tests/tty: fix test inputs

calling `pipe_in("</dev/null")` does not pipe in the `/dev/null` file,
but the raw string "</dev/null".

Closes https://github.com/uutils/coreutils/issues/2301

tests/by-util/test_tty.rs

@@ -1,11 +1,14 @@
+use std::fs::File;
+
 use crate::common::util::*;
 
 #[test]
 #[cfg(not(windows))]
 fn test_dev_null() {
     new_ucmd!()
-        .pipe_in("</dev/null")
+        .set_stdin(File::open("/dev/null").unwrap())
         .fails()
+        .code_is(1)
         .stdout_is("not a tty\n");
 }
 
@@ -14,44 +17,49 @@ fn test_dev_null() {
 fn test_dev_null_silent() {
     new_ucmd!()
         .args(&["-s"])
-        .pipe_in("</dev/null")
+        .set_stdin(File::open("/dev/null").unwrap())
         .fails()
+        .code_is(1)
         .stdout_is("");
 }
 
 #[test]
 fn test_close_stdin() {
-    new_ucmd!().pipe_in("<&-").fails().stdout_is("not a tty\n");
+    let mut child = new_ucmd!().run_no_wait();
+    drop(child.stdin.take());
+    let output = child.wait_with_output().unwrap();
+    assert_eq!(output.status.code(), Some(1));
+    assert_eq!(std::str::from_utf8(&output.stdout), Ok("not a tty\n"));
 }
 
 #[test]
 fn test_close_stdin_silent() {
-    new_ucmd!()
+    let mut child = new_ucmd!().arg("-s").run_no_wait();
-        .args(&["-s"])
+    drop(child.stdin.take());
-        .pipe_in("<&-")
+    let output = child.wait_with_output().unwrap();
-        .fails()
+    assert_eq!(output.status.code(), Some(1));
-        .stdout_is("");
+    assert!(output.stdout.is_empty());
 }
 
 #[test]
 fn test_close_stdin_silent_long() {
-    new_ucmd!()
+    let mut child = new_ucmd!().arg("--silent").run_no_wait();
-        .args(&["--silent"])
+    drop(child.stdin.take());
-        .pipe_in("<&-")
+    let output = child.wait_with_output().unwrap();
-        .fails()
+    assert_eq!(output.status.code(), Some(1));
-        .stdout_is("");
+    assert!(output.stdout.is_empty());
 }
 
 #[test]
 fn test_close_stdin_silent_alias() {
-    new_ucmd!()
+    let mut child = new_ucmd!().arg("--quiet").run_no_wait();
-        .args(&["--quiet"])
+    drop(child.stdin.take());
-        .pipe_in("<&-")
+    let output = child.wait_with_output().unwrap();
-        .fails()
+    assert_eq!(output.status.code(), Some(1));
-        .stdout_is("");
+    assert!(output.stdout.is_empty());
 }
 
 #[test]
 fn test_wrong_argument() {
-    new_ucmd!().args(&["a"]).fails();
+    new_ucmd!().args(&["a"]).fails().code_is(2);
 }