From e341f4e1f858ac678ab9f9c052b01588d67612cc Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Tue, 31 Aug 2021 12:45:47 -0700
Subject: [PATCH 01/14] refactor "leaking patch" helper

---
 .../pyspec/eth2spec/test/helpers/random.py    | 30 +++++++++++++++++++
 .../test/utils/randomized_block_tests.py      | 19 ++----------
 2 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/tests/core/pyspec/eth2spec/test/helpers/random.py b/tests/core/pyspec/eth2spec/test/helpers/random.py
index 8f095aebb..0bb2a6672 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/random.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/random.py
@@ -128,3 +128,33 @@ def randomize_state(spec, state, rng=Random(8020), exit_fraction=None, slash_fra
     exit_random_validators(spec, state, rng, fraction=exit_fraction)
     slash_random_validators(spec, state, rng, fraction=slash_fraction)
     randomize_attestation_participation(spec, state, rng)
+
+
+def patch_state_to_non_leaking(spec, state):
+    """
+    This function performs an irregular state transition so that:
+    1. the current justified checkpoint references the previous epoch
+    2. the previous justified checkpoint references the epoch before previous
+    3. the finalized checkpoint matches the previous justified checkpoint
+
+    The effects of this function are intended to offset randomization side effects
+    performed by other functionality in this module so that if the ``state`` was leaking,
+    then the ``state`` is not leaking after.
+    """
+    state.justification_bits = (True, True, True, True)
+    previous_epoch = spec.get_previous_epoch(state)
+    previous_root = spec.get_block_root(state, previous_epoch)
+    previous_previous_epoch = max(spec.GENESIS_EPOCH, spec.Epoch(previous_epoch - 1))
+    previous_previous_root = spec.get_block_root(state, previous_previous_epoch)
+    state.previous_justified_checkpoint = spec.Checkpoint(
+        epoch=previous_previous_epoch,
+        root=previous_previous_root,
+    )
+    state.current_justified_checkpoint = spec.Checkpoint(
+        epoch=previous_epoch,
+        root=previous_root,
+    )
+    state.finalized_checkpoint = spec.Checkpoint(
+        epoch=previous_previous_epoch,
+        root=previous_previous_root,
+    )
diff --git a/tests/core/pyspec/eth2spec/test/utils/randomized_block_tests.py b/tests/core/pyspec/eth2spec/test/utils/randomized_block_tests.py
index ce99c1053..02a5464f7 100644
--- a/tests/core/pyspec/eth2spec/test/utils/randomized_block_tests.py
+++ b/tests/core/pyspec/eth2spec/test/utils/randomized_block_tests.py
@@ -17,6 +17,7 @@ from eth2spec.test.helpers.inactivity_scores import (
 )
 from eth2spec.test.helpers.random import (
     randomize_state as randomize_state_helper,
+    patch_state_to_non_leaking,
 )
 from eth2spec.test.helpers.state import (
     next_slot,
@@ -274,23 +275,7 @@ def _randomized_scenario_setup(state_randomizer):
         may not reflect this condition with prior (arbitrary) mutations,
         so this mutator addresses that fact.
         """
-        state.justification_bits = (True, True, True, True)
-        previous_epoch = spec.get_previous_epoch(state)
-        previous_root = spec.get_block_root(state, previous_epoch)
-        previous_previous_epoch = max(spec.GENESIS_EPOCH, spec.Epoch(previous_epoch - 1))
-        previous_previous_root = spec.get_block_root(state, previous_previous_epoch)
-        state.previous_justified_checkpoint = spec.Checkpoint(
-            epoch=previous_previous_epoch,
-            root=previous_previous_root,
-        )
-        state.current_justified_checkpoint = spec.Checkpoint(
-            epoch=previous_epoch,
-            root=previous_root,
-        )
-        state.finalized_checkpoint = spec.Checkpoint(
-            epoch=previous_previous_epoch,
-            root=previous_previous_root,
-        )
+        patch_state_to_non_leaking(spec, state)
 
     return (
         # NOTE: the block randomization function assumes at least 1 shard committee period

From 7cb5901ee62d2ec99ff05537c079db2d3f055402 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Tue, 31 Aug 2021 12:46:00 -0700
Subject: [PATCH 02/14] add spec test case for rewards with exited validators
 and _no_ leak

---
 tests/core/pyspec/eth2spec/test/helpers/rewards.py | 14 +++++++++++++-
 .../eth2spec/test/phase0/rewards/test_random.py    | 12 ++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/tests/core/pyspec/eth2spec/test/helpers/rewards.py b/tests/core/pyspec/eth2spec/test/helpers/rewards.py
index 1867db08f..ec617bda9 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/rewards.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/rewards.py
@@ -255,7 +255,19 @@ def run_get_inactivity_penalty_deltas(spec, state):
                 else:
                     assert penalties[index] > base_penalty
         else:
-            assert penalties[index] == 0
+            if not is_post_altair(spec):
+                assert penalties[index] == 0
+                continue
+            else:
+                # post altair, this penalty is derived from the inactivity score
+                # regardless if the state is leaking or not...
+                if index in matching_attesting_indices:
+                    assert penalties[index] == 0
+                else:
+                    # copied from spec:
+                    penalty_numerator = state.validators[index].effective_balance * state.inactivity_scores[index]
+                    penalty_denominator = spec.config.INACTIVITY_SCORE_BIAS * spec.INACTIVITY_PENALTY_QUOTIENT_ALTAIR
+                    assert penalties[index] == penalty_numerator // penalty_denominator
 
 
 def transition_state_to_leak(spec, state, epochs=None):
diff --git a/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py b/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
index 1184a6617..78c6846ae 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
@@ -9,6 +9,7 @@ from eth2spec.test.context import (
     low_balances, misc_balances,
 )
 import eth2spec.test.helpers.rewards as rewards_helpers
+from eth2spec.test.helpers.random import randomize_state, patch_state_to_non_leaking
 
 
 @with_all_phases
@@ -57,3 +58,14 @@ def test_full_random_low_balances_1(spec, state):
 @single_phase
 def test_full_random_misc_balances(spec, state):
     yield from rewards_helpers.run_test_full_random(spec, state, rng=Random(7070))
+
+
+@with_all_phases
+@spec_state_test
+def test_full_random_without_leak_0(spec, state):
+    rng = Random(1010)
+    randomize_state(spec, state, rng)
+    assert spec.is_in_inactivity_leak(state)
+    patch_state_to_non_leaking(spec, state)
+    assert not spec.is_in_inactivity_leak(state)
+    yield from rewards_helpers.run_deltas(spec, state)

From cf23cd00ab2c5bf4fe5addfed5df1be06402bf2a Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Wed, 1 Sep 2021 14:38:02 -0700
Subject: [PATCH 03/14] ensure the test covers exited, unslashed validators

---
 tests/core/pyspec/eth2spec/test/helpers/voluntary_exits.py | 7 +++++++
 .../pyspec/eth2spec/test/phase0/rewards/test_random.py     | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/tests/core/pyspec/eth2spec/test/helpers/voluntary_exits.py b/tests/core/pyspec/eth2spec/test/helpers/voluntary_exits.py
index 73d4598b3..55ea0b5b0 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/voluntary_exits.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/voluntary_exits.py
@@ -34,6 +34,13 @@ def get_exited_validators(spec, state):
     return [index for (index, validator) in enumerate(state.validators) if validator.exit_epoch <= current_epoch]
 
 
+def get_unslashed_exited_validators(spec, state):
+    return [
+        index for index in get_exited_validators(spec, state)
+        if not state.validators[index].slashed
+    ]
+
+
 def exit_validators(spec, state, validator_count, rng=None):
     if rng is None:
         rng = Random(1337)
diff --git a/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py b/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
index 78c6846ae..f158f3cf8 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
@@ -10,6 +10,7 @@ from eth2spec.test.context import (
 )
 import eth2spec.test.helpers.rewards as rewards_helpers
 from eth2spec.test.helpers.random import randomize_state, patch_state_to_non_leaking
+from eth2spec.test.helpers.voluntary_exits import get_unslashed_exited_validators
 
 
 @with_all_phases
@@ -68,4 +69,6 @@ def test_full_random_without_leak_0(spec, state):
     assert spec.is_in_inactivity_leak(state)
     patch_state_to_non_leaking(spec, state)
     assert not spec.is_in_inactivity_leak(state)
+    target_validators = get_unslashed_exited_validators(spec, state)
+    assert len(target_validators) != 0
     yield from rewards_helpers.run_deltas(spec, state)

From 0cc5f9cd59369ead4088b07580817fb66a5fc6e0 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Wed, 1 Sep 2021 14:43:11 -0700
Subject: [PATCH 04/14] modify helper for more precision on exited validators

---
 tests/core/pyspec/eth2spec/test/helpers/state.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/core/pyspec/eth2spec/test/helpers/state.py b/tests/core/pyspec/eth2spec/test/helpers/state.py
index b4c9e1d67..d8fda3754 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/state.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/state.py
@@ -1,6 +1,6 @@
 from eth2spec.test.context import expect_assertion_error, is_post_altair
 from eth2spec.test.helpers.block import apply_empty_block, sign_block, transition_unsigned_block
-from eth2spec.test.helpers.voluntary_exits import get_exited_validators
+from eth2spec.test.helpers.voluntary_exits import get_unslashed_exited_validators
 
 
 def get_balance(state, index):
@@ -142,7 +142,7 @@ def ensure_state_has_validators_across_lifecycle(spec, state):
     for each of the following lifecycle states:
         1. Pending / deposited
         2. Active
-        3. Exited
+        3. Exited (but not slashed)
         4. Slashed
     """
     has_pending = any(filter(spec.is_eligible_for_activation_queue, state.validators))
@@ -150,7 +150,7 @@ def ensure_state_has_validators_across_lifecycle(spec, state):
     current_epoch = spec.get_current_epoch(state)
     has_active = any(filter(lambda v: spec.is_active_validator(v, current_epoch), state.validators))
 
-    has_exited = any(get_exited_validators(spec, state))
+    has_exited = any(get_unslashed_exited_validators(spec, state))
 
     has_slashed = any(filter(lambda v: v.slashed, state.validators))
 

From 58c0da9059844e879593f2aff5ee081d01587c01 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Wed, 1 Sep 2021 14:44:06 -0700
Subject: [PATCH 05/14] ensure rewards spec test with exited validators

---
 .../eth2spec/test/phase0/rewards/test_random.py    | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py b/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
index f158f3cf8..68a6a3279 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
@@ -37,6 +37,20 @@ def test_full_random_3(spec, state):
     yield from rewards_helpers.run_test_full_random(spec, state, rng=Random(4040))
 
 
+@with_all_phases
+@spec_state_test
+def test_full_random_4(spec, state):
+    """
+    Ensure a rewards test with some exited (but not slashed) validators.
+    """
+    rng = Random(5050)
+    randomize_state(spec, state, rng)
+    assert spec.is_in_inactivity_leak(state)
+    target_validators = get_unslashed_exited_validators(spec, state)
+    assert len(target_validators) != 0
+    yield from rewards_helpers.run_deltas(spec, state)
+
+
 @with_all_phases
 @with_custom_state(balances_fn=low_balances, threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
 @spec_test

From df8976377736c2d9121cb63454345cdb6011eaa0 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Wed, 1 Sep 2021 15:46:40 -0700
Subject: [PATCH 06/14] ensure balance differential as a sanity check

---
 tests/core/pyspec/eth2spec/test/helpers/state.py     | 12 ++++++++++++
 .../eth2spec/test/phase0/rewards/test_random.py      |  3 +++
 2 files changed, 15 insertions(+)

diff --git a/tests/core/pyspec/eth2spec/test/helpers/state.py b/tests/core/pyspec/eth2spec/test/helpers/state.py
index d8fda3754..327bebaf8 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/state.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/state.py
@@ -155,3 +155,15 @@ def ensure_state_has_validators_across_lifecycle(spec, state):
     has_slashed = any(filter(lambda v: v.slashed, state.validators))
 
     return has_pending and has_active and has_exited and has_slashed
+
+
+def has_active_balance_differential(spec, state):
+    """
+    Ensure there is a difference between the total balance of
+    all _active_ validators and _all_ validators.
+    """
+    epoch = spec.get_current_epoch(state)
+    active_indices = spec.get_active_validator_indices(state, epoch)
+    active_balance = spec.get_total_balance(state, set(active_indices))
+    total_balance = spec.get_total_balance(state, set(range(len(state.validators))))
+    return active_balance // spec.EFFECTIVE_BALANCE_INCREMENT != total_balance // spec.EFFECTIVE_BALANCE_INCREMENT
diff --git a/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py b/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
index 68a6a3279..44f22270b 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/rewards/test_random.py
@@ -10,6 +10,7 @@ from eth2spec.test.context import (
 )
 import eth2spec.test.helpers.rewards as rewards_helpers
 from eth2spec.test.helpers.random import randomize_state, patch_state_to_non_leaking
+from eth2spec.test.helpers.state import has_active_balance_differential
 from eth2spec.test.helpers.voluntary_exits import get_unslashed_exited_validators
 
 
@@ -48,6 +49,7 @@ def test_full_random_4(spec, state):
     assert spec.is_in_inactivity_leak(state)
     target_validators = get_unslashed_exited_validators(spec, state)
     assert len(target_validators) != 0
+    assert has_active_balance_differential(spec, state)
     yield from rewards_helpers.run_deltas(spec, state)
 
 
@@ -85,4 +87,5 @@ def test_full_random_without_leak_0(spec, state):
     assert not spec.is_in_inactivity_leak(state)
     target_validators = get_unslashed_exited_validators(spec, state)
     assert len(target_validators) != 0
+    assert has_active_balance_differential(spec, state)
     yield from rewards_helpers.run_deltas(spec, state)

From ad076697f424a84c0e9b07e1d9316c3cd5906ee6 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Wed, 1 Sep 2021 15:47:05 -0700
Subject: [PATCH 07/14] add test case for active/exited difference for sync
 rewards processing

---
 .../test_process_sync_aggregate.py            | 21 +++----
 .../test_process_sync_aggregate_random.py     | 62 ++++++++++++++++---
 .../eth2spec/test/helpers/sync_committee.py   | 26 ++------
 3 files changed, 67 insertions(+), 42 deletions(-)

diff --git a/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate.py b/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate.py
index bd52ce727..0eaddbb88 100644
--- a/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate.py
+++ b/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate.py
@@ -12,7 +12,6 @@ from eth2spec.test.helpers.constants import (
 from eth2spec.test.helpers.sync_committee import (
     compute_aggregate_sync_committee_signature,
     compute_committee_indices,
-    get_committee_indices,
     run_sync_committee_processing,
     run_successful_sync_committee_test,
 )
@@ -28,7 +27,7 @@ from eth2spec.test.context import (
 @spec_state_test
 @always_bls
 def test_invalid_signature_bad_domain(spec, state):
-    committee_indices = compute_committee_indices(spec, state, state.current_sync_committee)
+    committee_indices = compute_committee_indices(spec, state)
 
     block = build_empty_block_for_next_slot(spec, state)
     block.body.sync_aggregate = spec.SyncAggregate(
@@ -48,7 +47,7 @@ def test_invalid_signature_bad_domain(spec, state):
 @spec_state_test
 @always_bls
 def test_invalid_signature_missing_participant(spec, state):
-    committee_indices = compute_committee_indices(spec, state, state.current_sync_committee)
+    committee_indices = compute_committee_indices(spec, state)
     rng = random.Random(2020)
     random_participant = rng.choice(committee_indices)
 
@@ -111,7 +110,7 @@ def test_invalid_signature_infinite_signature_with_single_participant(spec, stat
 @spec_state_test
 @always_bls
 def test_invalid_signature_extra_participant(spec, state):
-    committee_indices = compute_committee_indices(spec, state, state.current_sync_committee)
+    committee_indices = compute_committee_indices(spec, state)
     rng = random.Random(3030)
     random_participant = rng.choice(committee_indices)
 
@@ -134,7 +133,7 @@ def test_invalid_signature_extra_participant(spec, state):
 @with_presets([MINIMAL], reason="to create nonduplicate committee")
 @spec_state_test
 def test_sync_committee_rewards_nonduplicate_committee(spec, state):
-    committee_indices = get_committee_indices(spec, state, duplicates=False)
+    committee_indices = compute_committee_indices(spec, state)
     committee_size = len(committee_indices)
     committee_bits = [True] * committee_size
     active_validator_count = len(spec.get_active_validator_indices(state, spec.get_current_epoch(state)))
@@ -150,7 +149,7 @@ def test_sync_committee_rewards_nonduplicate_committee(spec, state):
 @with_presets([MAINNET], reason="to create duplicate committee")
 @spec_state_test
 def test_sync_committee_rewards_duplicate_committee_no_participation(spec, state):
-    committee_indices = get_committee_indices(spec, state, duplicates=True)
+    committee_indices = compute_committee_indices(spec, state)
     committee_size = len(committee_indices)
     committee_bits = [False] * committee_size
     active_validator_count = len(spec.get_active_validator_indices(state, spec.get_current_epoch(state)))
@@ -166,7 +165,7 @@ def test_sync_committee_rewards_duplicate_committee_no_participation(spec, state
 @with_presets([MAINNET], reason="to create duplicate committee")
 @spec_state_test
 def test_sync_committee_rewards_duplicate_committee_half_participation(spec, state):
-    committee_indices = get_committee_indices(spec, state, duplicates=True)
+    committee_indices = compute_committee_indices(spec, state)
     committee_size = len(committee_indices)
     committee_bits = [True] * (committee_size // 2) + [False] * (committee_size // 2)
     assert len(committee_bits) == committee_size
@@ -183,7 +182,7 @@ def test_sync_committee_rewards_duplicate_committee_half_participation(spec, sta
 @with_presets([MAINNET], reason="to create duplicate committee")
 @spec_state_test
 def test_sync_committee_rewards_duplicate_committee_full_participation(spec, state):
-    committee_indices = get_committee_indices(spec, state, duplicates=True)
+    committee_indices = compute_committee_indices(spec, state)
     committee_size = len(committee_indices)
     committee_bits = [True] * committee_size
     active_validator_count = len(spec.get_active_validator_indices(state, spec.get_current_epoch(state)))
@@ -199,7 +198,7 @@ def test_sync_committee_rewards_duplicate_committee_full_participation(spec, sta
 @spec_state_test
 @always_bls
 def test_sync_committee_rewards_not_full_participants(spec, state):
-    committee_indices = compute_committee_indices(spec, state, state.current_sync_committee)
+    committee_indices = compute_committee_indices(spec, state)
     rng = random.Random(1010)
     committee_bits = [rng.choice([True, False]) for _ in committee_indices]
 
@@ -210,7 +209,7 @@ def test_sync_committee_rewards_not_full_participants(spec, state):
 @spec_state_test
 @always_bls
 def test_sync_committee_rewards_empty_participants(spec, state):
-    committee_indices = compute_committee_indices(spec, state, state.current_sync_committee)
+    committee_indices = compute_committee_indices(spec, state)
     committee_bits = [False for _ in committee_indices]
 
     yield from run_successful_sync_committee_test(spec, state, committee_indices, committee_bits)
@@ -220,7 +219,7 @@ def test_sync_committee_rewards_empty_participants(spec, state):
 @spec_state_test
 @always_bls
 def test_invalid_signature_past_block(spec, state):
-    committee_indices = compute_committee_indices(spec, state, state.current_sync_committee)
+    committee_indices = compute_committee_indices(spec, state)
 
     for _ in range(2):
         # NOTE: need to transition twice to move beyond the degenerate case at genesis
diff --git a/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py b/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py
index 75845e060..436e4d04b 100644
--- a/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py
+++ b/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py
@@ -2,10 +2,19 @@ import random
 from eth2spec.test.helpers.constants import (
     MAINNET, MINIMAL,
 )
+from eth2spec.test.helpers.random import (
+    randomize_state
+)
+from eth2spec.test.helpers.state import (
+    has_active_balance_differential,
+)
 from eth2spec.test.helpers.sync_committee import (
-    get_committee_indices,
+    compute_committee_indices,
     run_successful_sync_committee_test,
 )
+from eth2spec.test.helpers.voluntary_exits import (
+    get_unslashed_exited_validators,
+)
 from eth2spec.test.context import (
     with_altair_and_later,
     spec_state_test,
@@ -18,8 +27,8 @@ from eth2spec.test.context import (
 )
 
 
-def _test_harness_for_randomized_test_case(spec, state, duplicates=False, participation_fn=None):
-    committee_indices = get_committee_indices(spec, state, duplicates=duplicates)
+def _test_harness_for_randomized_test_case(spec, state, expect_duplicates=False, participation_fn=None):
+    committee_indices = compute_committee_indices(spec, state, state.current_sync_committee)
 
     if participation_fn:
         participating_indices = participation_fn(committee_indices)
@@ -28,7 +37,7 @@ def _test_harness_for_randomized_test_case(spec, state, duplicates=False, partic
 
     committee_bits = [index in participating_indices for index in committee_indices]
     committee_size = len(committee_indices)
-    if duplicates:
+    if expect_duplicates:
         assert committee_size > len(set(committee_indices))
     else:
         assert committee_size == len(set(committee_indices))
@@ -44,7 +53,7 @@ def test_random_only_one_participant_with_duplicates(spec, state):
     yield from _test_harness_for_randomized_test_case(
         spec,
         state,
-        duplicates=True,
+        expect_duplicates=True,
         participation_fn=lambda comm: [rng.choice(comm)],
     )
 
@@ -57,7 +66,7 @@ def test_random_low_participation_with_duplicates(spec, state):
     yield from _test_harness_for_randomized_test_case(
         spec,
         state,
-        duplicates=True,
+        expect_duplicates=True,
         participation_fn=lambda comm: rng.sample(comm, int(len(comm) * 0.25)),
     )
 
@@ -70,7 +79,7 @@ def test_random_high_participation_with_duplicates(spec, state):
     yield from _test_harness_for_randomized_test_case(
         spec,
         state,
-        duplicates=True,
+        expect_duplicates=True,
         participation_fn=lambda comm: rng.sample(comm, int(len(comm) * 0.75)),
     )
 
@@ -83,7 +92,7 @@ def test_random_all_but_one_participating_with_duplicates(spec, state):
     yield from _test_harness_for_randomized_test_case(
         spec,
         state,
-        duplicates=True,
+        expect_duplicates=True,
         participation_fn=lambda comm: rng.sample(comm, len(comm) - 1),
     )
 
@@ -98,7 +107,25 @@ def test_random_misc_balances_and_half_participation_with_duplicates(spec, state
     yield from _test_harness_for_randomized_test_case(
         spec,
         state,
-        duplicates=True,
+        expect_duplicates=True,
+        participation_fn=lambda comm: rng.sample(comm, len(comm) // 2),
+    )
+
+
+@with_altair_and_later
+@with_presets([MAINNET], reason="to create duplicate committee")
+@spec_state_test
+@single_phase
+def test_random_with_exits_with_duplicates(spec, state):
+    rng = random.Random(1402)
+    randomize_state(spec, state, rng=rng, exit_fraction=0.1, slash_fraction=0.0)
+    target_validators = get_unslashed_exited_validators(spec, state)
+    assert len(target_validators) != 0
+    assert has_active_balance_differential(spec, state)
+    yield from _test_harness_for_randomized_test_case(
+        spec,
+        state,
+        expect_duplicates=True,
         participation_fn=lambda comm: rng.sample(comm, len(comm) // 2),
     )
 
@@ -163,3 +190,20 @@ def test_random_misc_balances_and_half_participation_without_duplicates(spec, st
         state,
         participation_fn=lambda comm: rng.sample(comm, len(comm) // 2),
     )
+
+
+@with_altair_and_later
+@with_presets([MINIMAL], reason="to create nonduplicate committee")
+@spec_state_test
+@single_phase
+def test_random_with_exits_without_duplicates(spec, state):
+    rng = random.Random(1502)
+    randomize_state(spec, state, rng=rng, exit_fraction=0.1, slash_fraction=0.0)
+    target_validators = get_unslashed_exited_validators(spec, state)
+    assert len(target_validators) != 0
+    assert has_active_balance_differential(spec, state)
+    yield from _test_harness_for_randomized_test_case(
+        spec,
+        state,
+        participation_fn=lambda comm: rng.sample(comm, len(comm) // 2),
+    )
diff --git a/tests/core/pyspec/eth2spec/test/helpers/sync_committee.py b/tests/core/pyspec/eth2spec/test/helpers/sync_committee.py
index e59f679e1..417802ece 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/sync_committee.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/sync_committee.py
@@ -9,7 +9,6 @@ from eth2spec.test.helpers.block import (
 )
 from eth2spec.test.helpers.block_processing import run_block_processing_to
 from eth2spec.utils import bls
-from eth2spec.utils.hash_function import hash
 
 
 def compute_sync_committee_signature(spec, state, slot, privkey, block_root=None, domain_type=None):
@@ -75,10 +74,12 @@ def compute_sync_committee_proposer_reward(spec, state, committee_indices, commi
     return spec.Gwei(participant_reward * participant_number)
 
 
-def compute_committee_indices(spec, state, committee):
+def compute_committee_indices(spec, state, committee=None):
     """
     Given a ``committee``, calculate and return the related indices
     """
+    if committee is None:
+        committee = state.current_sync_committee
     all_pubkeys = [v.pubkey for v in state.validators]
     return [all_pubkeys.index(pubkey) for pubkey in committee.pubkeys]
 
@@ -153,6 +154,7 @@ def _build_block_for_next_slot_with_sync_participation(spec, state, committee_in
             state,
             block.slot - 1,
             [index for index, bit in zip(committee_indices, committee_bits) if bit],
+            block_root=block.parent_root,
         )
     )
     return block
@@ -161,23 +163,3 @@ def _build_block_for_next_slot_with_sync_participation(spec, state, committee_in
 def run_successful_sync_committee_test(spec, state, committee_indices, committee_bits):
     block = _build_block_for_next_slot_with_sync_participation(spec, state, committee_indices, committee_bits)
     yield from run_sync_committee_processing(spec, state, block)
-
-
-def get_committee_indices(spec, state, duplicates=False):
-    """
-    This utility function allows the caller to ensure there are or are not
-    duplicate validator indices in the returned committee based on
-    the boolean ``duplicates``.
-    """
-    state = state.copy()
-    current_epoch = spec.get_current_epoch(state)
-    randao_index = (current_epoch + 1) % spec.EPOCHS_PER_HISTORICAL_VECTOR
-    while True:
-        committee = spec.get_next_sync_committee_indices(state)
-        if duplicates:
-            if len(committee) != len(set(committee)):
-                return committee
-        else:
-            if len(committee) == len(set(committee)):
-                return committee
-        state.randao_mixes[randao_index] = hash(state.randao_mixes[randao_index])

From bd38587a1e4491f66174a7bc7314e17f34c53e8e Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Wed, 1 Sep 2021 15:53:08 -0700
Subject: [PATCH 08/14] add active/exited balances test for `process_slashings`

---
 .../test_process_slashings.py                 | 49 +++++++++++++++++--
 1 file changed, 44 insertions(+), 5 deletions(-)

diff --git a/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_slashings.py b/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_slashings.py
index e336ebef7..1b977640d 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_slashings.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_slashings.py
@@ -1,7 +1,11 @@
+from random import Random
 from eth2spec.test.context import spec_state_test, with_all_phases, is_post_altair
 from eth2spec.test.helpers.epoch_processing import (
     run_epoch_processing_with, run_epoch_processing_to
 )
+from eth2spec.test.helpers.random import randomize_state
+from eth2spec.test.helpers.state import has_active_balance_differential
+from eth2spec.test.helpers.voluntary_exits import get_unslashed_exited_validators
 from eth2spec.test.helpers.state import next_epoch
 
 
@@ -22,6 +26,9 @@ def slash_validators(spec, state, indices, out_epochs):
         spec.get_current_epoch(state) % spec.EPOCHS_PER_SLASHINGS_VECTOR
     ] = total_slashed_balance
 
+    # verify some slashings happened...
+    assert total_slashed_balance != 0
+
 
 def get_slashing_multiplier(spec):
     if is_post_altair(spec):
@@ -30,9 +37,7 @@ def get_slashing_multiplier(spec):
         return spec.PROPORTIONAL_SLASHING_MULTIPLIER
 
 
-@with_all_phases
-@spec_state_test
-def test_max_penalties(spec, state):
+def _setup_process_slashings_test(spec, state, not_slashable_set=set()):
     # Slashed count to ensure that enough validators are slashed to induce maximum penalties
     slashed_count = min(
         (len(state.validators) // get_slashing_multiplier(spec)) + 1,
@@ -41,14 +46,23 @@ def test_max_penalties(spec, state):
     )
     out_epoch = spec.get_current_epoch(state) + (spec.EPOCHS_PER_SLASHINGS_VECTOR // 2)
 
-    slashed_indices = list(range(slashed_count))
-    slash_validators(spec, state, slashed_indices, [out_epoch] * slashed_count)
+    eligible_indices = set(range(slashed_count))
+    slashed_indices = eligible_indices.difference(not_slashable_set)
+    slash_validators(spec, state, sorted(slashed_indices), [out_epoch] * slashed_count)
 
     total_balance = spec.get_total_active_balance(state)
     total_penalties = sum(state.slashings)
 
     assert total_balance // get_slashing_multiplier(spec) <= total_penalties
 
+    return slashed_indices
+
+
+@with_all_phases
+@spec_state_test
+def test_max_penalties(spec, state):
+    slashed_indices = _setup_process_slashings_test(spec, state)
+
     yield from run_process_slashings(spec, state)
 
     for i in slashed_indices:
@@ -171,3 +185,28 @@ def test_scaled_penalties(spec, state):
             * spec.EFFECTIVE_BALANCE_INCREMENT
         )
         assert state.balances[i] == pre_slash_balances[i] - expected_penalty
+
+
+@with_all_phases
+@spec_state_test
+def test_slashings_with_random_state(spec, state):
+    rng = Random(9998)
+    randomize_state(spec, state, rng)
+
+    pre_balances = state.balances.copy()
+
+    target_validators = get_unslashed_exited_validators(spec, state)
+    assert len(target_validators) != 0
+    assert has_active_balance_differential(spec, state)
+
+    slashed_indices = _setup_process_slashings_test(spec, state, not_slashable_set=target_validators)
+
+    # ensure no accidental slashings of protected set...
+    current_target_validators = get_unslashed_exited_validators(spec, state)
+    assert len(current_target_validators) != 0
+    assert current_target_validators == target_validators
+
+    yield from run_process_slashings(spec, state)
+
+    for i in slashed_indices:
+        assert state.balances[i] < pre_balances[i]

From d834b6e800eacea1961682e5abad701c5fb17c34 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Thu, 2 Sep 2021 12:37:11 -0700
Subject: [PATCH 09/14] add active/exited balances test for justification

---
 ..._process_justification_and_finalization.py | 76 ++++++++++++++++++-
 1 file changed, 75 insertions(+), 1 deletion(-)

diff --git a/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py b/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py
index 9db6076f8..1dfc07188 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py
@@ -1,8 +1,10 @@
+from random import Random
 from eth2spec.test.context import is_post_altair, spec_state_test, with_all_phases
 from eth2spec.test.helpers.epoch_processing import (
     run_epoch_processing_with,
 )
-from eth2spec.test.helpers.state import transition_to
+from eth2spec.test.helpers.state import transition_to, next_epoch_via_block, next_slot
+from eth2spec.test.helpers.voluntary_exits import get_unslashed_exited_validators
 
 
 def run_process_just_and_fin(spec, state):
@@ -300,3 +302,75 @@ def test_12_ok_support_messed_target(spec, state):
 @spec_state_test
 def test_12_poor_support(spec, state):
     yield from finalize_on_12(spec, state, 3, False, False)
+
+
+@with_all_phases
+@spec_state_test
+def test_balance_threshold_with_exited_validators(spec, state):
+    """
+    This test exercises a very specific failure mode where
+    exited validators are incorrectly included in the total active balance
+    when weighing justification.
+    """
+    rng = Random(133333)
+    # move past genesis conditions
+    for _ in range(3):
+        next_epoch_via_block(spec, state)
+
+    # mock attestation helper requires last slot of epoch
+    for _ in range(spec.SLOTS_PER_EPOCH - 1):
+        next_slot(spec, state)
+
+    # Step 1: Exit ~1/2 vals in current epoch
+    epoch = spec.get_current_epoch(state)
+    for index in spec.get_active_validator_indices(state, epoch):
+        if rng.choice([True, False]):
+            continue
+
+        validator = state.validators[index]
+        validator.exit_epoch = epoch
+        validator.withdrawable_epoch = epoch + 1
+
+    exited_validators = get_unslashed_exited_validators(spec, state)
+    assert len(exited_validators) != 0
+
+    source = state.current_justified_checkpoint
+    target = spec.Checkpoint(
+        epoch=epoch,
+        root=spec.get_block_root(state, epoch)
+    )
+    add_mock_attestations(
+        spec,
+        state,
+        epoch,
+        source,
+        target,
+        sufficient_support=False,
+    )
+
+    if not is_post_altair(spec):
+        current_attestations = spec.get_matching_target_attestations(state, epoch)
+        total_active_balance = spec.get_total_active_balance(state)
+        current_target_balance = spec.get_attesting_balance(state, current_attestations)
+        # Check we will not justify the current checkpoint
+        does_justify = current_target_balance * 3 >= total_active_balance * 2
+        assert not does_justify
+        # Ensure we would have justified the current checkpoint w/ the exited validators
+        current_exited_balance = spec.get_total_balance(state, exited_validators)
+        does_justify = (current_target_balance + current_exited_balance) * 3 >= total_active_balance * 2
+        assert does_justify
+    else:
+        current_indices = spec.get_unslashed_participating_indices(state, spec.TIMELY_TARGET_FLAG_INDEX, epoch)
+        total_active_balance = spec.get_total_active_balance(state)
+        current_target_balance = spec.get_total_balance(state, current_indices)
+        # Check we will not justify the current checkpoint
+        does_justify = current_target_balance * 3 >= total_active_balance * 2
+        assert not does_justify
+        # Ensure we would have justified the current checkpoint w/ the exited validators
+        current_exited_balance = spec.get_total_balance(state, exited_validators)
+        does_justify = (current_target_balance + current_exited_balance) * 3 >= total_active_balance * 2
+        assert does_justify
+
+    yield from run_process_just_and_fin(spec, state)
+
+    assert state.current_justified_checkpoint.epoch != epoch

From 30596fb8a1c47b8d14c8619ae3e1c4ccb068b313 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Thu, 2 Sep 2021 15:35:15 -0600
Subject: [PATCH 10/14] Update
 tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py

---
 .../sync_aggregate/test_process_sync_aggregate_random.py        | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py b/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py
index 436e4d04b..d38c3fadf 100644
--- a/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py
+++ b/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py
@@ -28,7 +28,7 @@ from eth2spec.test.context import (
 
 
 def _test_harness_for_randomized_test_case(spec, state, expect_duplicates=False, participation_fn=None):
-    committee_indices = compute_committee_indices(spec, state, state.current_sync_committee)
+    committee_indices = compute_committee_indices(spec, state)
 
     if participation_fn:
         participating_indices = participation_fn(committee_indices)

From 4168943ecf0f3465fdea74f3d9bdc2d21f567153 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Thu, 2 Sep 2021 15:38:52 -0600
Subject: [PATCH 11/14] Update
 tests/core/pyspec/eth2spec/test/helpers/random.py

---
 tests/core/pyspec/eth2spec/test/helpers/random.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/core/pyspec/eth2spec/test/helpers/random.py b/tests/core/pyspec/eth2spec/test/helpers/random.py
index 0bb2a6672..b24d3c8c7 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/random.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/random.py
@@ -141,7 +141,8 @@ def patch_state_to_non_leaking(spec, state):
     performed by other functionality in this module so that if the ``state`` was leaking,
     then the ``state`` is not leaking after.
     """
-    state.justification_bits = (True, True, True, True)
+    state.justification_bits[0] = True
+    state.justification_bits[1] = True
     previous_epoch = spec.get_previous_epoch(state)
     previous_root = spec.get_block_root(state, previous_epoch)
     previous_previous_epoch = max(spec.GENESIS_EPOCH, spec.Epoch(previous_epoch - 1))

From fb4a4f669460fba812715501dfdd0be40fac4f81 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Tue, 7 Sep 2021 13:09:23 -0600
Subject: [PATCH 12/14] Update
 tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py

Co-authored-by: Danny Ryan <dannyjryan@gmail.com>
---
 .../sync_aggregate/test_process_sync_aggregate_random.py        | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py b/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py
index d38c3fadf..903df4081 100644
--- a/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py
+++ b/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate_random.py
@@ -3,7 +3,7 @@ from eth2spec.test.helpers.constants import (
     MAINNET, MINIMAL,
 )
 from eth2spec.test.helpers.random import (
-    randomize_state
+    randomize_state,
 )
 from eth2spec.test.helpers.state import (
     has_active_balance_differential,

From 064b489d18504e796adc4661cd4d641456dfd0a8 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Tue, 7 Sep 2021 12:23:57 -0700
Subject: [PATCH 13/14] Use spec function for total active balance

---
 tests/core/pyspec/eth2spec/test/helpers/state.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tests/core/pyspec/eth2spec/test/helpers/state.py b/tests/core/pyspec/eth2spec/test/helpers/state.py
index 327bebaf8..6f1923e54 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/state.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/state.py
@@ -162,8 +162,6 @@ def has_active_balance_differential(spec, state):
     Ensure there is a difference between the total balance of
     all _active_ validators and _all_ validators.
     """
-    epoch = spec.get_current_epoch(state)
-    active_indices = spec.get_active_validator_indices(state, epoch)
-    active_balance = spec.get_total_balance(state, set(active_indices))
+    active_balance = spec.get_total_active_balance(state)
     total_balance = spec.get_total_balance(state, set(range(len(state.validators))))
     return active_balance // spec.EFFECTIVE_BALANCE_INCREMENT != total_balance // spec.EFFECTIVE_BALANCE_INCREMENT

From 14f71ffb4bb49f436dff5262cebed2720e0bdef7 Mon Sep 17 00:00:00 2001
From: Alex Stokes <r.alex.stokes@gmail.com>
Date: Tue, 7 Sep 2021 12:25:09 -0700
Subject: [PATCH 14/14] Use realistic `withdrawable_epoch` in spec test

---
 .../test_process_justification_and_finalization.py               | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py b/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py
index 1dfc07188..1d3197ba6 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py
@@ -330,6 +330,7 @@ def test_balance_threshold_with_exited_validators(spec, state):
         validator = state.validators[index]
         validator.exit_epoch = epoch
         validator.withdrawable_epoch = epoch + 1
+        validator.withdrawable_epoch = validator.exit_epoch + spec.config.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
 
     exited_validators = get_unslashed_exited_validators(spec, state)
     assert len(exited_validators) != 0