cli: add --author argument for commit and describe

CHANGELOG.md

@@ -56,6 +56,9 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   allows to set a name for the remote instead of using the default
   `origin`.
 
+* `jj commit` and `jj describe` now accept `--author` option allowing to quickly change
+  author of given commit.
+
 ### Fixed bugs
 
  * Fixed panic when parsing invalid conflict markers of a particular form.

cli/src/commands/commit.rs

@@ -22,6 +22,7 @@ use crate::command_error::CommandError;
 use crate::description_util::description_template;
 use crate::description_util::edit_description;
 use crate::description_util::join_message_paragraphs;
+use crate::description_util::parse_user_name_email;
 use crate::ui::Ui;
 
 /// Update the description and create a new change on top.
@@ -50,6 +51,11 @@ pub(crate) struct CommitArgs {
     /// $ JJ_USER='Foo Bar' [email protected] jj commit --reset-author
     #[arg(long)]
     reset_author: bool,
+    /// Set author to the provided string
+    ///
+    /// This changes author name and email.
+    #[arg(long, conflicts_with = "reset_author")]
+    author: Option<String>,
 }
 
 #[instrument(skip_all)]
@@ -106,6 +112,15 @@ new working-copy commit.
     if args.reset_author {
         commit_builder.set_author(commit_builder.committer().clone());
     }
+    if let Some(author) = &args.author {
+        let (name, email) = parse_user_name_email(author)?;
+        let new_author = jj_lib::backend::Signature {
+            name,
+            email,
+            timestamp: commit_builder.committer().timestamp.clone(),
+        };
+        commit_builder.set_author(new_author);
+    }
 
     let description = if !args.message_paragraphs.is_empty() {
         join_message_paragraphs(&args.message_paragraphs)

cli/src/commands/describe.rs

@@ -17,6 +17,7 @@ use std::io;
 use std::io::Read;
 
 use itertools::Itertools;
+use jj_lib::backend::Signature;
 use jj_lib::commit::CommitIteratorExt;
 use jj_lib::object_id::ObjectId;
 use tracing::instrument;
@@ -29,6 +30,7 @@ use crate::description_util::description_template;
 use crate::description_util::edit_description;
 use crate::description_util::edit_multiple_descriptions;
 use crate::description_util::join_message_paragraphs;
+use crate::description_util::parse_user_name_email;
 use crate::description_util::ParsedBulkEditMessage;
 use crate::ui::Ui;
 
@@ -72,6 +74,11 @@ pub(crate) struct DescribeArgs {
     /// $ JJ_USER='Foo Bar' [email protected] jj describe --reset-author
     #[arg(long)]
     reset_author: bool,
+    /// Set author to the provided string
+    ///
+    /// This changes author name and email while retaining timestamp.
+    #[arg(long, conflicts_with = "reset_author")]
+    author: Option<String>,
 }
 
 #[instrument(skip_all)]
@@ -112,6 +119,12 @@ pub(crate) fn cmd_describe(
         None
     };
 
+    let author_arg = args
+        .author
+        .as_deref()
+        .map(parse_user_name_email)
+        .transpose()?;
+
     let commit_descriptions: Vec<(_, _)> = if args.no_edit || shared_description.is_some() {
         commits
             .iter()
@@ -139,6 +152,14 @@ pub(crate) fn cmd_describe(
                     let new_author = commit_builder.committer().clone();
                     commit_builder.set_author(new_author);
                 }
+                if let Some((name, email)) = author_arg.clone() {
+                    let new_author = Signature {
+                        name,
+                        email,
+                        timestamp: commit.author().timestamp.clone(),
+                    };
+                    commit_builder.set_author(new_author);
+                }
                 let temp_commit = commit_builder.write_hidden()?;
                 Ok((commit.id(), temp_commit))
             })
@@ -195,7 +216,10 @@ pub(crate) fn cmd_describe(
     let commit_descriptions: HashMap<_, _> = commit_descriptions
         .into_iter()
         .filter_map(|(commit, new_description)| {
-            if *new_description == *commit.description() && !args.reset_author {
+            if *new_description == *commit.description()
+                && !args.reset_author
+                && author_arg.is_none()
+            {
                 None
             } else {
                 Some((commit.id(), new_description))
@@ -218,13 +242,21 @@ pub(crate) fn cmd_describe(
             .collect_vec(),
         |rewriter| {
             let old_commit_id = rewriter.old_commit().id().clone();
+            let new_author = author_arg.clone().map(|(name, email)| Signature {
+                name,
+                email,
+                timestamp: rewriter.old_commit().author().timestamp.clone(),
+            });
             let mut commit_builder = rewriter.rebase(command.settings())?;
             if let Some(description) = commit_descriptions.get(&old_commit_id) {
                 commit_builder = commit_builder.set_description(description);
                 if args.reset_author {
                     let new_author = commit_builder.committer().clone();
                     commit_builder = commit_builder.set_author(new_author);
                 }
+                if let Some(new_author) = new_author {
+                    commit_builder = commit_builder.set_author(new_author);
+                }
                 num_described += 1;
             } else {
                 num_rebased += 1;

cli/src/description_util.rs

@@ -14,6 +14,7 @@ use crate::cli_util::edit_temp_file;
 use crate::cli_util::short_commit_hash;
 use crate::cli_util::WorkspaceCommandHelper;
 use crate::cli_util::WorkspaceCommandTransaction;
+use crate::command_error::cli_error;
 use crate::command_error::CommandError;
 use crate::formatter::PlainTextFormatter;
 use crate::text_util;
@@ -251,13 +252,22 @@ pub fn description_template(
     Ok(output.into_string_lossy())
 }
 
+pub fn parse_user_name_email(author: &str) -> Result<(String, String), CommandError> {
+    let re = regex::Regex::new(r"(?<name>.*?)\s*<(?<email>.+)>").unwrap();
+    let captures = re
+        .captures(author)
+        .ok_or_else(|| cli_error("Invalid author string"))?;
+    Ok((captures["name"].to_string(), captures["email"].to_string()))
+}
+
 #[cfg(test)]
 mod tests {
     use indexmap::indexmap;
     use indoc::indoc;
     use maplit::hashmap;
 
     use super::parse_bulk_edit_message;
+    use super::parse_user_name_email;
     use crate::description_util::ParseBulkEditMessageError;
 
     #[test]
@@ -410,4 +420,33 @@ mod tests {
         assert!(result.duplicates.is_empty());
         assert!(result.unexpected.is_empty());
     }
+
+    #[test]
+    fn test_parse_author() {
+        let expected_name = "Example";
+        let expected_email = "[email protected]";
+        let parsed = parse_user_name_email(&format!("{expected_name} <{expected_email}>")).unwrap();
+        assert_eq!(
+            (expected_name.to_string(), expected_email.to_string()),
+            parsed
+        );
+    }
+
+    #[test]
+    fn test_parse_author_with_utf8() {
+        let expected_name = "Ąćęłńóśżź";
+        let expected_email = "[email protected]";
+        let parsed = parse_user_name_email(&format!("{expected_name} <{expected_email}>")).unwrap();
+        assert_eq!(
+            (expected_name.to_string(), expected_email.to_string()),
+            parsed
+        );
+    }
+
+    #[test]
+    fn test_parse_author_without_name() {
+        let expected_email = "[email protected]";
+        let parsed = parse_user_name_email(&format!("<{expected_email}>")).unwrap();
+        assert_eq!(("".to_string(), expected_email.to_string()), parsed);
+    }
 }

cli/tests/cli-reference@.md.snap

@@ -446,6 +446,9 @@ Update the description and create a new change on top
    You can use it in combination with the JJ_USER and JJ_EMAIL environment variables to set a different author:
 
    $ JJ_USER='Foo Bar' [email protected] jj commit --reset-author
+* `--author <AUTHOR>` — Set author to the provided string
+
+   This changes author name and email.
 
 
 
@@ -599,6 +602,9 @@ Starts an editor to let you edit the description of changes. The editor will be
    You can use it in combination with the JJ_USER and JJ_EMAIL environment variables to set a different author:
 
    $ JJ_USER='Foo Bar' [email protected] jj describe --reset-author
+* `--author <AUTHOR>` — Set author to the provided string
+
+   This changes author name and email while retaining timestamp.
 
 
 

cli/tests/test_commit_command.rs

@@ -215,6 +215,7 @@ fn test_commit_with_description_template() {
 
     std::fs::write(workspace_path.join("file1"), "foo\n").unwrap();
     std::fs::write(workspace_path.join("file2"), "bar\n").unwrap();
+    std::fs::write(workspace_path.join("file3"), "foobar\n").unwrap();
 
     // Only file1 should be included in the diff
     test_env.jj_cmd_ok(&workspace_path, &["commit", "file1"]);
@@ -230,19 +231,41 @@ fn test_commit_with_description_template() {
     JJ: Lines starting with "JJ: " (like this one) will be removed.
     "###);
 
-    // Timestamp after the reset should be available to the template
-    test_env.jj_cmd_ok(&workspace_path, &["commit", "--reset-author"]);
+    // Only file2 with modified author should be included in the diff
+    test_env.jj_cmd_ok(
+        &workspace_path,
+        &[
+            "commit",
+            "--author",
+            r#""Another User <[email protected]>""#,
+            "file2",
+        ],
+    );
     insta::assert_snapshot!(
-        std::fs::read_to_string(test_env.env_root().join("editor")).unwrap(), @r###"
+        std::fs::read_to_string(test_env.env_root().join("editor")).unwrap(), @r#"
 
-    JJ: Author: Test User <test[email protected]> (2001-02-03 08:05:09)
+    JJ: Author: "Another User <another[email protected]> (2001-02-03 08:05:09)
     JJ: Committer: Test User <[email protected]> (2001-02-03 08:05:09)
 
     JJ: file2 | 1 +
     JJ: 1 file changed, 1 insertion(+), 0 deletions(-)
 
     JJ: Lines starting with "JJ: " (like this one) will be removed.
-    "###);
+    "#);
+
+    // Timestamp after the reset should be available to the template
+    test_env.jj_cmd_ok(&workspace_path, &["commit", "--reset-author"]);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor")).unwrap(), @r#"
+
+    JJ: Author: Test User <[email protected]> (2001-02-03 08:05:10)
+    JJ: Committer: Test User <[email protected]> (2001-02-03 08:05:10)
+
+    JJ: file3 | 1 +
+    JJ: 1 file changed, 1 insertion(+), 0 deletions(-)
+
+    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    "#);
 }
 
 #[test]

cli/tests/test_describe_command.rs

@@ -525,29 +525,75 @@ fn test_describe_author() {
     ~
     "###);
 
-    // Reset the author for the latest commit (the committer is always reset)
+    // Change the author for the latest commit (the committer is always reset)
     test_env.jj_cmd_ok(
         &repo_path,
         &[
             "describe",
-            "--config-toml",
-            r#"user.name = "Ove Ridder"
-            user.email = "[email protected]""#,
             "--no-edit",
-            "--reset-author",
+            "--author",
+            r#""Super Seeder <[email protected]>""#,
         ],
     );
-    insta::assert_snapshot!(get_signatures(), @r###"
-    @  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:12.000 +07:00
-    │  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:12.000 +07:00
+    insta::assert_snapshot!(get_signatures(), @r#"
+    @  "Super Seeder super.seeder@example.com 2001-02-03 04:05:10.000 +07:00
+    │  Test User test.user@example.com 2001-02-03 04:05:12.000 +07:00
     ○  Test User [email protected] 2001-02-03 04:05:09.000 +07:00
     │  Test User [email protected] 2001-02-03 04:05:09.000 +07:00
     ○  Test User [email protected] 2001-02-03 04:05:08.000 +07:00
     │  Test User [email protected] 2001-02-03 04:05:08.000 +07:00
     ○  Test User [email protected] 2001-02-03 04:05:07.000 +07:00
     │  Test User [email protected] 2001-02-03 04:05:07.000 +07:00
     ~
-    "###);
+    "#);
+
+    // Change the author for multiple commits (the committer is always reset)
+    test_env.jj_cmd_ok(
+        &repo_path,
+        &[
+            "describe",
+            "@---",
+            "@-",
+            "--no-edit",
+            "--author",
+            r#""Super Seeder <[email protected]>""#,
+        ],
+    );
+    insta::assert_snapshot!(get_signatures(), @r#"
+    @  "Super Seeder [email protected] 2001-02-03 04:05:10.000 +07:00
+    │  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    ○  "Super Seeder [email protected] 2001-02-03 04:05:09.000 +07:00
+    │  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    ○  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    │  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    ○  "Super Seeder [email protected] 2001-02-03 04:05:07.000 +07:00
+    │  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    ~
+    "#);
+
+    // Reset the author for the latest commit (the committer is always reset)
+    test_env.jj_cmd_ok(
+        &repo_path,
+        &[
+            "describe",
+            "--config-toml",
+            r#"user.name = "Ove Ridder"
+            user.email = "[email protected]""#,
+            "--no-edit",
+            "--reset-author",
+        ],
+    );
+    insta::assert_snapshot!(get_signatures(), @r#"
+    @  Ove Ridder [email protected] 2001-02-03 04:05:16.000 +07:00
+    │  Ove Ridder [email protected] 2001-02-03 04:05:16.000 +07:00
+    ○  "Super Seeder [email protected] 2001-02-03 04:05:09.000 +07:00
+    │  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    ○  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    │  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    ○  "Super Seeder [email protected] 2001-02-03 04:05:07.000 +07:00
+    │  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    ~
+    "#);
 
     // Reset the author for multiple commits (the committer is always reset)
     test_env.jj_cmd_ok(
@@ -563,17 +609,17 @@ fn test_describe_author() {
             "--reset-author",
         ],
     );
-    insta::assert_snapshot!(get_signatures(), @r###"
-    @  Ove Ridder [email protected] 2001-02-03 04:05:14.000 +07:00
-    │  Ove Ridder [email protected] 2001-02-03 04:05:14.000 +07:00
-    ○  Ove Ridder [email protected] 2001-02-03 04:05:14.000 +07:00
-    │  Ove Ridder [email protected] 2001-02-03 04:05:14.000 +07:00
-    ○  Test User [email protected] 2001-02-03 04:05:08.000 +07:00
-    │  Ove Ridder [email protected] 2001-02-03 04:05:14.000 +07:00
-    ○  Ove Ridder [email protected] 2001-02-03 04:05:14.000 +07:00
-    │  Ove Ridder [email protected] 2001-02-03 04:05:14.000 +07:00
+    insta::assert_snapshot!(get_signatures(), @r#"
+    @  Ove Ridder [email protected] 2001-02-03 04:05:18.000 +07:00
+    │  Ove Ridder [email protected] 2001-02-03 04:05:18.000 +07:00
+    ○  Ove Ridder [email protected] 2001-02-03 04:05:18.000 +07:00
+    │  Ove Ridder [email protected] 2001-02-03 04:05:18.000 +07:00
+    ○  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    │  Ove Ridder [email protected] 2001-02-03 04:05:18.000 +07:00
+    ○  Ove Ridder [email protected] 2001-02-03 04:05:18.000 +07:00
+    │  Ove Ridder [email protected] 2001-02-03 04:05:18.000 +07:00
     ~
-    "###);
+    "#);
 }
 
 #[test]