From 8c30fcef305dc59d817f10fe9c48227a7b329d90 Mon Sep 17 00:00:00 2001
From: Zsolt Dollenstein <zsol.zsol@gmail.com>
Date: Mon, 2 Dec 2024 10:00:59 +0000
Subject: [PATCH] rename: don't leave trailing commas (#1254)

When renaming the last element of a `from a import b,c` import, don't leave the trailing comma after `b`
---
 libcst/codemod/commands/rename.py            |  6 ++-
 libcst/codemod/commands/tests/test_rename.py | 45 ++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/libcst/codemod/commands/rename.py b/libcst/codemod/commands/rename.py
index 8b6302c9..9ad4334d 100644
--- a/libcst/codemod/commands/rename.py
+++ b/libcst/codemod/commands/rename.py
@@ -214,7 +214,7 @@ def leave_ImportFrom(
             return updated_node
 
         else:
-            new_names = []
+            new_names: list[cst.ImportAlias] = []
             for import_alias in names:
                 alias_name = get_full_name_for_node(import_alias.name)
                 if alias_name is not None:
@@ -252,6 +252,10 @@ def leave_ImportFrom(
                             # This import might be in use elsewhere in the code, so schedule a potential removal.
                             self.scheduled_removals.add(original_node)
                         new_names.append(import_alias)
+            if isinstance(new_names[-1].comma, cst.Comma):
+                new_names[-1] = new_names[-1].with_changes(
+                    comma=cst.MaybeSentinel.DEFAULT
+                )
 
             return updated_node.with_changes(names=new_names)
         return updated_node
diff --git a/libcst/codemod/commands/tests/test_rename.py b/libcst/codemod/commands/tests/test_rename.py
index 20e1c7d4..8245a34c 100644
--- a/libcst/codemod/commands/tests/test_rename.py
+++ b/libcst/codemod/commands/tests/test_rename.py
@@ -382,6 +382,28 @@ class Foo(d.z):
             new_name="d.z",
         )
 
+    def test_comma_import(self) -> None:
+        before = """
+            import a, b, c
+
+            class Foo(a.z):
+                bar: b.bar
+                baz: c.baz
+        """
+        after = """
+            import a, b, d
+
+            class Foo(a.z):
+                bar: b.bar
+                baz: d.baz
+        """
+        self.assertCodemod(
+            before,
+            after,
+            old_name="c.baz",
+            new_name="d.baz",
+        )
+
     def test_other_import_froms_untouched(self) -> None:
         before = """
             from a import b, c, d
@@ -405,6 +427,29 @@ class Foo(b):
             new_name="f.b",
         )
 
+    def test_comma_import_from(self) -> None:
+        before = """
+            from a import b, c, d
+
+            class Foo(b):
+                bar: c.bar
+                baz: d.baz
+        """
+        after = """
+            from a import b, c
+            from f import d
+
+            class Foo(b):
+                bar: c.bar
+                baz: d.baz
+        """
+        self.assertCodemod(
+            before,
+            after,
+            old_name="a.d",
+            new_name="f.d",
+        )
+
     def test_no_removal_of_import_in_use(self) -> None:
         before = """
             import a