cli: add --author argument for commit and describe

CHANGELOG.md

@@ -60,6 +60,9 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 * `jj squash`: the `-k` flag can be used as a shorthand for `--keep-emptied`.
 
+* `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

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use jj_lib::backend::Signature;
 use jj_lib::object_id::ObjectId;
 use jj_lib::repo::Repo;
 use tracing::instrument;
@@ -22,6 +23,7 @@ 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::text_util::parse_author_arg;
 use crate::ui::Ui;
 
 /// Update the description and create a new change on top.
@@ -50,6 +52,16 @@ 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 while retaining author
+    /// timestamp for non-discardable commits.
+    #[arg(
+        long,
+        conflicts_with = "reset_author",
+        value_parser = parse_author_arg
+    )]
+    author: Option<(String, String)>,
 }
 
 #[instrument(skip_all)]
@@ -106,6 +118,14 @@ new working-copy commit.
     if args.reset_author {
         commit_builder.set_author(commit_builder.committer().clone());
     }
+    if let Some((name, email)) = args.author.clone() {
+        let new_author = 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;
@@ -30,6 +31,7 @@ use crate::description_util::edit_description;
 use crate::description_util::edit_multiple_descriptions;
 use crate::description_util::join_message_paragraphs;
 use crate::description_util::ParsedBulkEditMessage;
+use crate::text_util::parse_author_arg;
 use crate::ui::Ui;
 
 /// Update the change description or other metadata
@@ -72,6 +74,16 @@ 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 author
+    /// timestamp for non-discardable commits.
+    #[arg(
+        long,
+        conflicts_with = "reset_author",
+        value_parser = parse_author_arg
+    )]
+    author: Option<(String, String)>,
 }
 
 #[instrument(skip_all)]
@@ -139,6 +151,14 @@ pub(crate) fn cmd_describe(
                     let new_author = commit_builder.committer().clone();
                     commit_builder.set_author(new_author);
                 }
+                if let Some((name, email)) = args.author.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 +215,12 @@ 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
+                && !args.author.as_ref().is_some_and(|(name, email)| {
+                    name != &commit.author().name || email != &commit.author().email
+                })
+            {
                 None
             } else {
                 Some((commit.id(), new_description))
@@ -225,6 +250,14 @@ pub(crate) fn cmd_describe(
                     let new_author = commit_builder.committer().clone();
                     commit_builder = commit_builder.set_author(new_author);
                 }
+                if let Some((name, email)) = args.author.clone() {
+                    let new_author = Signature {
+                        name,
+                        email,
+                        timestamp: commit_builder.author().timestamp.clone(),
+                    };
+                    commit_builder = commit_builder.set_author(new_author);
+                }
                 num_described += 1;
             } else {
                 num_rebased += 1;

cli/src/text_util.rs

@@ -261,6 +261,12 @@ pub fn write_wrapped(
     })
 }
 
+pub fn parse_author_arg(author: &str) -> Result<(String, String), &'static str> {
+    let re = regex::Regex::new(r"(?<name>.*?)\s*<(?<email>.+)>$").unwrap();
+    let captures = re.captures(author).ok_or("Invalid author string")?;
+    Ok((captures["name"].to_string(), captures["email"].to_string()))
+}
+
 #[cfg(test)]
 mod tests {
     use std::io::Write as _;
@@ -632,4 +638,33 @@ mod tests {
             "foo\n",
         );
     }
+
+    #[test]
+    fn test_parse_author() {
+        let expected_name = "Example";
+        let expected_email = "[email protected]";
+        let parsed = parse_author_arg(&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_author_arg(&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_author_arg(&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 while retaining author timestamp for non-discardable commits.
 
 
 
@@ -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 author timestamp for non-discardable commits.
 
 
 

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",
+            "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",
+            "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 04:05:12.000 +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",
+            "Super Seeder <[email protected]>",
+        ],
+    );
+    insta::assert_snapshot!(get_signatures(), @r#"
+    @  Super Seeder [email protected] 2001-02-03 04:05:12.000 +07:00
+    │  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    ○  Super Seeder [email protected] 2001-02-03 04:05:14.000 +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
+    │  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    ○  Super Seeder [email protected] 2001-02-03 04:05:14.000 +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 04:05:14.000 +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
+    │  Test User [email protected] 2001-02-03 04:05:14.000 +07:00
+    ○  Super Seeder [email protected] 2001-02-03 04:05:14.000 +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]