cli: push only branches pointing to @ by default

Since we now allow pushing open commits, we can implement support for
pushing the "current" branch by defining a "current" branch as any
branch pointing to `@`. That definition of a current/active seems to
have been the consensus in discussion #411.

Closes #246.

CHANGELOG.md

@@ -41,6 +41,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * `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).
 
+* `jj git push` now pushes only branches pointing to the `@` by default. Use
+  `--all` to push all branches.
+
 ### New features
 
 * `jj rebase` now accepts a `--branch/-b <revision>` argument, which can be used

docs/git-comparison.md

@@ -108,7 +108,7 @@ parent.
     </tr>
     <tr>
       <td>Update a remote repo with all branches from the local repo</td>
-      <td><code>jj git push [--remote &lt;remote&gt;]</code> (there is no
+      <td><code>jj git push --all [--remote &lt;remote&gt;]</code> (there is no
           support for pushing from non-Git repos yet)</td>
       <td><code>git push --all [&lt;remote&gt;]</code></td>
     </tr>

src/commands.rs

@@ -1858,9 +1858,11 @@ struct GitCloneArgs {
 
 /// Push to a Git remote
 ///
-/// By default, all branches are pushed. Use `--branch` if you want to push only
+/// By default, pushes any branches pointing to `@`. Use `--branch` to push a
-/// one branch.
+/// specific branch. Use `--all` to push all branches. Use `--change` to
+/// generate a branch name based on a specific commit's change ID.
 #[derive(clap::Args, Clone, Debug)]
+#[clap(group(ArgGroup::new("what").args(&["branch", "all", "change"])))]
 struct GitPushArgs {
     /// The remote to push to (only named remotes are supported)
     #[clap(long, default_value = "origin")]
@@ -1868,6 +1870,9 @@ struct GitPushArgs {
     /// Push only this branch
     #[clap(long)]
     branch: Option<String>,
+    /// Push all branches
+    #[clap(long)]
+    all: bool,
     /// Push this commit by creating a branch based on its change ID
     #[clap(long)]
     change: Option<String>,
@@ -5123,7 +5128,7 @@ fn cmd_git_push(
                 branch_name, &args.remote, branch_name
             )?;
         }
-    } else {
+    } else if args.all {
         // TODO: Is it useful to warn about conflicted branches?
         for (branch_name, branch_target) in workspace_command.repo().view().branches() {
             let push_action = classify_branch_push_action(branch_target, &args.remote);
@@ -5138,6 +5143,41 @@ fn cmd_git_push(
         }
         tx = workspace_command
             .start_transaction(&format!("push all branches to git remote {}", &args.remote));
+    } else {
+        match workspace_command
+            .repo()
+            .view()
+            .get_checkout(&workspace_command.workspace_id())
+        {
+            None => {
+                return Err(UserError(
+                    "Nothing checked out in this workspace".to_string(),
+                ));
+            }
+            Some(checkout) => {
+                let desired_target = Some(RefTarget::Normal(checkout.clone()));
+                for (branch_name, branch_target) in workspace_command.repo().view().branches() {
+                    if branch_target.local_target == desired_target {
+                        let push_action = classify_branch_push_action(branch_target, &args.remote);
+                        match push_action {
+                            BranchPushAction::AlreadyMatches => {}
+                            BranchPushAction::LocalConflicted => {}
+                            BranchPushAction::RemoteConflicted => {}
+                            BranchPushAction::Update(update) => {
+                                branch_updates.push((branch_name.clone(), update));
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        if branch_updates.is_empty() {
+            return Err(UserError("No current branch.".to_string()));
+        }
+        tx = workspace_command.start_transaction(&format!(
+            "push current branch(es) to git remote {}",
+            &args.remote
+        ));
     }
 
     if branch_updates.is_empty() {

tests/test_git_push.rs

@@ -64,14 +64,71 @@ fn set_up() -> (TestEnvironment, PathBuf) {
 fn test_git_push_nothing() {
     let (test_env, workspace_root) = set_up();
     // No branches to push yet
-    let stdout = test_env.jj_cmd_success(&workspace_root, &["git", "push"]);
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["git", "push", "--all"]);
     insta::assert_snapshot!(stdout, @r###"
     Nothing changed.
     "###);
 }
 
 #[test]
-fn test_git_push_success() {
+fn test_git_push_current_branch() {
+    let (test_env, workspace_root) = set_up();
+    // Update some branches. `branch1` is not a current branch, but `branch2` and
+    // `my-branch` are.
+    test_env.jj_cmd_success(
+        &workspace_root,
+        &["describe", "branch1", "-m", "modified branch1 commit"],
+    );
+    test_env.jj_cmd_success(
+        &workspace_root,
+        &["branch", "set", "--allow-backwards", "branch2"],
+    );
+    test_env.jj_cmd_success(&workspace_root, &["branch", "create", "my-branch"]);
+    test_env.jj_cmd_success(&workspace_root, &["describe", "-m", "foo"]);
+    // Check the setup
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["branch", "list"]);
+    insta::assert_snapshot!(stdout, @r###"
+    branch1: 5d0d85ed3da7 modified branch1 commit
+      @origin (ahead by 1 commits, behind by 1 commits): 545acdb23f70 description
+    branch2: 7840c9885676 foo
+      @origin (ahead by 1 commits, behind by 1 commits): 545acdb23f70 description
+    my-branch: 7840c9885676 foo
+    "###);
+    // First dry-run. `branch1` should not get pushed.
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["git", "push", "--dry-run"]);
+    insta::assert_snapshot!(stdout, @r###"
+    Branch changes to push to origin:
+      Move branch branch2 from 545acdb23f70 to 7840c9885676
+      Add branch my-branch to 7840c9885676
+    Dry-run requested, not pushing.
+    "###);
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["git", "push"]);
+    insta::assert_snapshot!(stdout, @r###"
+    Branch changes to push to origin:
+      Move branch branch2 from 545acdb23f70 to 7840c9885676
+      Add branch my-branch to 7840c9885676
+    "###);
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["branch", "list"]);
+    insta::assert_snapshot!(stdout, @r###"
+    branch1: 5d0d85ed3da7 modified branch1 commit
+      @origin (ahead by 1 commits, behind by 1 commits): 545acdb23f70 description
+    branch2: 7840c9885676 foo
+    my-branch: 7840c9885676 foo
+    "###);
+}
+
+#[test]
+fn test_git_push_no_current_branch() {
+    let (test_env, workspace_root) = set_up();
+    test_env.jj_cmd_success(&workspace_root, &["new"]);
+    let stderr = test_env.jj_cmd_failure(&workspace_root, &["git", "push"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: No current branch.
+    "###);
+}
+
+#[test]
+fn test_git_push_all() {
     let (test_env, workspace_root) = set_up();
     test_env.jj_cmd_success(&workspace_root, &["branch", "delete", "branch1"]);
     test_env.jj_cmd_success(
@@ -90,7 +147,7 @@ fn test_git_push_success() {
     my-branch: 7840c9885676 foo
     "###);
     // First dry-run
-    let stdout = test_env.jj_cmd_success(&workspace_root, &["git", "push", "--dry-run"]);
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["git", "push", "--all", "--dry-run"]);
     insta::assert_snapshot!(stdout, @r###"
     Branch changes to push to origin:
       Delete branch branch1 from 545acdb23f70
@@ -98,7 +155,7 @@ fn test_git_push_success() {
       Add branch my-branch to 7840c9885676
     Dry-run requested, not pushing.
     "###);
-    let stdout = test_env.jj_cmd_success(&workspace_root, &["git", "push"]);
+    let stdout = test_env.jj_cmd_success(&workspace_root, &["git", "push", "--all"]);
     insta::assert_snapshot!(stdout, @r###"
     Branch changes to push to origin:
       Delete branch branch1 from 545acdb23f70
@@ -133,7 +190,7 @@ fn test_git_push_conflict() {
     test_env.jj_cmd_success(&workspace_root, &["rebase", "-r", "@", "-d", "@--"]);
     test_env.jj_cmd_success(&workspace_root, &["branch", "set", "my-branch"]);
     test_env.jj_cmd_success(&workspace_root, &["close", "-m", "third"]);
-    let stderr = test_env.jj_cmd_failure(&workspace_root, &["git", "push"]);
+    let stderr = test_env.jj_cmd_failure(&workspace_root, &["git", "push", "--all"]);
     insta::assert_snapshot!(stderr, @r###"
     Error: Won't push commit 50ccff1aeab0 since it has conflicts
     "###);