quic tests: Verify sample length is 16 bytes.

Author: briansmith

tests/quic_tests.rs

@@ -68,6 +68,7 @@ fn test_sample_len(alg: &'static quic::Algorithm) {
     let key = quic::HeaderProtectionKey::new(alg, &key_data).unwrap();
 
     let sample_len = alg.sample_len();
+    assert_eq!(sample_len, 16); // For all currently-implemented algorithms
     let sample_data = vec![0u8; sample_len + 2];
 
     // Sample is the right size.