SSZ (partially) handles Dicts

specs/core/0_fork-choice.md

@@ -163,5 +163,8 @@ def on_attestation(store: Store, attestation: Attestation) -> None:
     validate_indexed_attestation(state, indexed_attestation)
     for i in indexed_attestation.custody_bit_0_indices + indexed_attestation.custody_bit_1_indices:
         if i not in store.latest_targets or attestation.data.target_epoch > store.latest_targets[i].epoch:
-            store.latest_targets[i] = Target(attestation.data.target_epoch, attestation.data.target_root)
+            store.latest_targets[i] = Target(
+                epoch = attestation.data.target_epoch,
+                root = attestation.data.target_root,
+            )
 ```

test_libs/pyspec/eth2spec/test/test_fork_choice.py

@@ -10,41 +10,56 @@ from eth2spec.test.helpers.state import next_slot
 @with_all_phases
 @spec_state_test
 def test_basic(spec, state):
+     yield 'pre', state
+
     # Initialization
      store = spec.get_genesis_store(state)
+     blocks = []
      time = 100
      spec.on_tick(store, time)
      assert store.time == time
 
      # On receiving a block of `GENESIS_SLOT + 1` slot
-    block = build_empty_block_for_next_slot(state)
+     block = build_empty_block_for_next_slot(spec, state)
+     blocks.append(block)
      spec.on_block(store, block)
      assert store.blocks[signing_root(block)] == block
 
      # On receiving a block of next epoch
      store.time = time + spec.SECONDS_PER_SLOT * spec.SLOTS_PER_EPOCH
-    block = build_empty_block_for_next_slot(state)
+     block = build_empty_block_for_next_slot(spec, state)
      block.slot += spec.SLOTS_PER_EPOCH
+     blocks.append(block)
 
      spec.on_block(store, block)
      assert store.blocks[signing_root(block)] == block
+     yield 'blocks', blocks, List[spec.BeaconBlock]
 
      # TODO: add tests for justified_root and finalized_root
+     yield 'post', state
 
 
 @with_all_phases
 @spec_state_test
 def test_on_attestation(spec, state):
+     yield 'pre', state
+
      store = spec.get_genesis_store(state)
      time = 100
      spec.on_tick(store, time)
 
-    next_slot(state)
+     next_slot(spec, state)
 
-    attestation = get_valid_attestation(state, slot=1)
+     attestation = get_valid_attestation(spec, state, slot=1)
+     yield 'attestation', attestation
      indexed_attestation = spec.convert_to_indexed(state, attestation)
      spec.on_attestation(store, attestation)
      assert (
          store.latest_targets[indexed_attestation.custody_bit_0_indices[0]] ==
-        spec.Target(attestation.data.target_epoch, attestation.data.target_root)
+         spec.Target(
+              epoch = attestation.data.target_epoch,
+              root = attestation.data.target_root
           )
+     )
+
+     yield 'post', state

test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py

@@ -1,4 +1,4 @@
-from typing import List, Iterable, TypeVar, Type, NewType
+from typing import List, Iterable, TypeVar, Type, NewType, Dict
 from typing import Union
 from typing_inspect import get_origin
 
@@ -280,6 +280,32 @@ class Vector(metaclass=VectorMeta):
         return self.hash_tree_root() == other.hash_tree_root()
 
 
+# # Super Secret Un-documented SSZ Dict (for forkchoice)
+# # -----------------------------
+class Dict(dict):
+    def __init__(self,*args,**kwargs) : dict.__init__(self,*args,**kwargs) 
+
+    def serialize(self):
+        raise NotImplementedError
+
+    def hash_tree_root(self):
+        raise NotImplementedError
+
+    def __getitem__(self, key):
+        return self.items[key]
+
+    def __setitem__(self, key, value):
+        self.items[key] = value
+
+    def __iter__(self):
+        return iter(self.items)
+
+    def __len__(self):
+        return len(self.items)
+
+    def __eq__(self, other):
+        raise NotImplementedError
+
 # SSZ BytesN
 # -----------------------------
 
@@ -407,6 +433,8 @@ def get_zero_value(typ):
         return b''
     elif is_container_type(typ):
         return typ(**{f: get_zero_value(t) for f, t in typ.get_fields()})
+    elif is_dict_type(typ):
+        return dict()
     else:
         raise Exception("Type not supported: {}".format(typ))
 
@@ -498,6 +526,13 @@ def is_container_type(typ):
     return isinstance(typ, type) and issubclass(typ, Container)
 
 
+def is_dict_type(typ):
+    """
+    Check of the given type is a Dict. (Which are a part of the super-secret undocumented SSZ spec)
+    """
+    return get_origin(typ) is Dict or get_origin(typ) is dict
+
+
 T = TypeVar('T')
 L = TypeVar('L')