cli: add option to list only conflicted branches

As requested in #1471, I added a new flag for `jj branch list` to only show branches that are conflicted.

Adds a unit test to check for listing only conflicted branches and regenerates the cli output to incorporate the new flag.

Closes #1471

reformat

CHANGELOG.md

@@ -40,6 +40,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * `jj git push` now prints messages from the remote.
 
+* `jj branch list` now supports a `--conflicted/-c` option to show only conflicted branches.
+
 ### Fixed bugs
 
 ## [0.15.1] - 2024-03-06

cli/src/commands/branch.rs

@@ -109,6 +109,10 @@ pub struct BranchListArgs {
     #[arg(long, short, conflicts_with_all = ["all"])]
     tracked: bool,
 
+    /// Show conflicted branches only.
+    #[arg(long, short, conflicts_with_all = ["all"])]
+    conflicted: bool,
+
     /// Show branches whose local name matches
     ///
     /// By default, the specified name matches exactly. Use `glob:` prefix to
@@ -673,10 +677,11 @@ fn cmd_branch_list(
     let mut formatter = ui.stdout_formatter();
     let formatter = formatter.as_mut();
 
-    let branches_to_list = view.branches().filter(|&(name, _)| {
+    let branches_to_list = view.branches().filter(|(name, target)| {
         branch_names_to_list
             .as_ref()
             .map_or(true, |branch_names| branch_names.contains(name))
+            && (!args.conflicted || target.local_target.has_conflict())
     });
     for (name, branch_target) in branches_to_list {
         let (mut tracking_remote_refs, untracked_remote_refs) = branch_target

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

@@ -306,6 +306,10 @@ For information about branches, see https://github.com/martinvonz/jj/blob/main/d
 
   Possible values: `true`, `false`
 
+* `-c`, `--conflicted` — Show conflicted branches only
+
+  Possible values: `true`, `false`
+
 * `-r`, `--revisions <REVISIONS>` — Show branches whose local targets are in the given revisions
 
 

cli/tests/test_branch_command.rs

@@ -1348,6 +1348,45 @@ fn test_branch_list_tracked() {
     "###);
 }
 
+#[test]
+fn test_branch_list_conflicted() {
+    let test_env = TestEnvironment::default();
+    test_env.jj_cmd_ok(test_env.env_root(), &["init", "repo", "--git"]);
+    let repo_path = test_env.env_root().join("repo");
+
+    // Track existing branch. Local branch should result in conflict.
+    test_env.jj_cmd_ok(&repo_path, &["new", "root()", "-m", "a"]);
+    test_env.jj_cmd_ok(&repo_path, &["new", "root()", "-m", "b"]);
+    test_env.jj_cmd_ok(&repo_path, &["branch", "create", "bar"]);
+    test_env.jj_cmd_ok(
+        &repo_path,
+        &["branch", "create", "foo", "-r", "description(a)"],
+    );
+    test_env.jj_cmd_ok(
+        &repo_path,
+        &[
+            "branch",
+            "create",
+            "foo",
+            "-r",
+            "description(b)",
+            "--at-op=@-",
+        ],
+    );
+    test_env.jj_cmd_ok(&repo_path, &["status"]);
+    insta::assert_snapshot!(get_branch_output(&test_env, &repo_path), @r###"
+    bar: kkmpptxz 06a973bc (empty) b
+    foo (conflicted):
+      + rlvkpnrz d8d5f980 (empty) a
+      + kkmpptxz 06a973bc (empty) b
+    "###);
+    insta::assert_snapshot!(test_env.jj_cmd_success(&repo_path, &["branch", "list", "--conflicted"]), @r###"
+    foo (conflicted):
+      + rlvkpnrz d8d5f980 (empty) a
+      + kkmpptxz 06a973bc (empty) b
+    "###);
+}
+
 fn get_log_output(test_env: &TestEnvironment, cwd: &Path) -> String {
     let template = r#"branches ++ " " ++ commit_id.short()"#;
     test_env.jj_cmd_success(cwd, &["log", "-T", template])