diff --git a/tests/by-util/test_truncate.rs b/tests/by-util/test_truncate.rs
index 7bb171386..ce7964d57 100644
--- a/tests/by-util/test_truncate.rs
+++ b/tests/by-util/test_truncate.rs
@@ -14,6 +14,35 @@ fn test_increase_file_size() {
     assert!(file.seek(SeekFrom::Current(0)).unwrap() == 5 * 1024);
 }
 
+#[test]
+fn test_increase_file_size_kb() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let mut file = at.make_file(TFILE1);
+    ucmd.args(&["-s", "+5KB", TFILE1]).succeeds();
+
+    file.seek(SeekFrom::End(0)).unwrap();
+    assert!(file.seek(SeekFrom::Current(0)).unwrap() == 5 * 1000);
+}
+
+#[test]
+fn test_reference() {
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+    let mut file = at.make_file(TFILE2);
+
+    scene.ucmd().arg("-s").arg("+5KB").arg(TFILE1).run();
+
+    scene
+        .ucmd()
+        .arg("--reference")
+        .arg(TFILE1)
+        .arg(TFILE2)
+        .run();
+
+    file.seek(SeekFrom::End(0)).unwrap();
+    assert!(file.seek(SeekFrom::Current(0)).unwrap() == 5 * 1000);
+}
+
 #[test]
 fn test_decrease_file_size() {
     let (at, mut ucmd) = at_and_ucmd!();
@@ -23,3 +52,20 @@ fn test_decrease_file_size() {
     file.seek(SeekFrom::End(0)).unwrap();
     assert!(file.seek(SeekFrom::Current(0)).unwrap() == 6);
 }
+
+#[test]
+fn test_failed() {
+    new_ucmd!().fails();
+}
+
+#[test]
+fn test_failed_2() {
+    let (_at, mut ucmd) = at_and_ucmd!();
+    ucmd.args(&[TFILE1]).fails();
+}
+
+#[test]
+fn test_failed_incorrect_arg() {
+    let (_at, mut ucmd) = at_and_ucmd!();
+    ucmd.args(&["-s", "+5A", TFILE1]).fails();
+}