Fix formatting

Author: z3rone

pandas/core/reshape/merge.py

@@ -1624,7 +1624,7 @@ def _validate_left_right_on(self, left_on, right_on):
     @final
     def _validate_validate_kwd(self, validate: str) -> None:
         # Split validation string
-        validations = validate.split('+')
+        validations = validate.split("+")
 
         # Check uniqueness of each
         if self.left_index:
@@ -1654,17 +1654,20 @@ def _validate_validate_kwd(self, validate: str) -> None:
                     )
                 if not left_unique:
                     raise MergeError(
-                        "Merge keys are not unique in left dataset; not a one-to-one merge"
+                        "Merge keys are not unique in left dataset; "
+                        "not a one-to-one merge"
                     )
                 if not right_unique:
                     raise MergeError(
-                        "Merge keys are not unique in right dataset; not a one-to-one merge"
+                        "Merge keys are not unique in right dataset; "
+                        "not a one-to-one merge"
                     )
 
             elif validation in ["one_to_many", "1:m"]:
                 if not left_unique:
                     raise MergeError(
-                        "Merge keys are not unique in left dataset; not a one-to-many merge"
+                        "Merge keys are not unique in left dataset; "
+                        "not a one-to-many merge"
                     )
 
             elif validation in ["many_to_one", "m:1"]:
@@ -1680,33 +1683,33 @@ def _validate_validate_kwd(self, validate: str) -> None:
             elif validation in ["total"]:
                 if not left_total and not right_total:
                     raise MergeError(
-                        "Neither the merge keys in the left dataset are all present in "
-                        "the right dataset, nor the merge keys in the right dataset all "
-                        "present in the left dataset; not a total merge."
+                        "Neither the merge keys in the left dataset are all present "
+                        "in the right dataset, nor the merge keys in the right "
+                        "dataset all present in the left dataset; not a total merge."
                     )
                 if not left_total:
                     raise MergeError(
-                        "Merge keys in left dataset are not all present in the right dataset; "
-                        "not a total merge"
+                        "Merge keys in left dataset are not all present in the right "
+                        "dataset; not a total merge"
                     )
                 if not right_total:
                     raise MergeError(
-                        "Merge keys in right dataset are not all present in the left dataset; "
-                        "not a total merge"
+                        "Merge keys in right dataset are not all present "
+                        "in the left dataset; not a total merge"
                     )
 
             elif validation in ["left_total"]:
                 if not left_total:
                     raise MergeError(
-                        "Merge keys in left dataset are not all present in the right dataset; "
-                        "not a left total merge"
+                        "Merge keys in left dataset are not all present "
+                        "in the right dataset; not a left total merge"
                     )
 
             elif validation in ["right_total"]:
                 if not right_total:
                     raise MergeError(
-                        "Merge keys in right dataset are not all present in the left dataset; "
-                        "not a right total merge"
+                        "Merge keys in right dataset are not all present "
+                        "in the left dataset; not a right total merge"
                     )
 
             else:

pandas/tests/reshape/merge/test_merge.py

@@ -1205,12 +1205,19 @@ def test_validation(self):
 
         # Make sure left totality works
         result = merge(
-            left, right, left_index=True, right_index=True, validate="one_to_one+left_total"
+            left,
+            right,
+            left_index=True,
+            right_index=True,
+            validate="one_to_one+left_total",
         )
         tm.assert_frame_equal(result, expected)
 
         # Make sure right totality raises exception
-        msg = "Merge keys in right dataset are not all present in the left dataset; not a right total merge"
+        msg = (
+            "Merge keys in right dataset are not all present in the left dataset; "
+            "not a right total merge"
+        )
         with pytest.raises(MergeError, match=msg):
             merge(
                 left,
@@ -1221,7 +1228,10 @@ def test_validation(self):
             )
 
         # Make sure general totality raises exception
-        msg = "Merge keys in right dataset are not all present in the left dataset; not a total merge"
+        msg = (
+            "Merge keys in right dataset are not all present in the left dataset; "
+            "not a total merge"
+        )
         with pytest.raises(MergeError, match=msg):
             merge(
                 left,
@@ -1370,7 +1380,8 @@ def test_validation(self):
         tm.assert_frame_equal(result, expected_multi)
 
         right_total_ext = concat(
-            [right, DataFrame({"a": ["b"], "b": [1], "d": ["neigh"]}, index=[3])], sort=True
+            [right, DataFrame({"a": ["b"], "b": [1], "d": ["neigh"]}, index=[3])],
+            sort=True,
         )
         expected_total_ext = DataFrame(
             {
@@ -1385,9 +1396,12 @@ def test_validation(self):
         tm.assert_frame_equal(result, expected_total_ext)
 
         # Ensure not left total raises error
-        right_reduced = right.drop_duplicates(subset=['b'])
+        right_reduced = right.drop_duplicates(subset=["b"])
 
-        msg = "Merge keys in left dataset are not all present in the right dataset; not a left total merge"
+        msg = (
+            "Merge keys in left dataset are not all present in the right dataset; "
+            "not a left total merge"
+        )
         with pytest.raises(MergeError, match=msg):
             merge(
                 left,