Add shuf tests (#1958)

* Add tests for shuf

* Fixup GNU tests for shuf

tests/by-util/test_shuf.rs

@@ -1,7 +1,168 @@
-// ToDO: add more tests
-
 use crate::common::util::*;
 
+#[test]
+fn test_output_is_random_permutation() {
+    let input_seq = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    let input = input_seq
+        .iter()
+        .map(|x| x.to_string())
+        .collect::<Vec<String>>()
+        .join("\n");
+
+    let result = new_ucmd!()
+        .pipe_in(input.as_bytes())
+        .succeeds()
+        .no_stderr()
+        .stdout
+        .clone();
+
+    let mut result_seq: Vec<i32> = result
+        .split("\n")
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    result_seq.sort();
+    assert_ne!(result, input, "Output is not randomised");
+    assert_eq!(result_seq, input_seq, "Output is not a permutation");
+}
+
+#[test]
+fn test_zero_termination() {
+    let input_seq = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    let result = new_ucmd!()
+        .arg("-z")
+        .arg("-i1-10")
+        .succeeds()
+        .no_stderr()
+        .stdout
+        .clone();
+
+    let mut result_seq: Vec<i32> = result
+        .split("\0")
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    result_seq.sort();
+    assert_eq!(result_seq, input_seq, "Output is not a permutation");
+}
+
+#[test]
+fn test_echo() {
+    let input_seq = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    let result = new_ucmd!()
+        .arg("-e")
+        .args(
+            &input_seq
+                .iter()
+                .map(|x| x.to_string())
+                .collect::<Vec<String>>(),
+        )
+        .succeeds()
+        .no_stderr()
+        .stdout
+        .clone();
+
+    let mut result_seq: Vec<i32> = result
+        .split("\n")
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    result_seq.sort();
+    assert_eq!(result_seq, input_seq, "Output is not a permutation");
+}
+
+#[test]
+fn test_head_count() {
+    let repeat_limit = 5;
+    let input_seq = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    let input = input_seq
+        .iter()
+        .map(|x| x.to_string())
+        .collect::<Vec<String>>()
+        .join("\n");
+
+    let result = new_ucmd!()
+        .args(&["-n", &repeat_limit.to_string()])
+        .pipe_in(input.as_bytes())
+        .succeeds()
+        .no_stderr()
+        .stdout
+        .clone();
+
+    let mut result_seq: Vec<i32> = result
+        .split("\n")
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    result_seq.sort();
+    assert_eq!(result_seq.len(), repeat_limit, "Output is not limited");
+    assert!(
+        result_seq.iter().all(|x| input_seq.contains(x)),
+        format!("Output includes element not from input: {}", result)
+    )
+}
+
+#[test]
+fn test_repeat() {
+    let repeat_limit = 15000;
+    let input_seq = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    let input = input_seq
+        .iter()
+        .map(|x| x.to_string())
+        .collect::<Vec<String>>()
+        .join("\n");
+
+    let result = new_ucmd!()
+        .arg("-r")
+        .args(&["-n", &repeat_limit.to_string()])
+        .pipe_in(input.as_bytes())
+        .succeeds()
+        .no_stderr()
+        .stdout
+        .clone();
+
+    let result_seq: Vec<i32> = result
+        .split("\n")
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    assert_eq!(
+        result_seq.len(),
+        repeat_limit,
+        "Output is not repeating forever"
+    );
+    assert!(
+        result_seq.iter().all(|x| input_seq.contains(x)),
+        format!(
+            "Output includes element not from input: {:?}",
+            result_seq
+                .iter()
+                .filter(|x| !input_seq.contains(x))
+                .collect::<Vec<&i32>>()
+        )
+    )
+}
+
+#[test]
+fn test_file_input() {
+    let expected_seq = vec![11, 12, 13, 14, 15, 16, 17, 18, 19, 20];
+
+    let result = new_ucmd!()
+        .arg("file_input.txt")
+        .succeeds()
+        .no_stderr()
+        .stdout
+        .clone();
+
+    let mut result_seq: Vec<i32> = result
+        .split("\n")
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    result_seq.sort();
+    assert_eq!(result_seq, expected_seq, "Output is not a permutation");
+}
+
 #[test]
 fn test_shuf_echo_and_input_range_not_allowed() {
     let result = new_ucmd!().args(&["-e", "0", "-i", "0-2"]).run();