cli: make jj branch --revision/--delete/--forget mutually-exclusive

src/commands.rs

@@ -1575,19 +1575,23 @@ struct BackoutArgs {
 #[derive(clap::Args, Clone, Debug)]
 struct BranchArgs {
     /// The branch's target revision
-    #[clap(long, short, default_value = "@")]
+    #[clap(long, short, default_value = "@", group = "action")]
     revision: String,
+
     /// Allow moving the branch backwards or sideways
-    #[clap(long)]
+    #[clap(long, requires = "revision")]
     allow_backwards: bool,
+
     /// Delete the branch locally
     ///
     /// The deletion will be propagated to remotes on push.
-    #[clap(long)]
+    #[clap(long, group = "action")]
     delete: bool,
+
     /// The name of the branch to move or delete
-    #[clap(long)]
+    #[clap(long, group = "action")]
     forget: bool,
+
     name: String,
 }
 

tests/test_branch_command.rs

@@ -0,0 +1,30 @@
+// 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 crate::common::TestEnvironment;
+
+pub mod common;
+
+#[test]
+fn test_branch_mutually_exclusive_actions() {
+    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");
+
+    test_env.jj_cmd_failure(&repo_path, &["branch", "--forget", "--delete", "foo"]);
+    test_env.jj_cmd_failure(
+        &repo_path,
+        &["branch", "--delete", "--allow-backwards", "foo"],
+    );
+}