diff --git a/tests/core/pyspec/eth2spec/test/helpers/shard_block.py b/tests/core/pyspec/eth2spec/test/helpers/shard_block.py
index 1193f05e5..c8d60938b 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/shard_block.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/shard_block.py
@@ -30,7 +30,7 @@ def build_shard_block(spec,
         slot = shard_parent_state.slot + 1
 
     if body is None:
-        body = get_sample_shard_block_body()
+        body = get_sample_shard_block_body(spec)
 
     beacon_state, beacon_parent_root = get_state_and_beacon_parent_root_at_slot(spec, beacon_state, slot)
     proposer_index = spec.get_shard_proposer_index(beacon_state, slot, shard)
@@ -83,5 +83,6 @@ def get_committee_index_of_shard(spec, state, slot, shard):  # Optional[Committe
     return None
 
 
-def get_sample_shard_block_body():
-    return b'\x56' * 128
+def get_sample_shard_block_body(spec, is_max=False):
+    size = spec.MAX_SHARD_BLOCK_SIZE if is_max else 128
+    return b'\x56' * size
diff --git a/tests/core/pyspec/eth2spec/test/phase1/block_processing/test_process_shard_transition.py b/tests/core/pyspec/eth2spec/test/phase1/block_processing/test_process_shard_transition.py
index 0c9293b74..afc4828f8 100644
--- a/tests/core/pyspec/eth2spec/test/phase1/block_processing/test_process_shard_transition.py
+++ b/tests/core/pyspec/eth2spec/test/phase1/block_processing/test_process_shard_transition.py
@@ -8,50 +8,63 @@ from eth2spec.test.helpers.shard_transitions import run_shard_transitions_proces
 from eth2spec.test.helpers.shard_block import (
     build_shard_block,
     get_shard_transitions,
+    get_sample_shard_block_body,
+    get_committee_index_of_shard,
 )
 from eth2spec.test.helpers.state import transition_to, transition_to_valid_shard_slot, next_slot
 
 
-def run_basic_crosslink_tests(spec, state, target_len_offset_slot, valid=True):
+def get_initial_env(spec, state, target_len_offset_slot):
     state = transition_to_valid_shard_slot(spec, state)
     committee_index = spec.CommitteeIndex(0)
+    target_shard_slot = state.slot + target_len_offset_slot - 1
+    shard = spec.compute_shard_from_committee_index(state, committee_index, target_shard_slot)
+    return state, shard, target_shard_slot
+
+
+def get_attestations_and_shard_transitions(spec, state, shard_block_dict):
+    shard_transitions = get_shard_transitions(spec, state, shard_block_dict)
+    attestations = [
+        get_valid_on_time_attestation(
+            spec, state,
+            index=get_committee_index_of_shard(spec, state, state.slot, shard),
+            shard_transition=shard_transition,
+            signed=False,
+        )
+        for shard, shard_transition in enumerate(shard_transitions)
+        if shard_transition != spec.ShardTransition()
+    ]
+    return attestations, shard_transitions
+
+
+def run_basic_crosslink_tests(spec, state, target_len_offset_slot, valid=True):
+    state, shard, target_shard_slot = get_initial_env(spec, state, target_len_offset_slot)
     init_slot = state.slot
-    shard_slot = init_slot + target_len_offset_slot - 1
-    shard = spec.compute_shard_from_committee_index(state, committee_index, shard_slot)
     assert state.shard_states[shard].slot == init_slot - 1
 
-    # Create SignedShardBlock
-    body = b'\x56' * spec.MAX_SHARD_BLOCK_SIZE
-    shard_block = build_shard_block(spec, state, shard, body=body, slot=state.slot, signed=True)
-    shard_blocks = [shard_block]
+    # Create SignedShardBlock at init_slot
+    shard_block = build_shard_block(
+        spec, state, shard,
+        slot=init_slot, body=get_sample_shard_block_body(spec, is_max=True), signed=True
+    )
+
+    # Transition state to target shard slot
+    transition_to(spec, state, target_shard_slot)
+
+    # Create a shard_transitions that would be included at beacon block `target_shard_slot + 1`
+    shard_block_dict = {shard: [shard_block]}
+    attestations, shard_transitions = get_attestations_and_shard_transitions(spec, state, shard_block_dict)
 
-    # Transition state latest shard slot
-    transition_to(spec, state, shard_slot)
-    # Create a shard_transitions that would be included at beacon block `state.slot + target_len_offset_slot`
-    shard_transitions = get_shard_transitions(
-        spec,
-        state,
-        shard_block_dict={shard: shard_blocks},
-    )
-    shard_transition = shard_transitions[shard]
-    attestation = get_valid_on_time_attestation(
-        spec,
-        state,
-        index=committee_index,
-        shard_transition=shard_transition,
-        signed=False,
-    )
     next_slot(spec, state)
     pre_gasprice = state.shard_states[shard].gasprice
 
-    transition_to(spec, state, init_slot + target_len_offset_slot)
     pre_shard_state = state.shard_states[shard]
-    yield from run_shard_transitions_processing(spec, state, shard_transitions, [attestation], valid=valid)
+    yield from run_shard_transitions_processing(spec, state, shard_transitions, attestations, valid=valid)
 
     if valid:
         shard_state = state.shard_states[shard]
         assert shard_state != pre_shard_state
-        assert shard_state == shard_transition.shard_states[len(shard_transition.shard_states) - 1]
+        assert shard_state == shard_transitions[shard].shard_states[len(shard_transitions[shard].shard_states) - 1]
         assert shard_state.latest_block_root == shard_block.message.hash_tree_root()
         if target_len_offset_slot == 1:
             assert shard_state.gasprice > pre_gasprice
@@ -69,3 +82,10 @@ def test_basic_crosslinks(spec, state):
 def test_multiple_offset_slots(spec, state):
     # NOTE: this test is only for full crosslink (minimal config), not for mainnet
     yield from run_basic_crosslink_tests(spec, state, target_len_offset_slot=2, valid=True)
+
+
+@with_all_phases_except([PHASE0])
+@spec_state_test
+def test_no_winning_root(spec, state):
+    # NOTE: this test is only for full crosslink (minimal config), not for mainnet
+    yield from run_basic_crosslink_tests(spec, state, target_len_offset_slot=1, valid=True)