feat(tsort): reject multiple input arguments with custom error

- Change FILE arg to accept zero or more inputs (appended), defaulting to "-" if none
- Add validation to error on more than one input with "extra operand" message
- Update test to expect new error format, matching GNU tsort behavior
- Unignore test_only_one_input_file after error message correction

Author: mattsu2020

src/uu/tsort/src/tsort.rs

@@ -10,7 +10,7 @@ use std::ffi::OsString;
 use std::path::Path;
 use thiserror::Error;
 use uucore::display::Quotable;
-use uucore::error::{UError, UResult};
+use uucore::error::{UError, UResult, USimpleError};
 use uucore::{format_usage, show};
 
 use uucore::translate;
@@ -49,15 +49,33 @@ impl UError for LoopNode<'_> {}
 pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     let matches = uucore::clap_localization::handle_clap_result(uu_app(), args)?;
 
-    let input = matches
-        .get_one::<OsString>(options::FILE)
-        .expect("Value is required by clap");
+    let mut inputs: Vec<OsString> = matches
+        .get_many::<OsString>(options::FILE)
+        .map(|vals| vals.cloned().collect())
+        .unwrap_or_default();
+
+    if inputs.is_empty() {
+        inputs.push(OsString::from("-"));
+    }
+
+    if inputs.len() > 1 {
+        return Err(USimpleError::new(
+            1,
+            format!(
+                "extra operand {}\nTry 'tsort --help' for more information.",
+                inputs[1].quote()
+            ),
+        )
+        .into());
+    }
+
+    let input = inputs.into_iter().next().expect("at least one input");
 
     let data = if input == "-" {
         let stdin = std::io::stdin();
         std::io::read_to_string(stdin)?
     } else {
-        let path = Path::new(input);
+        let path = Path::new(&input);
         if path.is_dir() {
             return Err(TsortError::IsDir(input.to_string_lossy().to_string()).into());
         }
@@ -104,10 +122,11 @@ pub fn uu_app() -> Command {
         )
         .arg(
             Arg::new(options::FILE)
-                .default_value("-")
                 .hide(true)
                 .value_parser(clap::value_parser!(OsString))
-                .value_hint(clap::ValueHint::FilePath),
+                .value_hint(clap::ValueHint::FilePath)
+                .num_args(0..)
+                .action(ArgAction::Append),
         )
 }
 

tests/by-util/test_tsort.rs

@@ -77,7 +77,7 @@ fn test_multiple_arguments() {
         .arg("call_graph.txt")
         .arg("invalid_file")
         .fails()
-        .stderr_contains("unexpected argument 'invalid_file' found");
+        .stderr_contains("extra operand 'invalid_file'");
 }
 
 #[test]
@@ -157,7 +157,7 @@ fn test_loop_for_iterative_dfs_correctness() {
 const TSORT_LOOP_STDERR: &str = "tsort: f: input contains a loop:\ntsort: s\ntsort: t\n";
 const TSORT_LOOP_STDERR_AC: &str = "tsort: f: input contains a loop:\ntsort: a\ntsort: b\ntsort: f: input contains a loop:\ntsort: a\ntsort: c\n";
 const TSORT_ODD_ERROR: &str = "tsort: -: input contains an odd number of tokens\n";
-const TSORT_UNEXPECTED_ARG_ERROR: &str = "tsort: error: unexpected argument 'g' found\n\nUsage: tsort [OPTIONS] FILE\n\nFor more information, try '--help'.\n";
+const TSORT_EXTRA_OPERAND_ERROR: &str = "tsort: extra operand 'g'\nTry 'tsort --help' for more information.\n";
 
 #[test]
 fn test_cycle_loop_from_file() {
@@ -233,7 +233,6 @@ fn test_odd_number_of_tokens() {
 }
 
 #[test]
-#[ignore = "After correcting the error message, execute."]
 fn test_only_one_input_file() {
     let (at, mut ucmd) = at_and_ucmd!();
     at.write("f", "");
@@ -243,5 +242,5 @@ fn test_only_one_input_file() {
         .arg("g")
         .fails_with_code(1)
         .stdout_is("")
-        .stderr_is(TSORT_UNEXPECTED_ARG_ERROR);
+        .stderr_is(TSORT_EXTRA_OPERAND_ERROR);
 }