temp(split): add --before flag to insert extracted changes before split commit

Author: claytonrcarter

git-branchless-opts/src/lib.rs

@@ -662,6 +662,10 @@ pub enum Command {
         #[clap(value_parser, required = true)]
         files: Vec<String>,
 
+        /// Insert the extracted commit before (as a parent of) the split commit.
+        #[clap(action, short = 'b', long)]
+        before: bool,
+
         /// Restack any descendents onto the split commit, not the extracted commit.
         #[clap(action, short = 'd', long)]
         detach: bool,

git-branchless/src/commands/mod.rs

@@ -181,6 +181,7 @@ fn command_main(ctx: CommandContext, opts: Opts) -> EyreExitOr<()> {
         },
 
         Command::Split {
+            before,
             detach,
             discard,
             files,
@@ -192,6 +193,7 @@ fn command_main(ctx: CommandContext, opts: Opts) -> EyreExitOr<()> {
             revset,
             &resolve_revset_options,
             files,
+            before,
             detach,
             discard,
             &move_options,

git-branchless/src/commands/split.rs

@@ -41,6 +41,7 @@ pub fn split(
     revset: Revset,
     resolve_revset_options: &ResolveRevsetOptions,
     files_to_extract: Vec<String>,
+    before: bool,
     detach: bool,
     discard: bool,
     move_options: &MoveOptions,
@@ -266,13 +267,18 @@ pub fn split(
                 reuse_parent_tree_if_possible: true,
             },
         )?;
+        let parents = if before {
+            split_commit.get_parents()
+        } else {
+            vec![split_commit]
+        };
         let extracted_commit_oid = repo.create_commit(
             None,
             &commit_to_split.get_author(),
             &commit_to_split.get_committer(),
             format!("temp(split): {message}").as_str(),
             &extracted_tree,
-            vec![&split_commit],
+            parents.iter().collect(),
         )?;
 
         // see git-branchless/src/commands/amend.rs:172

git-branchless/tests/test_split.rs

@@ -554,6 +554,66 @@ fn test_split_discard() -> eyre::Result<()> {
 
     Ok(())
 }
+#[test]
+fn test_split_insert_before() -> eyre::Result<()> {
+    let git = make_git()?;
+    git.init_repo()?;
+    git.detach_head()?;
+
+    git.write_file_txt("test1", "contents1")?;
+    git.write_file_txt("test2", "contents2")?;
+    git.write_file_txt("test3", "contents3")?;
+    git.run(&["add", "."])?;
+    git.run(&["commit", "-m", "first commit"])?;
+
+    git.commit_file("test3", 1)?;
+
+    {
+        let (stdout, _stderr) = git.branchless("smartlog", &[])?;
+        insta::assert_snapshot!(stdout, @r###"
+        O f777ecc (master) create initial.txt
+        |
+        o e48cdc5 first commit
+        |
+        @ 3d220e0 create test3.txt
+        "###);
+    }
+
+    {
+        let (stdout, _stderr) = git.branchless("split", &["HEAD~", "test2.txt", "--before"])?;
+        insta::assert_snapshot!(&stdout, @r###"
+            Attempting rebase in-memory...
+            [1/1] Committed as: f88fbe5 create test3.txt
+            branchless: processing 1 rewritten commit
+            branchless: running command: <git-executable> checkout f88fbe5901493ffe1c669cdb8aa5f056dc0bb605
+            In-memory rebase succeeded.
+            O f777ecc (master) create initial.txt
+            |
+            o 01523cc temp(split): test2.txt (+1)
+            |
+            o 2932db7 first commit
+            |
+            @ f88fbe5 create test3.txt
+        "###);
+    }
+
+    {
+        let (stdout, _stderr) = git.run(&["show", "--pretty=format:", "--stat", "HEAD~"])?;
+        insta::assert_snapshot!(&stdout, @"
+            test1.txt | 1 +
+            test3.txt | 1 +
+            2 files changed, 2 insertions(+)
+        ");
+
+        let (stdout, _stderr) = git.run(&["show", "--pretty=format:", "--stat", "HEAD~2"])?;
+        insta::assert_snapshot!(&stdout, @"
+            test2.txt | 1 +
+            1 file changed, 1 insertion(+)
+        ");
+    }
+
+    Ok(())
+}
 
 #[test]
 fn test_split_undo_works() -> eyre::Result<()> {