shuf: fix and test off-by-one errors around ranges

tests/by-util/test_shuf.rs

@@ -138,6 +138,99 @@ fn test_very_large_range_offset() {
     );
 }
 
+#[test]
+fn test_range_repeat_no_overflow_1_max() {
+    let upper_bound = std::usize::MAX;
+    let result = new_ucmd!()
+        .arg("-rn1")
+        .arg(&format!("-i1-{upper_bound}"))
+        .succeeds();
+    result.no_stderr();
+
+    let result_seq: Vec<usize> = result
+        .stdout_str()
+        .split('\n')
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    assert_eq!(result_seq.len(), 1, "Miscounted output length!");
+}
+
+#[test]
+fn test_range_repeat_no_overflow_0_max_minus_1() {
+    let upper_bound = std::usize::MAX - 1;
+    let result = new_ucmd!()
+        .arg("-rn1")
+        .arg(&format!("-i0-{upper_bound}"))
+        .succeeds();
+    result.no_stderr();
+
+    let result_seq: Vec<usize> = result
+        .stdout_str()
+        .split('\n')
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    assert_eq!(result_seq.len(), 1, "Miscounted output length!");
+}
+
+#[test]
+fn test_range_permute_no_overflow_1_max() {
+    let upper_bound = std::usize::MAX;
+    let result = new_ucmd!()
+        .arg("-n1")
+        .arg(&format!("-i1-{upper_bound}"))
+        .succeeds();
+    result.no_stderr();
+
+    let result_seq: Vec<usize> = result
+        .stdout_str()
+        .split('\n')
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    assert_eq!(result_seq.len(), 1, "Miscounted output length!");
+}
+
+#[test]
+fn test_range_permute_no_overflow_0_max_minus_1() {
+    let upper_bound = std::usize::MAX - 1;
+    let result = new_ucmd!()
+        .arg("-n1")
+        .arg(&format!("-i0-{upper_bound}"))
+        .succeeds();
+    result.no_stderr();
+
+    let result_seq: Vec<usize> = result
+        .stdout_str()
+        .split('\n')
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    assert_eq!(result_seq.len(), 1, "Miscounted output length!");
+}
+
+#[test]
+fn test_range_permute_no_overflow_0_max() {
+    // NOTE: This is different from GNU shuf!
+    // GNU shuf accepts -i0-MAX-1 and -i1-MAX, but not -i0-MAX.
+    // This feels like a bug in GNU shuf.
+    let upper_bound = std::usize::MAX;
+    let result = new_ucmd!()
+        .arg("-n1")
+        .arg(&format!("-i0-{upper_bound}"))
+        .succeeds();
+    result.no_stderr();
+
+    let result_seq: Vec<usize> = result
+        .stdout_str()
+        .split('\n')
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    assert_eq!(result_seq.len(), 1, "Miscounted output length!");
+}
+
 #[test]
 fn test_very_high_range_full() {
     let input_seq = vec![
@@ -626,7 +719,6 @@ fn test_shuf_multiple_input_line_count() {
 }
 
 #[test]
-#[ignore = "known issue"]
 fn test_shuf_repeat_empty_range() {
     new_ucmd!()
         .arg("-ri4-3")
@@ -653,3 +745,52 @@ fn test_shuf_repeat_empty_input() {
         .no_stdout()
         .stderr_only("shuf: no lines to repeat\n");
 }
+
+#[test]
+fn test_range_one_elem() {
+    new_ucmd!()
+        .arg("-i5-5")
+        .succeeds()
+        .no_stderr()
+        .stdout_only("5\n");
+}
+
+#[test]
+fn test_range_empty() {
+    new_ucmd!().arg("-i5-4").succeeds().no_output();
+}
+
+#[test]
+fn test_range_empty_minus_one() {
+    new_ucmd!().arg("-i5-3").succeeds().no_output();
+}
+
+#[test]
+fn test_range_repeat_one_elem() {
+    new_ucmd!()
+        .arg("-n1")
+        .arg("-ri5-5")
+        .succeeds()
+        .no_stderr()
+        .stdout_only("5\n");
+}
+
+#[test]
+fn test_range_repeat_empty() {
+    new_ucmd!()
+        .arg("-n1")
+        .arg("-ri5-4")
+        .fails()
+        .no_stdout()
+        .stderr_only("shuf: no lines to repeat\n");
+}
+
+#[test]
+fn test_range_repeat_empty_minus_one() {
+    new_ucmd!()
+        .arg("-n1")
+        .arg("-ri5-3")
+        .fails()
+        .no_stdout()
+        .stderr_only("shuf: no lines to repeat\n");
+}