describe: allow updating the description of multiple commits

If multiple commits are provided, the description of each commit
will be combined into a single file for editing.

CHANGELOG.md

@@ -103,6 +103,8 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 * Added revset functions `author_date` and `committer_date`.
 
+* `jj describe` can now update the description of multiple commits.
+
 ### Fixed bugs
 
 * `jj status` will show different messages in a conflicted tree, depending

cli/src/command_error.rs

@@ -37,6 +37,7 @@ use jj_lib::workspace::WorkspaceInitError;
 use thiserror::Error;
 
 use crate::cli_util::short_operation_hash;
+use crate::description_util::ParseBulkEditMessageError;
 use crate::diff_util::DiffRenderError;
 use crate::formatter::{FormatRecorder, Formatter};
 use crate::merge_tools::{ConflictResolveError, DiffEditError, MergeToolConfigError};
@@ -541,6 +542,12 @@ impl From<GitIgnoreError> for CommandError {
     }
 }
 
+impl From<ParseBulkEditMessageError> for CommandError {
+    fn from(err: ParseBulkEditMessageError) -> Self {
+        user_error(err)
+    }
+}
+
 fn find_source_parse_error_hint(err: &dyn error::Error) -> Option<String> {
     let source = err.source()?;
     if let Some(source) = source.downcast_ref() {

cli/src/commands/describe.rs

@@ -12,33 +12,45 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use std::collections::HashMap;
 use std::io::{self, Read};
 
+use itertools::Itertools;
+use jj_lib::commit::CommitIteratorExt;
 use jj_lib::object_id::ObjectId;
 use tracing::instrument;
 
 use crate::cli_util::{CommandHelper, RevisionArg};
-use crate::command_error::CommandError;
+use crate::command_error::{user_error, CommandError};
-use crate::description_util::{description_template, edit_description, join_message_paragraphs};
+use crate::description_util::{
+    description_template, edit_description, edit_multiple_descriptions, join_message_paragraphs,
+    ParsedBulkEditMessage,
+};
 use crate::ui::Ui;
 
 /// Update the change description or other metadata
 ///
-/// Starts an editor to let you edit the description of a change. The editor
+/// Starts an editor to let you edit the description of changes. The editor
 /// will be $EDITOR, or `pico` if that's not defined (`Notepad` on Windows).
 #[derive(clap::Args, Clone, Debug)]
 #[command(visible_aliases = &["desc"])]
 pub(crate) struct DescribeArgs {
-    /// The revision whose description to edit
+    /// The revision(s) whose description to edit
     #[arg(default_value = "@")]
-    revision: RevisionArg,
+    revisions: Vec<RevisionArg>,
     /// Ignored (but lets you pass `-r` for consistency with other commands)
-    #[arg(short = 'r', hide = true)]
+    #[arg(short = 'r', hide = true, action = clap::ArgAction::Count)]
-    unused_revision: bool,
+    unused_revision: u8,
     /// The change description to use (don't open editor)
+    ///
+    /// If multiple revisions are specified, the same description will be used
+    /// for all of them.
     #[arg(long = "message", short, value_name = "MESSAGE")]
     message_paragraphs: Vec<String>,
     /// Read the change description from stdin
+    ///
+    /// If multiple revisions are specified, the same description will be used
+    /// for all of them.
     #[arg(long)]
     stdin: bool,
     /// Don't open an editor
@@ -65,39 +77,164 @@ pub(crate) fn cmd_describe(
     args: &DescribeArgs,
 ) -> Result<(), CommandError> {
     let mut workspace_command = command.workspace_helper(ui)?;
-    let commit = workspace_command.resolve_single_rev(&args.revision)?;
+    let commits: Vec<_> = workspace_command
-    workspace_command.check_rewritable([commit.id()])?;
+        .parse_union_revsets(&args.revisions)?
+        .evaluate_to_commits()?
+        .try_collect()?; // in reverse topological order
+    if commits.is_empty() {
+        writeln!(ui.status(), "No revisions to describe.")?;
+        return Ok(());
+    }
+    workspace_command.check_rewritable(commits.iter().ids())?;
 
     let mut tx = workspace_command.start_transaction();
-    let mut commit_builder = tx
+    let tx_description = if commits.len() == 1 {
-        .mut_repo()
+        format!("describe commit {}", commits[0].id().hex())
-        .rewrite_commit(command.settings(), &commit)
+    } else {
-        .detach();
+        format!(
-    if args.reset_author {
+            "describe commit {} and {} more",
-        commit_builder.set_author(commit_builder.committer().clone());
+            commits[0].id().hex(),
-    }
+            commits.len() - 1
+        )
+    };
 
-    let description = if args.stdin {
+    let shared_description = if args.stdin {
         let mut buffer = String::new();
         io::stdin().read_to_string(&mut buffer)?;
-        buffer
+        Some(buffer)
     } else if !args.message_paragraphs.is_empty() {
-        join_message_paragraphs(&args.message_paragraphs)
+        Some(join_message_paragraphs(&args.message_paragraphs))
-    } else if args.no_edit {
-        commit.description().to_owned()
     } else {
-        if commit_builder.description().is_empty() {
+        None
-            commit_builder.set_description(command.settings().default_description());
-        }
-        let temp_commit = commit_builder.write_hidden()?;
-        let template = description_template(&tx, "", &temp_commit)?;
-        edit_description(tx.base_repo(), &template, command.settings())?
     };
-    commit_builder.set_description(description);
 
-    if commit_builder.description() != commit.description() || args.reset_author {
+    let commit_descriptions: Vec<(_, _)> = if args.no_edit || shared_description.is_some() {
-        commit_builder.write(tx.mut_repo())?;
+        commits
+            .iter()
+            .map(|commit| {
+                let new_description = shared_description
+                    .as_deref()
+                    .unwrap_or_else(|| commit.description());
+                (commit, new_description.to_owned())
+            })
+            .collect()
+    } else {
+        let repo = tx.base_repo().clone();
+        let temp_commits: Vec<(_, _)> = commits
+            .iter()
+            // Edit descriptions in topological order
+            .rev()
+            .map(|commit| -> Result<_, CommandError> {
+                let mut commit_builder = tx
+                    .mut_repo()
+                    .rewrite_commit(command.settings(), commit)
+                    .detach();
+                if commit_builder.description().is_empty() {
+                    commit_builder.set_description(command.settings().default_description());
+                }
+                if args.reset_author {
+                    let new_author = commit_builder.committer().clone();
+                    commit_builder.set_author(new_author);
+                }
+                let temp_commit = commit_builder.write_hidden()?;
+                Ok((commit.id(), temp_commit))
+            })
+            .try_collect()?;
+
+        if let [(_, temp_commit)] = &*temp_commits {
+            let template = description_template(&tx, "", temp_commit)?;
+            let description = edit_description(&repo, &template, command.settings())?;
+
+            vec![(&commits[0], description)]
+        } else {
+            let ParsedBulkEditMessage {
+                descriptions,
+                missing,
+                duplicates,
+                unexpected,
+            } = edit_multiple_descriptions(&mut tx, &repo, &temp_commits, command.settings())?;
+            if !missing.is_empty() {
+                return Err(user_error(format!(
+                    "The description for the following commits were not found in the edited \
+                     message: {}",
+                    missing.join(", ")
+                )));
+            }
+            if !duplicates.is_empty() {
+                return Err(user_error(format!(
+                    "The following commits were found in the edited message multiple times: {}",
+                    duplicates.join(", ")
+                )));
+            }
+            if !unexpected.is_empty() {
+                return Err(user_error(format!(
+                    "The following commits were not being edited, but were found in the edited \
+                     message: {}",
+                    unexpected.join(", ")
+                )));
+            }
+
+            let commit_descriptions = commits
+                .iter()
+                .map(|commit| {
+                    let description = descriptions.get(commit.id()).unwrap().to_owned();
+                    (commit, description)
+                })
+                .collect();
+
+            commit_descriptions
+        }
+    };
+
+    // Filter out unchanged commits to avoid rebasing descendants in
+    // `transform_descendants` below unnecessarily.
+    let commit_descriptions: HashMap<_, _> = commit_descriptions
+        .into_iter()
+        .filter_map(|(commit, new_description)| {
+            if *new_description == *commit.description() && !args.reset_author {
+                None
+            } else {
+                Some((commit.id(), new_description))
+            }
+        })
+        .collect();
+
+    let mut num_described = 0;
+    let mut num_rebased = 0;
+    // Even though `MutRepo::rewrite_commit` and `MutRepo::rebase_descendants` can
+    // handle rewriting of a commit even if it is a descendant of another commit
+    // being rewritten, using `MutRepo::transform_descendants` prevents us from
+    // rewriting the same commit multiple times, and adding additional entries
+    // in the predecessor chain.
+    tx.mut_repo().transform_descendants(
+        command.settings(),
+        commit_descriptions
+            .keys()
+            .map(|&id| id.clone())
+            .collect_vec(),
+        |rewriter| {
+            let old_commit_id = rewriter.old_commit().id().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);
+                }
+                num_described += 1;
+            } else {
+                num_rebased += 1;
+            }
+            commit_builder.write()?;
+            Ok(())
+        },
+    )?;
+    if num_described > 1 {
+        writeln!(ui.status(), "Updated {} commits", num_described)?;
     }
-    tx.finish(ui, format!("describe commit {}", commit.id().hex()))?;
+    if num_rebased > 0 {
+        writeln!(ui.status(), "Rebased {} descendant commits", num_rebased)?;
+    }
+    tx.finish(ui, tx_description)?;
     Ok(())
 }

cli/src/description_util.rs

@@ -1,16 +1,30 @@
+use std::collections::HashMap;
 use std::io::Write as _;
 
 use bstr::ByteVec as _;
+use indexmap::IndexMap;
 use itertools::Itertools;
+use jj_lib::backend::CommitId;
 use jj_lib::commit::Commit;
 use jj_lib::repo::ReadonlyRepo;
 use jj_lib::settings::UserSettings;
+use thiserror::Error;
 
-use crate::cli_util::{edit_temp_file, WorkspaceCommandTransaction};
+use crate::cli_util::{edit_temp_file, short_commit_hash, WorkspaceCommandTransaction};
 use crate::command_error::CommandError;
 use crate::formatter::PlainTextFormatter;
 use crate::text_util;
 
+/// Cleanup a description by normalizing line endings, and removing leading and
+/// trailing blank lines.
+fn cleanup_description(description: &str) -> String {
+    let description = description
+        .lines()
+        .filter(|line| !line.starts_with("JJ: "))
+        .join("\n");
+    text_util::complete_newline(description.trim_matches('\n'))
+}
+
 pub fn edit_description(
     repo: &ReadonlyRepo,
     description: &str,
@@ -31,12 +45,126 @@ JJ: Lines starting with "JJ: " (like this one) will be removed.
         settings,
     )?;
 
-    // Normalize line ending, remove leading and trailing blank lines.
+    Ok(cleanup_description(&description))
-    let description = description
+}
-        .lines()
+
-        .filter(|line| !line.starts_with("JJ: "))
+/// Edits the descriptions of the given commits in a single editor session.
-        .join("\n");
+pub fn edit_multiple_descriptions(
-    Ok(text_util::complete_newline(description.trim_matches('\n')))
+    tx: &mut WorkspaceCommandTransaction,
+    repo: &ReadonlyRepo,
+    commits: &[(&CommitId, Commit)],
+    settings: &UserSettings,
+) -> Result<ParsedBulkEditMessage<CommitId>, CommandError> {
+    let mut commits_map = IndexMap::new();
+    let mut bulk_message = String::new();
+
+    for (commit_id, temp_commit) in commits.iter() {
+        let commit_hash = short_commit_hash(commit_id);
+        bulk_message.push_str("JJ: describe ");
+        bulk_message.push_str(&commit_hash);
+        bulk_message.push_str(" -------\n");
+        commits_map.insert(commit_hash, *commit_id);
+        let template = description_template(tx, "", temp_commit)?;
+        bulk_message.push_str(&template);
+        bulk_message.push('\n');
+    }
+    bulk_message.push_str("JJ: Lines starting with \"JJ: \" (like this one) will be removed.\n");
+
+    let bulk_message = edit_temp_file(
+        "description",
+        ".jjdescription",
+        repo.repo_path(),
+        &bulk_message,
+        settings,
+    )?;
+
+    Ok(parse_bulk_edit_message(&bulk_message, &commits_map)?)
+}
+
+#[derive(Debug)]
+pub struct ParsedBulkEditMessage<T> {
+    /// The parsed, formatted descriptions.
+    pub descriptions: HashMap<T, String>,
+    /// Commit IDs that were expected while parsing the edited messages, but
+    /// which were not found.
+    pub missing: Vec<String>,
+    /// Commit IDs that were found multiple times while parsing the edited
+    /// messages.
+    pub duplicates: Vec<String>,
+    /// Commit IDs that were found while parsing the edited messages, but which
+    /// were not originally being edited.
+    pub unexpected: Vec<String>,
+}
+
+#[derive(Debug, Error, PartialEq)]
+pub enum ParseBulkEditMessageError {
+    #[error(r#"Found the following line without a commit header: "{0}""#)]
+    LineWithoutCommitHeader(String),
+}
+
+/// Parse the bulk message of edited commit descriptions.
+fn parse_bulk_edit_message<T>(
+    message: &str,
+    commit_ids_map: &IndexMap<String, &T>,
+) -> Result<ParsedBulkEditMessage<T>, ParseBulkEditMessageError>
+where
+    T: Eq + std::hash::Hash + Clone,
+{
+    let mut descriptions = HashMap::new();
+    let mut duplicates = Vec::new();
+    let mut unexpected = Vec::new();
+
+    let mut messages: Vec<(&str, Vec<&str>)> = vec![];
+    for line in message.lines() {
+        if let Some(commit_id_prefix) = line.strip_prefix("JJ: describe ") {
+            let commit_id_prefix = commit_id_prefix.trim_end_matches(" -------");
+            messages.push((commit_id_prefix, vec![]));
+        } else if let Some((_, lines)) = messages.last_mut() {
+            lines.push(line);
+        }
+        // Do not allow lines without a commit header, except for empty lines or comments.
+        else if !line.trim().is_empty() && !line.starts_with("JJ: ") {
+            return Err(ParseBulkEditMessageError::LineWithoutCommitHeader(
+                line.to_owned(),
+            ));
+        };
+    }
+
+    for (commit_id_prefix, description_lines) in messages {
+        let commit_id = match commit_ids_map.get(commit_id_prefix) {
+            Some(&commit_id) => commit_id,
+            None => {
+                unexpected.push(commit_id_prefix.to_string());
+                continue;
+            }
+        };
+        if descriptions.contains_key(commit_id) {
+            duplicates.push(commit_id_prefix.to_string());
+            continue;
+        }
+        descriptions.insert(
+            commit_id.clone(),
+            cleanup_description(&description_lines.join("\n")),
+        );
+    }
+
+    let missing: Vec<_> = commit_ids_map
+        .iter()
+        .filter_map(|(commit_id_prefix, commit_id)| {
+            if !descriptions.contains_key(*commit_id) {
+                Some(commit_id_prefix.to_string())
+            } else {
+                None
+            }
+        })
+        .collect();
+
+    Ok(ParsedBulkEditMessage {
+        descriptions,
+        missing,
+        duplicates,
+        unexpected,
+    })
 }
 
 /// Combines the descriptions from the input commits. If only one is non-empty,
@@ -116,3 +244,159 @@ pub fn description_template(
     // Template output is usually UTF-8, but it can contain file content.
     Ok(output.into_string_lossy())
 }
+
+#[cfg(test)]
+mod tests {
+    use indexmap::indexmap;
+    use indoc::indoc;
+    use maplit::hashmap;
+
+    use super::parse_bulk_edit_message;
+    use crate::description_util::ParseBulkEditMessageError;
+
+    #[test]
+    fn test_parse_complete_bulk_edit_message() {
+        let result = parse_bulk_edit_message(
+            indoc! {"
+                JJ: describe 1 -------
+                Description 1
+
+                JJ: describe 2 -------
+                Description 2
+            "},
+            &indexmap! {
+                "1".to_string() => &1,
+                "2".to_string() => &2,
+            },
+        )
+        .unwrap();
+        assert_eq!(
+            result.descriptions,
+            hashmap! {
+                1 => "Description 1\n".to_string(),
+                2 => "Description 2\n".to_string(),
+            }
+        );
+        assert!(result.missing.is_empty());
+        assert!(result.duplicates.is_empty());
+        assert!(result.unexpected.is_empty());
+    }
+
+    #[test]
+    fn test_parse_bulk_edit_message_with_missing_descriptions() {
+        let result = parse_bulk_edit_message(
+            indoc! {"
+                JJ: describe 1 -------
+                Description 1
+            "},
+            &indexmap! {
+                "1".to_string() => &1,
+                "2".to_string() => &2,
+            },
+        )
+        .unwrap();
+        assert_eq!(
+            result.descriptions,
+            hashmap! {
+                1 => "Description 1\n".to_string(),
+            }
+        );
+        assert_eq!(result.missing, vec!["2".to_string()]);
+        assert!(result.duplicates.is_empty());
+        assert!(result.unexpected.is_empty());
+    }
+
+    #[test]
+    fn test_parse_bulk_edit_message_with_duplicate_descriptions() {
+        let result = parse_bulk_edit_message(
+            indoc! {"
+                JJ: describe 1 -------
+                Description 1
+
+                JJ: describe 1 -------
+                Description 1 (repeated)
+            "},
+            &indexmap! {
+                "1".to_string() => &1,
+            },
+        )
+        .unwrap();
+        assert_eq!(
+            result.descriptions,
+            hashmap! {
+                1 => "Description 1\n".to_string(),
+            }
+        );
+        assert!(result.missing.is_empty());
+        assert_eq!(result.duplicates, vec!["1".to_string()]);
+        assert!(result.unexpected.is_empty());
+    }
+
+    #[test]
+    fn test_parse_bulk_edit_message_with_unexpected_descriptions() {
+        let result = parse_bulk_edit_message(
+            indoc! {"
+                JJ: describe 1 -------
+                Description 1
+
+                JJ: describe 3 -------
+                Description 3 (unexpected)
+            "},
+            &indexmap! {
+                "1".to_string() => &1,
+            },
+        )
+        .unwrap();
+        assert_eq!(
+            result.descriptions,
+            hashmap! {
+                1 => "Description 1\n".to_string(),
+            }
+        );
+        assert!(result.missing.is_empty());
+        assert!(result.duplicates.is_empty());
+        assert_eq!(result.unexpected, vec!["3".to_string()]);
+    }
+
+    #[test]
+    fn test_parse_bulk_edit_message_with_no_header() {
+        let result = parse_bulk_edit_message(
+            indoc! {"
+                Description 1
+            "},
+            &indexmap! {
+                "1".to_string() => &1,
+            },
+        );
+        assert_eq!(
+            result.unwrap_err(),
+            ParseBulkEditMessageError::LineWithoutCommitHeader("Description 1".to_string())
+        );
+    }
+
+    #[test]
+    fn test_parse_bulk_edit_message_with_comment_before_header() {
+        let result = parse_bulk_edit_message(
+            indoc! {"
+                JJ: Custom comment and empty lines below should be accepted
+
+
+                JJ: describe 1 -------
+                Description 1
+            "},
+            &indexmap! {
+                "1".to_string() => &1,
+            },
+        )
+        .unwrap();
+        assert_eq!(
+            result.descriptions,
+            hashmap! {
+                1 => "Description 1\n".to_string(),
+            }
+        );
+        assert!(result.missing.is_empty());
+        assert!(result.duplicates.is_empty());
+        assert!(result.unexpected.is_empty());
+    }
+}

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

@@ -571,20 +571,24 @@ Update config file to set the given option to a given value
 
 Update the change description or other metadata
 
-Starts an editor to let you edit the description of a change. The editor will be $EDITOR, or `pico` if that's not defined (`Notepad` on Windows).
+Starts an editor to let you edit the description of changes. The editor will be $EDITOR, or `pico` if that's not defined (`Notepad` on Windows).
 
-**Usage:** `jj describe [OPTIONS] [REVISION]`
+**Usage:** `jj describe [OPTIONS] [REVISIONS]...`
 
 ###### **Arguments:**
 
-* `<REVISION>` — The revision whose description to edit
+* `<REVISIONS>` — The revision(s) whose description to edit
 
   Default value: `@`
 
 ###### **Options:**
 
 * `-m`, `--message <MESSAGE>` — The change description to use (don't open editor)
+
+   If multiple revisions are specified, the same description will be used for all of them.
 * `--stdin` — Read the change description from stdin
+
+   If multiple revisions are specified, the same description will be used for all of them.
 * `--no-edit` — Don't open an editor
 
    This is mainly useful in combination with e.g. `--reset-author`.

cli/tests/test_describe_command.rs

@@ -12,7 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
+
+use indoc::indoc;
 
 use crate::common::{get_stderr_string, TestEnvironment};
 
@@ -173,6 +175,200 @@ fn test_describe() {
     assert!(get_stderr_string(&assert).contains("bad-jj-editor-from-jj-editor-env"));
 }
 
+#[test]
+fn test_describe_multiple_commits() {
+    let mut test_env = TestEnvironment::default();
+    test_env.jj_cmd_ok(test_env.env_root(), &["git", "init", "repo"]);
+    let repo_path = test_env.env_root().join("repo");
+
+    let edit_script = test_env.set_up_fake_editor();
+
+    // Initial setup
+    test_env.jj_cmd_ok(&repo_path, &["new"]);
+    test_env.jj_cmd_ok(&repo_path, &["new"]);
+    insta::assert_snapshot!(get_log_output(&test_env, &repo_path), @r###"
+    @  c6349e79bbfd
+    ○  65b6b74e0897
+    ○  230dd059e1b0
+    ◆  000000000000
+    "###);
+
+    // Set the description of multiple commits using `-m` flag
+    let (stdout, stderr) = test_env.jj_cmd_ok(
+        &repo_path,
+        &["describe", "@", "@--", "-m", "description from CLI"],
+    );
+    insta::assert_snapshot!(stdout, @"");
+    insta::assert_snapshot!(stderr, @r###"
+    Updated 2 commits
+    Rebased 1 descendant commits
+    Working copy now at: kkmpptxz 41659b84 (empty) description from CLI
+    Parent commit      : rlvkpnrz 8d650510 (empty) (no description set)
+    "###);
+    insta::assert_snapshot!(get_log_output(&test_env, &repo_path), @r###"
+    @  41659b846096 description from CLI
+    ○  8d650510daad
+    ○  a42f5755e688 description from CLI
+    ◆  000000000000
+    "###);
+
+    // Check that the text file gets initialized with the current description of
+    // each commit and doesn't update commits if no changes are made.
+    // Commit descriptions are edited in topological order
+    std::fs::write(&edit_script, "dump editor0").unwrap();
+    let (stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["describe", "@", "@-"]);
+    insta::assert_snapshot!(stdout, @"");
+    insta::assert_snapshot!(stderr, @r###"
+    Nothing changed.
+    "###);
+    insta::assert_snapshot!(
+        std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap(), @r###"
+    JJ: describe 8d650510daad -------
+
+    JJ: describe 41659b846096 -------
+    description from CLI
+
+    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    "###);
+
+    // Set the description of multiple commits in the editor
+    std::fs::write(
+        &edit_script,
+        indoc! {"
+            write
+            JJ: describe 8d650510daad -------
+            description from editor of @-
+
+            further commit message of @-
+
+            JJ: describe 41659b846096 -------
+            description from editor of @
+
+            further commit message of @
+
+            JJ: Lines starting with \"JJ: \" (like this one) will be removed.
+        "},
+    )
+    .unwrap();
+    let (stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["describe", "@", "@-"]);
+    insta::assert_snapshot!(stdout, @"");
+    insta::assert_snapshot!(stderr, @r###"
+    Updated 2 commits
+    Working copy now at: kkmpptxz f203494a (empty) description from editor of @
+    Parent commit      : rlvkpnrz 0d76a92c (empty) description from editor of @-
+    "###);
+    insta::assert_snapshot!(get_log_output(&test_env, &repo_path), @r###"
+    @  f203494a4507 description from editor of @
+    │
+    │  further commit message of @
+    ○  0d76a92ca7cc description from editor of @-
+    │
+    │  further commit message of @-
+    ○  a42f5755e688 description from CLI
+    ◆  000000000000
+    "###);
+
+    // Fails if the edited message has a commit with multiple descriptions
+    std::fs::write(
+        &edit_script,
+        indoc! {"
+            write
+            JJ: describe 0d76a92ca7cc -------
+            first description from editor of @-
+
+            further commit message of @-
+
+            JJ: describe 0d76a92ca7cc -------
+            second description from editor of @-
+
+            further commit message of @-
+
+            JJ: describe f203494a4507 -------
+            updated description from editor of @
+
+            further commit message of @
+
+            JJ: Lines starting with \"JJ: \" (like this one) will be removed.
+        "},
+    )
+    .unwrap();
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["describe", "@", "@-"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: The following commits were found in the edited message multiple times: 0d76a92ca7cc
+    "###);
+
+    // Fails if the edited message has unexpected commit IDs
+    std::fs::write(
+        &edit_script,
+        indoc! {"
+            write
+            JJ: describe 000000000000 -------
+            unexpected commit ID
+
+            JJ: describe 0d76a92ca7cc -------
+            description from editor of @-
+
+            further commit message of @-
+
+            JJ: describe f203494a4507 -------
+            description from editor of @
+
+            further commit message of @
+
+            JJ: Lines starting with \"JJ: \" (like this one) will be removed.
+        "},
+    )
+    .unwrap();
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["describe", "@", "@-"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: The following commits were not being edited, but were found in the edited message: 000000000000
+    "###);
+
+    // Fails if the edited message has missing commit messages
+    std::fs::write(
+        &edit_script,
+        indoc! {"
+            write
+            JJ: describe f203494a4507 -------
+            description from editor of @
+
+            further commit message of @
+
+            JJ: Lines starting with \"JJ: \" (like this one) will be removed.
+        "},
+    )
+    .unwrap();
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["describe", "@", "@-"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: The description for the following commits were not found in the edited message: 0d76a92ca7cc
+    "###);
+
+    // Fails if the edited message has a line which does not have any preceding
+    // `JJ: describe` headers
+    std::fs::write(
+        &edit_script,
+        indoc! {"
+            write
+            description from editor of @-
+
+            JJ: describe f203494a4507 -------
+            description from editor of @
+
+            JJ: Lines starting with \"JJ: \" (like this one) will be removed.
+        "},
+    )
+    .unwrap();
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["describe", "@", "@-"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: Found the following line without a commit header: "description from editor of @-"
+    "###);
+
+    // Fails if the editor fails
+    std::fs::write(&edit_script, "fail").unwrap();
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["describe", "@", "@-"]);
+    assert!(stderr.contains("exited with an error"));
+}
+
 #[test]
 fn test_multiple_message_args() {
     let test_env = TestEnvironment::default();
@@ -295,19 +491,30 @@ fn test_describe_author() {
             &repo_path,
             &[
                 "log",
-                "-r@",
+                "-r..",
                 "-T",
                 r#"format_signature(author) ++ "\n" ++ format_signature(committer)"#,
             ],
         )
     };
+
+    // Initial setup
+    test_env.jj_cmd_ok(&repo_path, &["new"]);
+    test_env.jj_cmd_ok(&repo_path, &["new"]);
+    test_env.jj_cmd_ok(&repo_path, &["new"]);
     insta::assert_snapshot!(get_signatures(), @r###"
-    @  Test User test.user@example.com 2001-02-03 04:05:07.000 +07:00
+    @  Test User test.user@example.com 2001-02-03 04:05:10.000 +07:00
+    │  Test User test.user@example.com 2001-02-03 04:05:10.000 +07:00
+    ○  Test User test.user@example.com 2001-02-03 04:05:09.000 +07:00
+    │  Test User test.user@example.com 2001-02-03 04:05:09.000 +07:00
+    ○  Test User test.user@example.com 2001-02-03 04:05:08.000 +07:00
+    │  Test User test.user@example.com 2001-02-03 04:05:08.000 +07:00
+    ○  Test User test.user@example.com 2001-02-03 04:05:07.000 +07:00
     │  Test User test.user@example.com 2001-02-03 04:05:07.000 +07:00
     ~
     "###);
 
-    // Reset the author (the committer is always reset)
+    // Reset the author for the latest commit (the committer is always reset)
     test_env.jj_cmd_ok(
         &repo_path,
         &[
@@ -320,8 +527,40 @@ fn test_describe_author() {
         ],
     );
     insta::assert_snapshot!(get_signatures(), @r###"
-    @  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:09.000 +07:00
+    @  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:12.000 +07:00
-    │  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:09.000 +07:00
+    │  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:12.000 +07:00
+    ○  Test User test.user@example.com 2001-02-03 04:05:09.000 +07:00
+    │  Test User test.user@example.com 2001-02-03 04:05:09.000 +07:00
+    ○  Test User test.user@example.com 2001-02-03 04:05:08.000 +07:00
+    │  Test User test.user@example.com 2001-02-03 04:05:08.000 +07:00
+    ○  Test User test.user@example.com 2001-02-03 04:05:07.000 +07:00
+    │  Test User test.user@example.com 2001-02-03 04:05:07.000 +07:00
+    ~
+    "###);
+
+    // Reset the author for multiple commits (the committer is always reset)
+    test_env.jj_cmd_ok(
+        &repo_path,
+        &[
+            "describe",
+            "@---",
+            "@-",
+            "--config-toml",
+            r#"user.name = "Ove Ridder"
+            user.email = "ove.ridder@example.com""#,
+            "--no-edit",
+            "--reset-author",
+        ],
+    );
+    insta::assert_snapshot!(get_signatures(), @r###"
+    @  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:14.000 +07:00
+    │  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:14.000 +07:00
+    ○  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:14.000 +07:00
+    │  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:14.000 +07:00
+    ○  Test User test.user@example.com 2001-02-03 04:05:08.000 +07:00
+    │  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:14.000 +07:00
+    ○  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:14.000 +07:00
+    │  Ove Ridder ove.ridder@example.com 2001-02-03 04:05:14.000 +07:00
     ~
     "###);
 }
@@ -343,3 +582,8 @@ fn test_describe_avoids_unc() {
     // over 260 chars.
     assert_eq!(edited_path, dunce::simplified(&edited_path));
 }
+
+fn get_log_output(test_env: &TestEnvironment, repo_path: &Path) -> String {
+    let template = r#"commit_id.short() ++ " " ++ description"#;
+    test_env.jj_cmd_success(repo_path, &["log", "-T", template])
+}