Refactor bucket storage bad header size test (#33091)

bucket_map/src/bucket_storage.rs

@@ -509,8 +509,15 @@ mod test {
         assert!(storage.is_free(ix));
     }
 
-    struct BucketBadHeader {}
+    #[test]
-
+    #[should_panic]
+    fn test_header_bad_size() {
+        struct BucketBadHeader;
+        impl BucketCapacity for BucketBadHeader {
+            fn capacity(&self) -> u64 {
+                unimplemented!();
+            }
+        }
         impl BucketOccupied for BucketBadHeader {
             fn occupy(&mut self, _element: &mut [u8], _ix: usize) {
                 unimplemented!();
@@ -525,22 +532,13 @@ mod test {
                 // not multiple of u64
                 std::mem::size_of::<u64>() - 1
             }
-        /// initialize this struct
             fn new(_num_elements: Capacity) -> Self {
-            Self {}
+                Self
             }
         }
 
-    impl BucketCapacity for BucketBadHeader {
+        // ensure we panic if the header size (i.e. offset to first data) is not aligned to eight bytes
-        fn capacity(&self) -> u64 {
+        BucketStorage::<BucketBadHeader>::new_with_capacity(
-            unimplemented!();
-        }
-    }
-
-    #[test]
-    #[should_panic(expected = "assertion failed: `(left == right)`")]
-    fn test_header_size() {
-        _ = BucketStorage::<BucketBadHeader>::new_with_capacity(
             Arc::default(),
             0,
             0,