cli: add a command for listing git remotes

Closes #243

src/commands.rs

@@ -1613,6 +1613,7 @@ struct GitRemoteArgs {
 enum GitRemoteCommands {
     Add(GitRemoteAddArgs),
     Remove(GitRemoteRemoveArgs),
+    List(GitRemoteListArgs),
 }
 
 /// Add a Git remote
@@ -1631,6 +1632,10 @@ struct GitRemoteRemoveArgs {
     remote: String,
 }
 
+/// List Git remotes
+#[derive(clap::Args, Clone, Debug)]
+struct GitRemoteListArgs {}
+
 /// Fetch from a Git remote
 #[derive(clap::Args, Clone, Debug)]
 struct GitFetchArgs {
@@ -4433,6 +4438,9 @@ fn cmd_git_remote(
         GitRemoteCommands::Remove(command_matches) => {
             cmd_git_remote_remove(ui, command, command_matches)
         }
+        GitRemoteCommands::List(command_matches) => {
+            cmd_git_remote_list(ui, command, command_matches)
+        }
     }
 }
 
@@ -4462,7 +4470,7 @@ fn cmd_git_remote_remove(
     let repo = workspace_command.repo();
     let git_repo = get_git_repo(repo.store())?;
     if git_repo.find_remote(&args.remote).is_err() {
-        return Err(CommandError::UserError("Remote doesn't exists".to_string()));
+        return Err(CommandError::UserError("Remote doesn't exist".to_string()));
     }
     git_repo
         .remote_delete(&args.remote)
@@ -4484,6 +4492,20 @@ fn cmd_git_remote_remove(
     Ok(())
 }
 
+fn cmd_git_remote_list(
+    ui: &mut Ui,
+    command: &CommandHelper,
+    _args: &GitRemoteListArgs,
+) -> Result<(), CommandError> {
+    let workspace_command = command.workspace_helper(ui)?;
+    let repo = workspace_command.repo();
+    let git_repo = get_git_repo(repo.store())?;
+    for remote in git_repo.remotes()?.iter().flatten() {
+        writeln!(ui, "{}", remote)?;
+    }
+    Ok(())
+}
+
 fn cmd_git_fetch(
     ui: &mut Ui,
     command: &CommandHelper,

tests/test_git_remotes.rs

@@ -0,0 +1,51 @@
+// 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_git_remotes() {
+    let test_env = TestEnvironment::default();
+
+    test_env.jj_cmd_success(test_env.env_root(), &["init", "--git", "repo"]);
+    let repo_path = test_env.env_root().join("repo");
+
+    let stdout = test_env.jj_cmd_success(&repo_path, &["git", "remote", "list"]);
+    insta::assert_snapshot!(stdout, @"");
+    let stdout = test_env.jj_cmd_success(
+        &repo_path,
+        &["git", "remote", "add", "foo", "http://example.com/repo/foo"],
+    );
+    insta::assert_snapshot!(stdout, @"");
+    let stdout = test_env.jj_cmd_success(
+        &repo_path,
+        &["git", "remote", "add", "bar", "http://example.com/repo/bar"],
+    );
+    insta::assert_snapshot!(stdout, @"");
+    let stdout = test_env.jj_cmd_success(&repo_path, &["git", "remote", "list"]);
+    insta::assert_snapshot!(stdout, @r###"
+    bar
+    foo
+    "###);
+    let stdout = test_env.jj_cmd_success(&repo_path, &["git", "remote", "remove", "foo"]);
+    insta::assert_snapshot!(stdout, @"");
+    let stdout = test_env.jj_cmd_success(&repo_path, &["git", "remote", "list"]);
+    insta::assert_snapshot!(stdout, @"bar
+");
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["git", "remote", "remove", "nonexistent"]);
+    insta::assert_snapshot!(stderr, @"Error: Remote doesn't exist
+");
+}