fix: issue when changing default in smt

Author: antazoey

tests/test_smt.py

@@ -14,9 +14,12 @@
 @given(
     k=st.binary(min_size=1, max_size=32),
     v=st.binary(min_size=1, max_size=32),
+    default=st.binary(min_size=1, max_size=32),
 )
-def test_simple_kv(k, v):
-    smt = SparseMerkleTree(key_size=len(k))
+def test_simple_kv(k, v, default):
+    # default must be different than v
+    default = BLANK_NODE if default == v else default
+    smt = SparseMerkleTree(key_size=len(k), default=default)
     empty_root = smt.root_hash
 
     # Nothing has been added yet

trie/smt.py

@@ -252,7 +252,7 @@ def get(self, key: bytes) -> bytes:
         value, _ = self._get(key)
 
         # Ensure that it isn't blank!
-        if value == BLANK_NODE:
+        if value == self._default:
             raise KeyError("Key does not exist")
 
         return value
@@ -261,7 +261,7 @@ def branch(self, key: bytes) -> Tuple[Hash32]:
         value, branch = self._get(key)
 
         # Ensure that it isn't blank!
-        if value == BLANK_NODE:
+        if value == self._default:
             raise KeyError("Key does not exist")
 
         return branch