tr: require second string argument when deleting and squeezing

src/uu/tr/src/tr.rs

@@ -64,6 +64,16 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
         ));
     }
 
+    if delete_flag & squeeze_flag && sets_len < 2 {
+        return Err(UUsageError::new(
+            1,
+            format!(
+                "missing operand after {}\nTwo strings must be given when deleting and squeezing.",
+                sets[0].quote()
+            ),
+        ));
+    }
+
     if sets_len > 1 {
         let start = "extra operand";
         if delete_flag && !squeeze_flag {

tests/by-util/test_tr.rs

@@ -163,6 +163,15 @@ fn test_translate_and_squeeze_multiple_lines() {
         .stdout_is("yaay\nyaay"); // spell-checker:disable-line
 }
 
+#[test]
+fn test_delete_and_squeeze_one_set() {
+    new_ucmd!()
+        .args(&["-ds", "a-z"])
+        .fails()
+        .stderr_contains("missing operand after 'a-z'")
+        .stderr_contains("Two strings must be given when deleting and squeezing.");
+}
+
 #[test]
 fn test_delete_and_squeeze() {
     new_ucmd!()