cli: add jj edit for editing a commit in the wokring copy

CHANGELOG.md

@@ -34,7 +34,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * The [`$NO_COLOR` environment variable](https://no-color.org/) no longer
   overrides the `ui.color` configuration if explicitly set.
 
-* `jj edit` has been renamed to `jj touchup`.
+* `jj edit` has been renamed to `jj touchup`, and `jj edit` is now a new command
+  with different behavior. The new `jj edit` lets you edit a commit in the
+  working copy, even if the specified commit is closed.
 
 * `jj git push` no longer aborts if you attempt to push an open commit (but it
   now aborts if a commit does not have a description).

lib/src/repo.rs

@@ -597,7 +597,6 @@ impl MutableRepo {
     }
 
     pub fn edit(&mut self, workspace_id: WorkspaceId, commit: &Commit) {
-        assert!(commit.is_open(), "commit to edit is closed");
         self.leave_commit(&workspace_id);
         self.set_checkout(workspace_id, commit.id().clone());
     }
@@ -606,7 +605,6 @@ impl MutableRepo {
         let maybe_current_checkout_id = self.view.borrow().get_checkout(workspace_id).cloned();
         if let Some(current_checkout_id) = maybe_current_checkout_id {
             let current_checkout = self.store().get_commit(&current_checkout_id).unwrap();
-            assert!(current_checkout.is_open(), "current checkout is closed");
             if current_checkout.is_empty()
                 && current_checkout.description().is_empty()
                 && self.view().heads().contains(current_checkout.id())

src/commands.rs

@@ -1127,6 +1127,7 @@ enum Commands {
     Open(OpenArgs),
     Duplicate(DuplicateArgs),
     Abandon(AbandonArgs),
+    Edit(EditArgs),
     New(NewArgs),
     Move(MoveArgs),
     Squash(SquashArgs),
@@ -1401,6 +1402,16 @@ struct AbandonArgs {
     revisions: Vec<String>,
 }
 
+/// Edit a commit in the working copy
+///
+/// Puts the contents of a commit in the working copy for editing. Any changes
+/// you make in the working copy will update (amend) the commit.
+#[derive(clap::Args, Clone, Debug)]
+struct EditArgs {
+    /// The commit to edit
+    revision: String,
+}
+
 /// Create a new, empty change and check it out
 ///
 /// This may be useful if you want to make some changes you're unsure of on top
@@ -3439,6 +3450,22 @@ fn cmd_abandon(
     Ok(())
 }
 
+fn cmd_edit(ui: &mut Ui, command: &CommandHelper, args: &EditArgs) -> Result<(), CommandError> {
+    let mut workspace_command = command.workspace_helper(ui)?;
+    let new_commit = workspace_command.resolve_single_rev(ui, &args.revision)?;
+    let workspace_id = workspace_command.workspace_id();
+    if workspace_command.repo().view().get_checkout(&workspace_id) == Some(new_commit.id()) {
+        ui.write("Already editing that commit\n")?;
+    } else {
+        workspace_command.commit_working_copy(ui)?;
+        let mut tx =
+            workspace_command.start_transaction(&format!("edit commit {}", new_commit.id().hex()));
+        tx.mut_repo().edit(workspace_id, &new_commit);
+        workspace_command.finish_transaction(ui, tx)?;
+    }
+    Ok(())
+}
+
 fn cmd_new(ui: &mut Ui, command: &CommandHelper, args: &NewArgs) -> Result<(), CommandError> {
     let mut workspace_command = command.workspace_helper(ui)?;
     let parent = workspace_command.resolve_single_rev(ui, &args.revision)?;
@@ -5294,6 +5321,7 @@ where
         Commands::Open(sub_args) => cmd_open(ui, &command_helper, sub_args),
         Commands::Duplicate(sub_args) => cmd_duplicate(ui, &command_helper, sub_args),
         Commands::Abandon(sub_args) => cmd_abandon(ui, &command_helper, sub_args),
+        Commands::Edit(sub_args) => cmd_edit(ui, &command_helper, sub_args),
         Commands::New(sub_args) => cmd_new(ui, &command_helper, sub_args),
         Commands::Move(sub_args) => cmd_move(ui, &command_helper, sub_args),
         Commands::Squash(sub_args) => cmd_squash(ui, &command_helper, sub_args),

tests/test_edit_command.rs

@@ -0,0 +1,70 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::path::Path;
+
+use crate::common::TestEnvironment;
+
+pub mod common;
+
+#[test]
+fn test_edit() {
+    let test_env = TestEnvironment::default();
+    test_env.jj_cmd_success(test_env.env_root(), &["init", "repo", "--git"]);
+    let repo_path = test_env.env_root().join("repo");
+    std::fs::write(repo_path.join("file1"), "0").unwrap();
+    test_env.jj_cmd_success(&repo_path, &["close", "-m", "first"]);
+    test_env.jj_cmd_success(&repo_path, &["describe", "-m", "second"]);
+    std::fs::write(repo_path.join("file1"), "1").unwrap();
+
+    // Errors out without argument
+    test_env.jj_cmd_cli_error(&repo_path, &["edit"]);
+
+    // Can edit a closed commit
+    let stdout = test_env.jj_cmd_success(&repo_path, &["edit", "@-"]);
+    insta::assert_snapshot!(stdout, @r###"
+    Working copy now at: 5c9d6c787f29 first
+    Added 0 files, modified 1 files, removed 0 files
+    "###);
+    insta::assert_snapshot!(get_log_output(&test_env, &repo_path), @r###"
+    o 37ed5225d0fd open second
+    @ 5c9d6c787f29 closed first
+    o 000000000000 closed (no description set)
+    "###);
+    insta::assert_snapshot!(read_file(&repo_path.join("file1")), @"0");
+
+    // Changes in the working copy are amended into the commit
+    std::fs::write(repo_path.join("file2"), "0").unwrap();
+    insta::assert_snapshot!(get_log_output(&test_env, &repo_path), @r###"
+    Rebased 1 descendant commits onto updated working copy
+    o 57e61f6b2ce1 open second
+    @ f1b9706b17d0 closed first
+    o 000000000000 closed (no description set)
+    "###);
+}
+
+fn read_file(path: &Path) -> String {
+    String::from_utf8(std::fs::read(path).unwrap()).unwrap()
+}
+
+fn get_log_output(test_env: &TestEnvironment, cwd: &Path) -> String {
+    test_env.jj_cmd_success(
+        cwd,
+        &[
+            "log",
+            "-T",
+            r#"commit_id.short() " " if(open, "open", "closed")  " " description"#,
+        ],
+    )
+}