_non_finite_values():
 
     with pytest.raises(ValueError, match='Wedge sizes must be finite numbers'):
         ax.pie(df, labels=['A', 'B', 'C'])
+
+
+def test_pie_all_zeros():
+    fig, ax = plt.subplots()
+    with pytest.raises(ValueError, match="All wedge sizes are zero"):
+        ax.pie([0, 0], labels=["A", "B"])