test(hashsum): Improve tests for checking length validation errors for BLAKE2b

Author: RenjiSann

tests/by-util/test_hashsum.rs

@@ -3,6 +3,8 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
+use rstest::rstest;
+
 use uutests::new_ucmd;
 use uutests::util::TestScenario;
 use uutests::util_name;
@@ -250,21 +252,30 @@ fn test_invalid_b2sum_length_option_not_multiple_of_8() {
         .ccmd("b2sum")
         .arg("--length=9")
         .arg(at.subdir.join("testf"))
-        .fails_with_code(1);
+        .fails_with_code(1)
+        .stderr_contains("b2sum: invalid length: '9'")
+        .stderr_contains("b2sum: length is not a multiple of 8");
 }
 
-#[test]
-fn test_invalid_b2sum_length_option_too_large() {
+#[rstest]
+#[case("513")]
+#[case("1024")]
+#[case("18446744073709552000")]
+fn test_invalid_b2sum_length_option_too_large(#[case] len: &str) {
     let scene = TestScenario::new(util_name!());
     let at = &scene.fixtures;
 
     at.write("testf", "foobar\n");
 
     scene
         .ccmd("b2sum")
-        .arg("--length=513")
+        .arg("--length")
+        .arg(len)
         .arg(at.subdir.join("testf"))
-        .fails_with_code(1);
+        .fails_with_code(1)
+        .no_stdout()
+        .stderr_contains(format!("b2sum: invalid length: '{len}'"))
+        .stderr_contains("b2sum: maximum digest length for 'BLAKE2b' is 512 bits");
 }
 
 #[test]