matplotlib
diff --git a/‎lib/matplotlib/axes/_axes.py
Lines changed: 7 additions & 8 deletions b/‎lib/matplotlib/axes/_axes.py
Lines changed: 7 additions & 8 deletions
diff --git a/‎lib/matplotlib/tests/test_axes.py
Lines changed: 25 additions & 0 deletions b/‎lib/matplotlib/tests/test_axes.py
Lines changed: 25 additions & 0 deletions
@@ -1313,9 +1313,6 @@ def eventplot(self, positions, orientation='horizontal', lineoffsets=1,
         else:
             positions = [np.asanyarray(positions)]
 
-        if len(positions) == 0:
-            return []
-
         poss = []
         for position in positions:
             poss += self._process_unit_info([("x", position)], kwargs)
@@ -1345,13 +1342,15 @@ def eventplot(self, positions, orientation='horizontal', lineoffsets=1,
         linewidths = np.asarray(linewidths)
 
         if len(lineoffsets) == 0:
-            lineoffsets = [None]
+            raise ValueError('lineoffsets cannot be empty')
         if len(linelengths) == 0:
-            linelengths = [None]
-        if len(linewidths) == 0:
-            lineoffsets = [None]
+            raise ValueError('linelengths cannot be empty')
+        if len(linestyles) == 0:
+            raise ValueError('linestyles cannot be empty')
         if len(linewidths) == 0:
-            lineoffsets = [None]
+            raise ValueError('linewidths cannot be empty')
+        if len(alpha) == 0:
+            raise ValueError('alpha cannot be empty')
         if len(colors) == 0:
             colors = [None]
         try:
 
@@ -6906,6 +6906,31 @@ def test_eventplot_legend():
     plt.legend()
 
 
+@pytest.mark.parametrize('err, args, kwargs, match', (
+        (ValueError, [[1]], {'lineoffsets': []}, 'lineoffsets cannot be empty'),
+        (ValueError, [[1]], {'linelengths': []}, 'linelengths cannot be empty'),
+        (ValueError, [[1]], {'linewidths': []}, 'linewidths cannot be empty'),
+        (ValueError, [[1]], {'linestyles': []}, 'linestyles cannot be empty'),
+        (ValueError, [[1]], {'alpha': []}, 'alpha cannot be empty'),
+        (ValueError, [1], {}, 'positions must be one-dimensional'),
+        (ValueError, [[1]], {'lineoffsets': [1, 2]},
+         'lineoffsets and positions are unequal sized sequences'),
+        (ValueError, [[1]], {'linelengths': [1, 2]},
+         'linelengths and positions are unequal sized sequences'),
+        (ValueError, [[1]], {'linewidths': [1, 2]},
+         'linewidths and positions are unequal sized sequences'),
+        (ValueError, [[1]], {'linestyles': [1, 2]},
+         'linestyles and positions are unequal sized sequences'),
+        (ValueError, [[1]], {'alpha': [1, 2]},
+         'alpha and positions are unequal sized sequences'),
+        (ValueError, [[1]], {'colors': [1, 2]},
+         'colors and positions are unequal sized sequences'),
+))
+def test_eventplot_errors(err, args, kwargs, match):
+    with pytest.raises(err, match=match):
+        plt.eventplot(*args, **kwargs)
+
+
 def test_bar_broadcast_args():
     fig, ax = plt.subplots()
     # Check that a bar chart with a single height for all bars works.