cli: consider "JJ:" lines as comments also when not followed by space

We currently ignore lines prefixed with "JJ: " (including the space)
in commit messages and in the list of sparse paths from `jj sparse
edit`. I think I included the trailing space in the prefix simply
because that's how we render comments line we insert before we ask the
user to edit the file. However, as #5004 says, Git doesn't require a
space after their "#" prefix. Neither does Mercurial after their "HG:"
prefix. So let's follow their lead and not require the trailing
space. Seems useful especially for people who have their editor
configured to strip trailing spaces.

CHANGELOG.md

@@ -20,6 +20,10 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 * `jj git push` no longer pushes new bookmarks by default. Use `--allow-new` to
   bypass this restriction.
 
+* Lines prefixed with "JJ:" in commit descriptions and in sparse patterns (from
+  `jj sparse edit`) are now stripped even if they are not immediately followed
+  by a space. [#5004](https://github.com/martinvonz/jj/issues/5004)
+
 ### Deprecations
 
 ### New features

cli/src/commands/sparse.rs

@@ -195,7 +195,7 @@ fn edit_sparse(
 
     content
         .lines()
-        .filter(|line| !line.starts_with("JJ: "))
+        .filter(|line| !line.starts_with("JJ:"))
         .map(|line| line.trim())
         .filter(|line| !line.is_empty())
         .map(|line| {

cli/src/config/templates.toml

@@ -30,7 +30,7 @@ if(overridden,
 '''
 
 # TODO: Provide hook point for diff customization (#1946)? We might want a
-# syntax to comment out full text diffs without using the "JJ: " prefix.
+# syntax to comment out full text diffs without using the "JJ:" prefix.
 draft_commit_description = '''
 concat(
   description,

cli/src/description_util.rs

@@ -28,7 +28,7 @@ where
 {
     let description = lines
         .into_iter()
-        .filter(|line| !line.as_ref().starts_with("JJ: "))
+        .filter(|line| !line.as_ref().starts_with("JJ:"))
         .fold(String::new(), |acc, line| acc + line.as_ref() + "\n");
     text_util::complete_newline(description.trim_matches('\n'))
 }
@@ -40,7 +40,7 @@ pub fn edit_description(
 ) -> Result<String, CommandError> {
     let description = format!(
         r#"{description}
-JJ: Lines starting with "JJ: " (like this one) will be removed.
+JJ: Lines starting with "JJ:" (like this one) will be removed.
 "#
     );
 
@@ -138,7 +138,7 @@ where
             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: ") {
+        else if !line.trim().is_empty() && !line.starts_with("JJ:") {
             return Err(ParseBulkEditMessageError::LineWithoutCommitHeader(
                 line.to_owned(),
             ));
@@ -237,7 +237,7 @@ pub fn description_template(
     // commit to be backed out, and the generated description could be set
     // without spawning editor.
 
-    // Named as "draft" because the output can contain "JJ: " comment lines.
+    // Named as "draft" because the output can contain "JJ:" comment lines.
     let template_key = "templates.draft_commit_description";
     let template_text = tx.settings().get_string(template_key)?;
     let template = tx.parse_commit_template(ui, &template_text)?;

cli/tests/test_commit_command.rs

@@ -53,7 +53,7 @@ fn test_commit_with_editor() {
         std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap(), @r###"
     initial
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 
     // Check that the editor content includes diff summary
@@ -70,7 +70,7 @@ fn test_commit_with_editor() {
     JJ:     A file1
     JJ:     A file2
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 }
 
@@ -127,7 +127,7 @@ fn test_commit_interactive() {
     JJ: This commit contains the following changes:
     JJ:     A file1
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 
     // Try again with --tool=<name>, which implies --interactive
@@ -148,7 +148,7 @@ fn test_commit_interactive() {
     JJ: This commit contains the following changes:
     JJ:     A file1
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 }
 
@@ -172,15 +172,13 @@ fn test_commit_with_default_description() {
     "###);
     insta::assert_snapshot!(
         std::fs::read_to_string(test_env.env_root().join("editor")).unwrap(), @r###"
-
-
     TESTED=TODO
 
     JJ: This commit contains the following changes:
     JJ:     A file1
     JJ:     A file2
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 }
 
@@ -221,14 +219,13 @@ fn test_commit_with_description_template() {
     test_env.jj_cmd_ok(&workspace_path, &["commit", "file1"]);
     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 08:05:08)
     JJ: Committer: Test User <[email protected]> (2001-02-03 08:05:08)
 
     JJ: file1 | 1 +
     JJ: 1 file changed, 1 insertion(+), 0 deletions(-)
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 
     // Only file2 with modified author should be included in the diff
@@ -242,30 +239,28 @@ fn test_commit_with_description_template() {
         ],
     );
     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: Another User <[email protected]> (2001-02-03 08:05:08)
     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.
-    "#);
+    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#"
-
+        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.
-    "#);
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
+    "###);
 }
 
 #[test]

cli/tests/test_describe_command.rs

@@ -57,7 +57,7 @@ fn test_describe() {
         std::fs::read_to_string(test_env.env_root().join("editor0")).unwrap(), @r###"
     description from CLI
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 
     // Set a description in editor
@@ -475,15 +475,13 @@ fn test_describe_default_description() {
     "###);
     insta::assert_snapshot!(
         std::fs::read_to_string(test_env.env_root().join("editor")).unwrap(), @r###"
-
-
     TESTED=TODO
 
     JJ: This commit contains the following changes:
     JJ:     A file1
     JJ:     A file2
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 }
 
@@ -566,15 +564,14 @@ fn test_describe_author() {
     ~
     "#);
     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: Super Seeder <[email protected]> (2001-02-03 08:05:12)
     JJ: Committer: Test User <[email protected]> (2001-02-03 08:05:12)
 
     JJ: 0 files changed, 0 insertions(+), 0 deletions(-)
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
-    "#);
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
+    "###);
 
     // Change the author for multiple commits (the committer is always reset)
     test_env.jj_cmd_ok(

cli/tests/test_split_command.rs

@@ -67,7 +67,7 @@ fn test_split_by_paths() {
     JJ: This commit contains the following changes:
     JJ:     A file2
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
     assert!(!test_env.env_root().join("editor1").exists());
 
@@ -192,7 +192,7 @@ fn test_split_with_non_empty_description() {
     JJ: This commit contains the following changes:
     JJ:     A file1
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
     insta::assert_snapshot!(
         std::fs::read_to_string(test_env.env_root().join("editor2")).unwrap(), @r###"
@@ -202,7 +202,7 @@ fn test_split_with_non_empty_description() {
     JJ: This commit contains the following changes:
     JJ:     A file2
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
     insta::assert_snapshot!(get_log_output(&test_env, &workspace_path), @r###"
     @  kkmpptxzrspx false part 2
@@ -254,7 +254,7 @@ fn test_split_with_default_description() {
     JJ: This commit contains the following changes:
     JJ:     A file1
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
     assert!(!test_env.env_root().join("editor2").exists());
     insta::assert_snapshot!(get_log_output(&test_env, &workspace_path), @r###"
@@ -373,7 +373,7 @@ fn test_split_siblings_no_descendants() {
     JJ: This commit contains the following changes:
     JJ:     A file1
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
     assert!(!test_env.env_root().join("editor2").exists());
 }
@@ -451,7 +451,7 @@ fn test_split_siblings_with_descendants() {
     JJ: This commit contains the following changes:
     JJ:     A file1
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
     insta::assert_snapshot!(
         std::fs::read_to_string(test_env.env_root().join("editor2")).unwrap(), @r###"
@@ -461,7 +461,7 @@ fn test_split_siblings_with_descendants() {
     JJ: This commit contains the following changes:
     JJ:     A file2
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 }
 
@@ -593,7 +593,7 @@ fn test_split_interactive() {
     JJ: This commit contains the following changes:
     JJ:     A file1
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 
     insta::assert_snapshot!(stdout, @"");

cli/tests/test_squash_command.rs

@@ -1074,7 +1074,7 @@ fn test_squash_description() {
     JJ: Description from source commit:
     source
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 
     // An explicit description on the command-line overrides prevents launching an

cli/tests/test_unsquash_command.rs

@@ -329,7 +329,7 @@ fn test_unsquash_description() {
     JJ: Description from source commit:
     source
 
-    JJ: Lines starting with "JJ: " (like this one) will be removed.
+    JJ: Lines starting with "JJ:" (like this one) will be removed.
     "###);
 
     // If the source's *content* doesn't become empty, then the source remains and