From 331ebf4cef21e50b6df990a32ee77b53d36ebdf4 Mon Sep 17 00:00:00 2001
From: Martin von Zweigbergk <martinvonz@google.com>
Date: Sun, 12 Feb 2023 11:49:05 -0800
Subject: [PATCH] cli: use reverse-alphabet hex for branch name in `jj git push
 --change`

---
 CHANGELOG.md           | 11 +++++------
 src/cli_util.rs        |  5 ++++-
 tests/test_git_push.rs | 12 ++++++------
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5aec7aaa4..1b2be1ddd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -50,12 +50,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * The builtin `jj update` and `jj up` aliases for `jj checkout` have been
   deleted.
 
-* Change IDs are now in rendered using letters from the end of the alphabet
-  (backwards from 'z' through 'k') instead of the usual hex digits ('0' through
-  '9' and 'a' through 'f'). This is to clarify the distinction between change
-  IDs and commit IDs, and to allow more efficient lookup of unique prefixes.
-  This change doesn't affect the storage format; existing repositories will
-  remain usable.
+* Change IDs are now rendered using letters from the end of the alphabet (from
+  'z' through 'k') instead of the usual hex digits ('0' through '9' and 'a'
+  through 'f'). This is to clarify the distinction between change IDs and commit
+  IDs, and to allow more efficient lookup of unique prefixes. This change
+  doesn't affect the storage format; existing repositories will remain usable.
 
 ### New features
 
diff --git a/src/cli_util.rs b/src/cli_util.rs
index 5d427267f..56d7f8831 100644
--- a/src/cli_util.rs
+++ b/src/cli_util.rs
@@ -32,6 +32,7 @@ use jujutsu_lib::backend::{BackendError, ChangeId, CommitId, ObjectId, TreeId};
 use jujutsu_lib::commit::Commit;
 use jujutsu_lib::git::{GitExportError, GitImportError};
 use jujutsu_lib::gitignore::GitIgnoreFile;
+use jujutsu_lib::hex_util::to_reverse_hex;
 use jujutsu_lib::matchers::{EverythingMatcher, Matcher, PrefixMatcher, Visit};
 use jujutsu_lib::op_heads_store::{self, OpHeadResolutionError, OpHeadsStore};
 use jujutsu_lib::op_store::{OpStore, OpStoreError, OperationId, RefTarget, WorkspaceId};
@@ -1619,7 +1620,9 @@ pub fn short_commit_hash(commit_id: &CommitId) -> String {
 }
 
 pub fn short_change_hash(change_id: &ChangeId) -> String {
-    change_id.hex()[0..12].to_string()
+    // TODO: We could avoid the unwrap() and make this more efficient by converting
+    // straight from binary.
+    to_reverse_hex(&change_id.hex()[0..12]).unwrap()
 }
 
 pub fn short_operation_hash(operation_id: &OperationId) -> String {
diff --git a/tests/test_git_push.rs b/tests/test_git_push.rs
index 9b039d79f..944105499 100644
--- a/tests/test_git_push.rs
+++ b/tests/test_git_push.rs
@@ -221,9 +221,9 @@ fn test_git_push_changes() {
 
     let stdout = test_env.jj_cmd_success(&workspace_root, &["git", "push", "--change", "@"]);
     insta::assert_snapshot!(stdout, @r###"
-    Creating branch push-1b76972398e6 for revision @
+    Creating branch push-yostqsxwqrlt for revision @
     Branch changes to push to origin:
-      Add branch push-1b76972398e6 to 28d7620ea63a
+      Add branch push-yostqsxwqrlt to 28d7620ea63a
     "###);
     // test pushing two changes at once
     std::fs::write(workspace_root.join("file"), "modified2").unwrap();
@@ -232,10 +232,10 @@ fn test_git_push_changes() {
         &["git", "push", "--change", "@", "--change", "@-"],
     );
     insta::assert_snapshot!(stdout, @r###"
-    Creating branch push-19b790168e73 for revision @-
+    Creating branch push-yqosqzytrlsw for revision @-
     Branch changes to push to origin:
-      Force branch push-1b76972398e6 from 28d7620ea63a to 48d8c7948133
-      Add branch push-19b790168e73 to fa16a14170fb
+      Force branch push-yostqsxwqrlt from 28d7620ea63a to 48d8c7948133
+      Add branch push-yqosqzytrlsw to fa16a14170fb
     "###);
     // specifying the same change twice doesn't break things
     std::fs::write(workspace_root.join("file"), "modified3").unwrap();
@@ -245,7 +245,7 @@ fn test_git_push_changes() {
     );
     insta::assert_snapshot!(stdout, @r###"
     Branch changes to push to origin:
-      Force branch push-1b76972398e6 from 48d8c7948133 to b5f030322b1d
+      Force branch push-yostqsxwqrlt from 48d8c7948133 to b5f030322b1d
     "###);
 }