From e7077909c1ae24d8652afd360eabf6db5bc8a419 Mon Sep 17 00:00:00 2001
From: Aleksandr Mikhailov <AM5800@gmail.com>
Date: Tue, 24 Jan 2023 10:21:02 +0100
Subject: [PATCH] cli: fix jj squash on empty commit

Fixes #787
If `jj squash` is run on an empty commit, it fails with "Error: No changes selected"

With this change such squash command will behave like `jj abandon`.
---
 src/commands/mod.rs          |  2 +-
 tests/test_squash_command.rs | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/commands/mod.rs b/src/commands/mod.rs
index 7c63cfe50..1fe60dbe5 100644
--- a/src/commands/mod.rs
+++ b/src/commands/mod.rs
@@ -2136,7 +2136,7 @@ from the source will be moved into the parent.
         args.interactive,
         matcher.as_ref(),
     )?;
-    if &new_parent_tree_id == parent.tree_id() {
+    if args.interactive && &new_parent_tree_id == parent.tree_id() {
         return Err(user_error("No changes selected"));
     }
     // Abandon the child if the parent now has all the content from the child
diff --git a/tests/test_squash_command.rs b/tests/test_squash_command.rs
index a07e3914e..891f39dfe 100644
--- a/tests/test_squash_command.rs
+++ b/tests/test_squash_command.rs
@@ -311,6 +311,32 @@ fn test_squash_description() {
     "###);
 }
 
+#[test]
+fn test_squash_empty() {
+    let mut test_env = TestEnvironment::default();
+    test_env.jj_cmd_success(test_env.env_root(), &["init", "repo", "--git"]);
+    let repo_path = test_env.env_root().join("repo");
+
+    test_env.jj_cmd_success(&repo_path, &["commit", "-m", "parent"]);
+
+    let stdout = test_env.jj_cmd_success(&repo_path, &["squash"]);
+    insta::assert_snapshot!(stdout, @r###"
+    Working copy now at: e45abe2cd9a9 (no description set)
+    "###);
+    insta::assert_snapshot!(get_description(&test_env, &repo_path, "@-"), @r###"
+    parent
+    "###);
+
+    test_env.jj_cmd_success(&repo_path, &["describe", "-m", "child"]);
+    test_env.set_up_fake_editor();
+    test_env.jj_cmd_success(&repo_path, &["squash"]);
+    insta::assert_snapshot!(get_description(&test_env, &repo_path, "@-"), @r###"
+    parent
+
+    child
+    "###);
+}
+
 fn get_description(test_env: &TestEnvironment, repo_path: &Path, rev: &str) -> String {
     test_env.jj_cmd_success(
         repo_path,