test(cksum): add test for trailing spaces making an error

src/uucore/src/lib/features/checksum.rs

@@ -991,6 +991,19 @@ mod tests {
         // Test invalid checksum line
         let lines_invalid = vec!["invalid checksum line".to_string()];
         assert!(determine_regex(&lines_invalid).is_none());
+
+        // Test leading space before checksum line
+        let lines_algo_based_leading_space =
+            vec!["   MD5 (example.txt) = d41d8cd98f00b204e9800998ecf8427e".to_string()];
+        let res = determine_regex(&lines_algo_based_leading_space);
+        assert!(res.is_some());
+        assert_eq!(res.unwrap().0.as_str(), ALGO_BASED_REGEX);
+
+        // Test trailing space after checksum line (should fail)
+        let lines_algo_based_leading_space =
+            vec!["MD5 (example.txt) = d41d8cd98f00b204e9800998ecf8427e ".to_string()];
+        let res = determine_regex(&lines_algo_based_leading_space);
+        assert!(res.is_none());
     }
 
     #[test]

tests/by-util/test_cksum.rs

@@ -1402,3 +1402,26 @@ fn test_zero_single_file() {
         .succeeds()
         .stdout_is_fixture("zero_single_file.expected");
 }
+
+#[test]
+fn test_check_trailing_space_fails() {
+    // If a checksum line has trailing spaces after the digest,
+    // it shall be considered improperly formatted.
+
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+
+    at.write("foo", "foo-content\n");
+    at.write(
+        "CHECKSUM",
+        "SHA1 (foo) = 058ab38dd3603703b3a7063cf95dc51a4286b6fe    \n",
+    );
+
+    scene
+        .ucmd()
+        .arg("--check")
+        .arg("CHECKSUM")
+        .fails()
+        .no_stdout()
+        .stderr_contains("CHECKSUM: no properly formatted checksum lines found");
+}