tests ~ reorganize tests

tests/by-util/test_seq.rs

@@ -0,0 +1,33 @@
+use crate::common::util::*;
+
+#[test]
+fn test_count_up() {
+    new_ucmd!()
+        .args(&["10"])
+        .run()
+        .stdout_is("1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n");
+}
+
+#[test]
+fn test_count_down() {
+    new_ucmd!()
+        .args(&["--", "5", "-1", "1"])
+        .run()
+        .stdout_is("5\n4\n3\n2\n1\n");
+}
+
+#[test]
+fn test_separator_and_terminator() {
+    new_ucmd!()
+        .args(&["-s", ",", "-t", "!", "2", "6"])
+        .run()
+        .stdout_is("2,3,4,5,6!");
+}
+
+#[test]
+fn test_equalize_widths() {
+    new_ucmd!()
+        .args(&["-w", "5", "10"])
+        .run()
+        .stdout_is("05\n06\n07\n08\n09\n10\n");
+}