tests: assert result of TestEnvironment::jj_cmd_cli_error

In the test case `test_branch_mutually_exclusive_actions`, we weren't actually testing anything useful, because the interface has since changed to use subcommands instead of options. The test has been deleted in this commit, and `TestEnvironment::jj_cmd_cli_error` has been changed to return a `#[must_use]` `String` representing stderr. I also added `#[must_use]` to `TestEnvironment::jj_cmd_failure` while I was here.

tests/common/mod.rs

@@ -83,6 +83,7 @@ impl TestEnvironment {
 
     /// Run a `jj` command, check that it failed with code 1, and return its
     /// stderr
+    #[must_use]
     pub fn jj_cmd_failure(&self, current_dir: &Path, args: &[&str]) -> String {
         let assert = self.jj_cmd(current_dir, args).assert().code(1).stdout("");
         self.normalize_output(get_stderr_string(&assert))
@@ -90,8 +91,10 @@ impl TestEnvironment {
 
     /// Run a `jj` command and check that it failed with code 2 (for invalid
     /// usage)
-    pub fn jj_cmd_cli_error(&self, current_dir: &Path, args: &[&str]) {
-        self.jj_cmd(current_dir, args).assert().code(2).stdout("");
+    #[must_use]
+    pub fn jj_cmd_cli_error(&self, current_dir: &Path, args: &[&str]) -> String {
+        let assert = self.jj_cmd(current_dir, args).assert().code(2).stdout("");
+        self.normalize_output(get_stderr_string(&assert))
     }
 
     pub fn env_root(&self) -> &Path {
@@ -157,6 +160,7 @@ impl TestEnvironment {
     }
 
     pub fn normalize_output(&self, text: String) -> String {
+        let text = text.replace("jj.exe", "jj");
         let regex = Regex::new(&format!(
             r"{}(\S+)",
             regex::escape(&self.env_root.display().to_string())

tests/test_alias.rs

@@ -46,8 +46,14 @@ fn test_alias_calls_unknown_command() {
     foo = ["nonexistent"]
     "#,
     );
-    // Should get an error about the unknown command
-    test_env.jj_cmd_cli_error(&repo_path, &["foo"]);
+    let stderr = test_env.jj_cmd_cli_error(&repo_path, &["foo"]);
+    insta::assert_snapshot!(stderr, @r###"
+    error: The subcommand 'nonexistent' wasn't recognized
+
+    Usage: jj [OPTIONS] [COMMAND]
+
+    For more information try '--help'
+    "###);
 }
 
 #[test]

tests/test_branch_command.rs

@@ -18,16 +18,6 @@ use crate::common::{get_stderr_string, get_stdout_string, 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_cli_error(&repo_path, &["branch", "--forget", "--delete", "foo"]);
-    test_env.jj_cmd_cli_error(&repo_path, &["branch", "--allow-backwards", "foo"]);
-}
-
 #[test]
 fn test_branch_multiple_names() {
     let test_env = TestEnvironment::default();

tests/test_edit_command.rs

@@ -29,7 +29,15 @@ fn test_edit() {
     std::fs::write(repo_path.join("file1"), "1").unwrap();
 
     // Errors out without argument
-    test_env.jj_cmd_cli_error(&repo_path, &["edit"]);
+    let stderr = test_env.jj_cmd_cli_error(&repo_path, &["edit"]);
+    insta::assert_snapshot!(stderr, @r###"
+    error: The following required arguments were not provided:
+      <REVISION>
+
+    Usage: jj edit <REVISION>
+
+    For more information try '--help'
+    "###);
 
     // Makes the specified commit the working-copy commit
     let stdout = test_env.jj_cmd_success(&repo_path, &["edit", "@-"]);

tests/test_global_opts.rs

@@ -235,7 +235,7 @@ fn test_help() {
     let test_env = TestEnvironment::default();
 
     let stdout = test_env.jj_cmd_success(test_env.env_root(), &["touchup", "-h"]);
-    insta::assert_snapshot!(stdout.replace(".exe", ""), @r###"
+    insta::assert_snapshot!(stdout, @r###"
     Touch up the content changes in a revision
 
     Usage: jj touchup [OPTIONS]

tests/test_move_command.rs

@@ -68,7 +68,15 @@ fn test_move() {
     "###);
 
     // Errors out without arguments
-    test_env.jj_cmd_cli_error(&repo_path, &["move"]);
+    let stderr = test_env.jj_cmd_cli_error(&repo_path, &["move"]);
+    insta::assert_snapshot!(stderr, @r###"
+    error: The following required arguments were not provided:
+      <--from <FROM>|--to <TO>>
+
+    Usage: jj move <--from <FROM>|--to <TO>> [PATHS]...
+
+    For more information try '--help'
+    "###);
     // Errors out if source and destination are the same
     let stderr = test_env.jj_cmd_failure(&repo_path, &["move", "--to", "@"]);
     insta::assert_snapshot!(stderr, @r###"

tests/test_new_command.rs

@@ -84,8 +84,14 @@ fn test_new_merge() {
     "###);
 
     // `jj merge` with less than two arguments is an error
-    test_env.jj_cmd_cli_error(&repo_path, &["merge"]);
-    test_env.jj_cmd_cli_error(&repo_path, &["merge", "main"]);
+    let stderr = test_env.jj_cmd_cli_error(&repo_path, &["merge"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: Merge requires at least two revisions
+    "###);
+    let stderr = test_env.jj_cmd_cli_error(&repo_path, &["merge", "main"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: Merge requires at least two revisions
+    "###);
 
     // merge with non-unique revisions
     let stderr = test_env.jj_cmd_failure(&repo_path, &["new", "@", "c34d"]);
@@ -94,7 +100,10 @@ fn test_new_merge() {
     "###);
 
     // merge with root
-    test_env.jj_cmd_failure(&repo_path, &["new", "@", "root"]);
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["new", "@", "root"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: Cannot merge with root revision
+    "###);
 }
 
 fn get_log_output(test_env: &TestEnvironment, repo_path: &Path) -> String {

tests/test_rebase_command.rs

@@ -40,13 +40,37 @@ fn test_rebase_invalid() {
     create_commit(&test_env, &repo_path, "b", &["a"]);
 
     // Missing destination
-    test_env.jj_cmd_cli_error(&repo_path, &["rebase"]);
+    let stderr = test_env.jj_cmd_cli_error(&repo_path, &["rebase"]);
+    insta::assert_snapshot!(stderr, @r###"
+    error: The following required arguments were not provided:
+      --destination <DESTINATION>
+
+    Usage: jj rebase --destination <DESTINATION>
+
+    For more information try '--help'
+    "###);
 
     // Both -r and -s
+    let stderr =
         test_env.jj_cmd_cli_error(&repo_path, &["rebase", "-r", "a", "-s", "a", "-d", "b"]);
+    insta::assert_snapshot!(stderr, @r###"
+    error: The argument '--revision <REVISION>' cannot be used with '--source <SOURCE>'
+
+    Usage: jj rebase --destination <DESTINATION> --revision <REVISION>
+
+    For more information try '--help'
+    "###);
 
     // Both -b and -s
+    let stderr =
         test_env.jj_cmd_cli_error(&repo_path, &["rebase", "-b", "a", "-s", "a", "-d", "b"]);
+    insta::assert_snapshot!(stderr, @r###"
+    error: The argument '--branch <BRANCH>' cannot be used with '--source <SOURCE>'
+
+    Usage: jj rebase --destination <DESTINATION> --branch <BRANCH>
+
+    For more information try '--help'
+    "###);
 
     // Rebase onto descendant with -r
     let stderr = test_env.jj_cmd_failure(&repo_path, &["rebase", "-r", "a", "-d", "b"]);
@@ -290,7 +314,11 @@ fn test_rebase_multiple_destinations() {
     o 
     "###);
 
+    let stderr =
         test_env.jj_cmd_failure(&repo_path, &["rebase", "-r", "a", "-d", "b", "-d", "root"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: Cannot merge with root revision
+    "###);
 }
 
 #[test]

tests/test_restore_command.rs

@@ -191,5 +191,12 @@ fn test_restore_interactive() {
 
     // Combining paths with -i is not yet supported
     std::fs::write(&edit_script, "").unwrap();
-    test_env.jj_cmd_cli_error(&repo_path, &["restore", "-i", "file2"]);
+    let stderr = test_env.jj_cmd_cli_error(&repo_path, &["restore", "-i", "file2"]);
+    insta::assert_snapshot!(stderr, @r###"
+    error: The argument '--interactive' cannot be used with '[PATHS]...'
+
+    Usage: jj restore --interactive [PATHS]...
+
+    For more information try '--help'
+    "###);
 }

tests/test_untrack_command.rs

@@ -45,12 +45,20 @@ fn test_untrack() {
 
     // Errors out when not run at the head operation
     let stderr = test_env.jj_cmd_failure(&repo_path, &["untrack", "file1", "--at-op", "@-"]);
-    insta::assert_snapshot!(stderr.replace("jj.exe", "jj"), @r###"
+    insta::assert_snapshot!(stderr, @r###"
     Error: This command must be able to update the working copy.
     Hint: Don't use --at-op.
     "###);
     // Errors out when no path is specified
-    test_env.jj_cmd_cli_error(&repo_path, &["untrack"]);
+    let stderr = test_env.jj_cmd_cli_error(&repo_path, &["untrack"]);
+    insta::assert_snapshot!(stderr, @r###"
+    error: The following required arguments were not provided:
+      <PATHS>...
+
+    Usage: jj untrack <PATHS>...
+
+    For more information try '--help'
+    "###);
     // Errors out when a specified file is not ignored
     let stderr = test_env.jj_cmd_failure(&repo_path, &["untrack", "file1", "file1.bak"]);
     insta::assert_snapshot!(stderr, @r###"