T8N return an error when asked BLOCKHASH in state test mode

[winsvega]

Original issue:
ethereum/execution-spec-tests#899

here is the evmdump:
http://retesteth.ethdevops.io/temp/pyspecs/frontier__scenarios__test_scenarios__test_blockhash_bug/

error:

.venv/lib/python3.12/site-packages/requests/models.py:974: in json
    return complexjson.loads(self.text, **kwargs)
/usr/lib/python3.12/json/__init__.py:346: in loads
    return _default_decoder.decode(s)
/usr/lib/python3.12/json/decoder.py:337: in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
/usr/lib/python3.12/json/decoder.py:355: in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
E   json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

During handling of the above exception, another exception occurred:
tests/frontier/scenarios/test_scenarios.py:257: in test_scenarios
    state_test(env=tx_env, pre=pre, post=post, tx=tx, post_hint=hint)
src/pytest_plugins/filler/filler.py:836: in __init__
    fixture = self.generate(
src/ethereum_test_specs/state.py:188: in generate
    return self.make_state_test_fixture(t8n, fork, eips, self.post_hint)
src/ethereum_test_specs/state.py:139: in make_state_test_fixture
    transition_tool_output = t8n.evaluate(
src/ethereum_clis/transition_tool.py:487: in evaluate
    return self._evaluate_server(t8n_data=t8n_data, debug_output_path=debug_output_path)
src/ethereum_clis/transition_tool.py:314: in _evaluate_server
    output: TransitionToolOutput = TransitionToolOutput.model_validate(response.json())
.venv/lib/python3.12/site-packages/requests/models.py:978: in json
    raise RequestsJSONDecodeError(e.msg, e.doc, e.pos)
E   requests.exceptions.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
------------------------------------------------------------------------- Captured stderr call --------------------------------------------------------------------------
----------------------------------------
Exception occurred during processing of request from ['local', 0]
Traceback (most recent call last):
  File "/usr/lib/python3.12/socketserver.py", line 318, in _handle_request_noblock
    self.process_request(request, client_address)
  File "/usr/lib/python3.12/socketserver.py", line 349, in process_request
    self.finish_request(request, client_address)
  File "/home/wins/.cache/ethereum-spec-evm-resolver/Cancun/src/ethereum_spec_tools/evm_tools/daemon.py", line 91, in finish_request
    super().finish_request(request, client_address)
  File "/usr/lib/python3.12/socketserver.py", line 362, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/usr/lib/python3.12/socketserver.py", line 761, in __init__
    self.handle()
  File "/usr/lib/python3.12/http/server.py", line 436, in handle
    self.handle_one_request()
  File "/usr/lib/python3.12/http/server.py", line 424, in handle_one_request
    method()
  File "/home/wins/.cache/ethereum-spec-evm-resolver/Cancun/src/ethereum_spec_tools/evm_tools/daemon.py", line 66, in do_POST
    main(args=args, out_file=out_wrapper, in_file=input)
  File "/home/wins/.cache/ethereum-spec-evm-resolver/Cancun/src/ethereum_spec_tools/evm_tools/__init__.py", line 109, in main
    return t8n_tool.run()
           ^^^^^^^^^^^^^^

[SamWilsn]

To confirm, the expected behaviour here is that when the chain does not contain a block at the given number (so for example current block has number 8 but it has no parent), you keccak the string representation of the missing block number?

If my above understanding is correct, we will not implement this behaviour. There are other ways we could provide fake block hashes (like pushing empty blocks before beginning the test), but this is just too weird for us to include in the spec itself.