feat: complete JjLib describe implementation

src/jj/executor.rs

@@ -1,9 +1,9 @@
 use std::path::Path;
 
 use jj_lib::config::StackedConfig;
+use jj_lib::repo::{Repo, StoreFactories};
 use jj_lib::settings::UserSettings;
 use jj_lib::workspace::{Workspace, default_working_copy_factories};
-use jj_lib::repo::{Repo, StoreFactories};
 
 use crate::error::Error;
 use crate::jj::JjExecutor;
@@ -46,15 +46,82 @@ impl JjExecutor for JjLib {
         let settings = UserSettings::from_config(config)?;
         let store_factories = StoreFactories::default();
         let wc_factories = default_working_copy_factories();
-        match Workspace::load(&settings, &std::env::current_dir()?, &store_factories, &wc_factories) {
-            Ok(_) => Ok(true),
-            Err(_) => Ok(false)
+
+        // Check if the directory exists first
+        if !self.working_dir.exists() {
+            return Ok(false);
         }
+
+        // Try to load workspace from the working directory
+        // Walk up the directory tree until we find a repository or reach the root
+        let mut current_dir = self.working_dir.clone();
+        loop {
+            match Workspace::load(&settings, &current_dir, &store_factories, &wc_factories) {
+                Ok(_) => return Ok(true),
+                Err(_) => {
+                    // Move up to parent directory
+                    if !current_dir.pop() {
+                        // Reached root directory
+                        break;
+                    }
+                }
+            }
+        }
+
+        Ok(false)
     }
 
-    async fn describe(&self, _message: &str) -> Result<(), Error> {
-        // TODO: T018/T019 - Implement using jj-lib transactions
-        todo!("T018/T019: Implement describe() using jj-lib")
+    async fn describe(&self, message: &str) -> Result<(), Error> {
+        // Load the repository
+        let config = StackedConfig::with_defaults();
+        let settings = UserSettings::from_config(config)?;
+        let store_factories = StoreFactories::default();
+        let wc_factories = default_working_copy_factories();
+
+        let workspace = Workspace::load(
+            &settings,
+            &self.working_dir,
+            &store_factories,
+            &wc_factories,
+        )
+        .map_err(|_| Error::NotARepository)?;
+
+        let repo = workspace.repo_loader().load_at_head()?;
+
+        // Start a transaction
+        let mut tx = repo.start_transaction();
+        tx.set_tag("args".to_string(), "jj-cz describe".to_string());
+
+        // Get the current working copy commit (equivalent to @ revset)
+        let view = tx.repo().view();
+        let wc_commit_ids = view.wc_commit_ids();
+
+        if wc_commit_ids.is_empty() {
+            return Err(Error::JjOperation {
+                context: "No working copy commit found".to_string(),
+            });
+        }
+
+        // Get the first working copy commit (usually there's only one)
+        let wc_commit_id = wc_commit_ids.values().next().unwrap();
+        let wc_commit = tx.repo().store().get_commit(wc_commit_id)?;
+
+        // Rewrite the working copy commit with the new description
+        let commit_builder = tx
+            .repo_mut()
+            .rewrite_commit(&wc_commit)
+            .set_description(message);
+
+        // Write the modified commit
+        let _new_commit = commit_builder.write()?;
+
+        // Rebase descendants after the rewrite
+        tx.repo_mut().rebase_descendants()?;
+
+        // Finish the transaction
+        tx.commit("jj-cz: update commit description")?;
+
+        Ok(())
     }
 }
 
@@ -72,8 +139,7 @@ mod tests {
             .output()?;
 
         if !output.status.success() {
-            return Err(std::io::Error::new(
-                std::io::ErrorKind::Other,
+            return Err(std::io::Error::other(
                 format!(
                     "jj git init failed: {}",
                     String::from_utf8_lossy(&output.stderr)
@@ -91,12 +157,8 @@ mod tests {
             .output()?;
 
         if !output.status.success() {
-            return Err(std::io::Error::new(
-                std::io::ErrorKind::Other,
-                format!(
-                    "jj log failed: {}",
-                    String::from_utf8_lossy(&output.stderr)
-                ),
+            return Err(std::io::Error::other(
+                format!("jj log failed: {}", String::from_utf8_lossy(&output.stderr)),
             ));
         }
         Ok(String::from_utf8_lossy(&output.stdout).trim().to_string())
@@ -219,7 +281,11 @@ mod tests {
         let test_message = "feat(scope): add new feature";
         let result = jj_lib.describe(test_message).await;
 
-        assert!(result.is_ok(), "describe() should succeed, got {:?}", result);
+        assert!(
+            result.is_ok(),
+            "describe() should succeed, got {:?}",
+            result
+        );
 
         // Verify the commit description was updated
         let actual_description =
@@ -239,10 +305,14 @@ mod tests {
 
         let jj_lib = JjLib::with_working_dir(temp_dir.path());
 
-        let multiline_message = "feat: add feature\n\nThis is the body of the commit.\nIt spans multiple lines.";
+        let multiline_message =
+            "feat: add feature\n\nThis is the body of the commit.\nIt spans multiple lines.";
         let result = jj_lib.describe(multiline_message).await;
 
-        assert!(result.is_ok(), "describe() should succeed with multiline message");
+        assert!(
+            result.is_ok(),
+            "describe() should succeed with multiline message"
+        );
 
         let actual_description = get_commit_description(temp_dir.path()).unwrap();
         assert_eq!(actual_description, multiline_message);
@@ -264,7 +334,10 @@ mod tests {
 
         // Then clear it with empty message
         let result = jj_lib.describe("").await;
-        assert!(result.is_ok(), "describe() should succeed with empty message");
+        assert!(
+            result.is_ok(),
+            "describe() should succeed with empty message"
+        );
 
         let actual_description = get_commit_description(temp_dir.path()).unwrap();
         assert_eq!(actual_description, "", "Description should be cleared");
@@ -281,7 +354,10 @@ mod tests {
         let special_message = "fix: handle \"quotes\" and 'apostrophes' & <brackets>";
         let result = jj_lib.describe(special_message).await;
 
-        assert!(result.is_ok(), "describe() should handle special characters");
+        assert!(
+            result.is_ok(),
+            "describe() should handle special characters"
+        );
 
         let actual_description = get_commit_description(temp_dir.path()).unwrap();
         assert_eq!(actual_description, special_message);

src/jj/mod.rs

@@ -58,7 +58,8 @@ mod tests {
 
         /// Check if is_repository() was called
         fn was_is_repo_called(&self) -> bool {
-            self.is_repo_called.load(std::sync::atomic::Ordering::SeqCst)
+            self.is_repo_called
+                .load(std::sync::atomic::Ordering::SeqCst)
         }
 
         /// Get all messages passed to describe()