Fix multiprocessing

tests/generators/shuffling/main.py

@@ -1,5 +1,5 @@
-from eth_utils import to_tuple
 from typing import Iterable
+import random
 
 from eth2spec.gen_helpers.gen_base import gen_runner, gen_typing
 from eth2spec.test.helpers.typing import PresetBaseName
@@ -8,6 +8,14 @@
 from eth2spec.test.helpers.constants import PHASE0, MINIMAL, MAINNET
 
 
+def generate_random_bytes(rng=random.Random(5566)):
+    random_bytes = bytes(rng.randint(0, 255) for _ in range(32))
+    return random_bytes
+
+# NOTE: somehow the random.Random generated seeds do not have pickle issue.
+rng = random.Random(1234)
+seeds = [generate_random_bytes(rng) for i in range(30)]
+
 def shuffling_case_fn(spec, seed, count):
     yield 'mapping', 'data', {
         'seed': '0x' + seed.hex(),
@@ -20,9 +28,8 @@ def shuffling_case(spec, seed, count):
     return f'shuffle_0x{seed.hex()}_{count}', lambda: shuffling_case_fn(spec, seed, count)
 
 
-@to_tuple
 def shuffling_test_cases(spec):
-    for seed in [spec.hash(seed_init_value.to_bytes(length=4, byteorder='little')) for seed_init_value in range(30)]:
+    for seed in seeds:
         for count in [0, 1, 2, 3, 5, 10, 33, 100, 1000, 9999]:
             yield shuffling_case(spec, seed, count)
 
@@ -47,11 +54,13 @@ def cases_fn() -> Iterable[gen_typing.TestCase]:
                 handler_name='core',
                 suite_name='shuffle',
                 case_name=case_name,
-                case_fn=case_fn
+                case_fn=case_fn,
             )
 
     return gen_typing.TestProvider(prepare=prepare_fn, make_cases=cases_fn)
 
 
 if __name__ == "__main__":
-    gen_runner.run_generator("shuffling", [create_provider(MINIMAL), create_provider(MAINNET)])
+    gen_runner.run_generator("shuffling", [
+        create_provider(MINIMAL), create_provider(MAINNET)]
+    )