tsort: move from getopts to clap (#1867)

tests/by-util/test_tsort.rs

@@ -15,3 +15,36 @@ fn test_sort_self_loop() {
         .succeeds()
         .stdout_only("first\nsecond\n");
 }
+
+#[test]
+fn test_no_such_file() {
+    let result = new_ucmd!().arg("invalid_file_txt").run();
+
+    assert_eq!(true, result.stderr.contains("No such file or directory"));
+}
+
+#[test]
+fn test_version_flag() {
+    let version_short = new_ucmd!().arg("-V").run();
+    let version_long = new_ucmd!().arg("--version").run();
+
+    assert_eq!(version_short.stdout, version_long.stdout);
+}
+
+#[test]
+fn test_help_flag() {
+    let help_short = new_ucmd!().arg("-h").run();
+    let help_long = new_ucmd!().arg("--help").run();
+
+    assert_eq!(help_short.stdout, help_long.stdout);
+}
+
+#[test]
+fn test_multiple_arguments() {
+    let result = new_ucmd!()
+        .arg("call_graph.txt")
+        .arg("invalid_file.txt")
+        .run();
+
+    assert_eq!(true, result.stderr.contains("error: Found argument 'invalid_file.txt' which wasn't expected, or isn't valid in this context"))
+}