From 0dc39950f935e23069909d6f8e1e277ffe25e7b6 Mon Sep 17 00:00:00 2001
From: Jimmy Lai <yurinai@gmail.com>
Date: Wed, 25 Mar 2020 16:15:19 -0700
Subject: [PATCH] [AddImportsVisitor] generate deterministic add import output
 by sorting the sets.

---
 libcst/codemod/visitors/_add_imports.py        | 15 +++++++++------
 .../codemod/visitors/tests/test_add_imports.py | 18 ++++++++++++++++++
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/libcst/codemod/visitors/_add_imports.py b/libcst/codemod/visitors/_add_imports.py
index 1028e8d61..929cf8866 100644
--- a/libcst/codemod/visitors/_add_imports.py
+++ b/libcst/codemod/visitors/_add_imports.py
@@ -228,17 +228,20 @@ def leave_ImportFrom(
 
         # Now, do the actual update.
         return updated_node.with_changes(
-            names=(
-                *[libcst.ImportAlias(name=libcst.Name(imp)) for imp in imports_to_add],
-                *[
+            names=[
+                *(
+                    libcst.ImportAlias(name=libcst.Name(imp))
+                    for imp in sorted(imports_to_add)
+                ),
+                *(
                     libcst.ImportAlias(
                         name=libcst.Name(imp),
                         asname=libcst.AsName(name=libcst.Name(alias)),
                     )
-                    for (imp, alias) in aliases_to_add
-                ],
+                    for (imp, alias) in sorted(aliases_to_add)
+                ),
                 *updated_node.names,
-            )
+            ]
         )
 
     def _split_module(
diff --git a/libcst/codemod/visitors/tests/test_add_imports.py b/libcst/codemod/visitors/tests/test_add_imports.py
index 95b6d0aca..5ca4747df 100644
--- a/libcst/codemod/visitors/tests/test_add_imports.py
+++ b/libcst/codemod/visitors/tests/test_add_imports.py
@@ -620,3 +620,21 @@ def bar() -> int:
             [("a.b.c", "D", None)],
             context_override=CodemodContext(full_module_name="a.b.foobar"),
         )
+
+    def test_import_order(self) -> None:
+        """
+        The imports should be in alphabetic order of added imports, added import alias, original imports.
+        """
+        before = """
+            from a import b, e, h
+        """
+        after = """
+            from a import c, f, d as x, g as y, b, e, h
+        """
+
+        self.assertCodemod(
+            before,
+            after,
+            [("a", "f", None), ("a", "g", "y"), ("a", "c", None), ("a", "d", "x")],
+            context_override=CodemodContext(full_module_name="a.b.foobar"),
+        )