Add test to ensure arch output is not empty (#7523)

* Add test to ensure arch output is not empty

This test ensures that the output of the arch command is non-empty, which is a minimal expectation across all supported architectures.

This helps avoid regressions or edge cases where the command might unexpectedly return an empty string on unsupported or misconfigured platforms.

* Update tests/by-util/test_arch.rs

Co-authored-by: Daniel Hofstetter <daniel.hofstetter@42dh.com>

* Apply cargo fmt formatting

---------

Co-authored-by: Daniel Hofstetter <daniel.hofstetter@42dh.com>

tests/by-util/test_arch.rs

@@ -21,3 +21,12 @@ fn test_arch_help() {
 fn test_invalid_arg() {
     new_ucmd!().arg("--definitely-invalid").fails_with_code(1);
 }
+
+#[test]
+fn test_arch_output_is_not_empty() {
+    let result = new_ucmd!().succeeds();
+    assert!(
+        !result.stdout_str().trim().is_empty(),
+        "arch output was empty"
+    );
+}