Improve help text and error handling

shout-rs/.gitignore

@@ -0,0 +1 @@
+target/

shout-rs/src/main.rs

@@ -37,18 +37,55 @@ struct TestOpts {
     parallel: bool,
 }
 
+fn print_usage() {
+    eprintln!("Usage: shout [options] [command]");
+    eprintln!();
+    eprintln!("$ shell output tester");
+    eprintln!();
+    eprintln!("Options:");
+    eprintln!("  -V, --version              output the version number");
+    eprintln!("  -h, --help                 display help for command");
+    eprintln!();
+    eprintln!("Commands:");
+    eprintln!("  test [options] [files...]  Run .shout test files");
+    eprintln!("  version                    Print the version");
+    eprintln!("  example                    Print an example .shout file");
+    eprintln!("  help [command]             display help for command");
+}
+
+fn print_test_help() {
+    eprintln!("Usage: shout test [options] [files...]");
+    eprintln!();
+    eprintln!("Run .shout test files");
+    eprintln!();
+    eprintln!("Arguments:");
+    eprintln!("  files                      Files or directories to test");
+    eprintln!();
+    eprintln!("Options:");
+    eprintln!("  -u, --update               Rewrite expected output in-place with actual output");
+    eprintln!("  -k, --keep                 Keep temp directories after run");
+    eprintln!("  --clean-env                Start with empty environment");
+    eprintln!("  --path <path>              Prepend <path> to PATH (repeatable)");
+    eprintln!("  --timeout <dur>            Per-command timeout (default: 10s)");
+    eprintln!("  -v, --verbose              Print each command as it runs");
+    eprintln!("  --port-from <n>            Auto-assign $PORT starting from <n> (default: 5400)");
+    eprintln!("  -t, --filter <pattern>     Only run files matching <pattern> (substring match)");
+    eprintln!("  --parallel                 Run files in parallel");
+    eprintln!("  -h, --help                 display help for command");
+}
+
 fn parse_args() -> Option<(&'static str, TestOpts)> {
     let args: Vec<String> = std::env::args().skip(1).collect();
 
-    if args.is_empty() {
+    if args.is_empty() || args[0] == "-h" || args[0] == "--help" || args[0] == "help" {
-        eprintln!("Usage: shout <test|example|version> [options]");
+        print_usage();
-        process::exit(1);
+        process::exit(if args.is_empty() { 1 } else { 0 });
     }
 
     let subcommand = args[0].as_str();
 
     match subcommand {
-        "version" => {
+        "-V" | "--version" | "version" => {
             println!("{VERSION}");
             process::exit(0);
         }
@@ -59,6 +96,7 @@ fn parse_args() -> Option<(&'static str, TestOpts)> {
         "test" => {}
         other => {
             eprintln!("Unknown command: {other}");
+            eprintln!("Run 'shout --help' for usage");
             process::exit(1);
         }
     }
@@ -79,6 +117,10 @@ fn parse_args() -> Option<(&'static str, TestOpts)> {
     let mut i = 1;
     while i < args.len() {
         match args[i].as_str() {
+            "-h" | "--help" => {
+                print_test_help();
+                process::exit(0);
+            }
             "-u" | "--update" => opts.update = true,
             "-k" | "--keep" => opts.keep = true,
             "--clean-env" => opts.clean_env = true,