From 9ee42ae53e264829daee318875f0b9a4bc22fe98 Mon Sep 17 00:00:00 2001
From: Charles Crete <charles@cretezy.com>
Date: Sun, 28 Apr 2024 12:18:52 -0400
Subject: [PATCH] cli: add `--create` to `branch set` to upsert branches

---
 CHANGELOG.md                     |  2 ++
 cli/src/commands/branch.rs       | 10 +++++++---
 cli/tests/cli-reference@.md.snap |  4 ++++
 cli/tests/test_branch_command.rs | 25 ++++++++++++++++++++++++-
 4 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f5e678c12e..a0d7ef5027 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -62,6 +62,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * `jj rebase` now accepts revsets resolving to multiple revisions with the
    `--revisions`/`-r` option.
 
+* `jj branch set` now accepts `-c`/`--create` option to create the branch if it does not exist.
+
 ### Fixed bugs
 
 * Revsets now support `\`-escapes in string literal.
diff --git a/cli/src/commands/branch.rs b/cli/src/commands/branch.rs
index 78f7fd2374..24a5d5d118 100644
--- a/cli/src/commands/branch.rs
+++ b/cli/src/commands/branch.rs
@@ -169,6 +169,10 @@ pub struct BranchSetArgs {
     #[arg(long, short = 'B')]
     pub allow_backwards: bool,
 
+    /// Allow creating the branch if it does not exist.
+    #[arg(long, short = 'c')]
+    pub create: bool,
+
     /// The branches to update.
     #[arg(required = true)]
     pub names: Vec<String>,
@@ -353,13 +357,13 @@ fn cmd_branch_set(
     let branch_names = &args.names;
     for name in branch_names {
         let old_target = repo.view().get_local_branch(name);
-        if old_target.is_absent() {
+        if !args.create && old_target.is_absent() {
             return Err(user_error_with_hint(
                 format!("No such branch: {name}"),
-                "Use `jj branch create` to create it.",
+                "Use `jj branch create` or `jj branch set --create` to create it.",
             ));
         }
-        if !args.allow_backwards && !is_fast_forward(old_target) {
+        if !args.allow_backwards && !old_target.is_absent() && !is_fast_forward(old_target) {
             return Err(user_error_with_hint(
                 format!("Refusing to move branch backwards or sideways: {name}"),
                 "Use --allow-backwards to allow it.",
diff --git a/cli/tests/cli-reference@.md.snap b/cli/tests/cli-reference@.md.snap
index 3574baf619..48e9ab9a70 100644
--- a/cli/tests/cli-reference@.md.snap
+++ b/cli/tests/cli-reference@.md.snap
@@ -355,6 +355,10 @@ Update an existing branch to point to a certain commit
 
   Possible values: `true`, `false`
 
+* `-c`, `--create` — Allow creating the branch if it does not exist
+
+  Possible values: `true`, `false`
+
 
 
 
diff --git a/cli/tests/test_branch_command.rs b/cli/tests/test_branch_command.rs
index eae3312b5d..0eada4c202 100644
--- a/cli/tests/test_branch_command.rs
+++ b/cli/tests/test_branch_command.rs
@@ -99,7 +99,7 @@ fn test_branch_move() {
     let stderr = test_env.jj_cmd_failure(&repo_path, &["branch", "set", "foo"]);
     insta::assert_snapshot!(stderr, @r###"
     Error: No such branch: foo
-    Hint: Use `jj branch create` to create it.
+    Hint: Use `jj branch create` or `jj branch set --create` to create it.
     "###);
 
     let (_stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["branch", "create", "foo"]);
@@ -128,6 +128,29 @@ fn test_branch_move() {
     insta::assert_snapshot!(stderr, @"");
 }
 
+#[test]
+fn test_branch_set_create() {
+    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");
+
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["branch", "set", "foo"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: No such branch: foo
+    Hint: Use `jj branch create` or `jj branch set --create` to create it.
+    "###);
+
+    let (_stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["branch", "set", "foo", "--create"]);
+    insta::assert_snapshot!(stderr, @"");
+
+    test_env.jj_cmd_ok(&repo_path, &["new"]);
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["branch", "create", "foo"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: Branch already exists: foo
+    Hint: Use `jj branch set` to update it.
+    "###);
+}
+
 #[test]
 fn test_branch_move_conflicting() {
     let test_env = TestEnvironment::default();