Add identity returndata tests and additional blake2 test cases

Author: reedsa

tests/frontier/precompiles/test_identity_returndata_size.py

@@ -0,0 +1,68 @@
+"""abstract: Test identity precompile output size."""
+
+import pytest
+
+from ethereum_test_forks import Fork
+from ethereum_test_tools import (
+    Account,
+    Alloc,
+    Environment,
+    StateTestFiller,
+    Transaction,
+)
+from ethereum_test_tools import Opcodes as Op
+
+REFERENCE_SPEC_GIT_PATH = "EIPS/eip-152.md"
+REFERENCE_SPEC_VERSION = "5510973b40973b6aa774f04c9caba823c8ff8460"
+
+IDENTITY_PRECOMPILE_ADDRESS = 0x04
+
+
+@pytest.mark.valid_from("Byzantium")
+@pytest.mark.parametrize(
+    ["args_size", "output_size", "returndatasize"],
+    [
+        pytest.param(16, 32, 16, id="output_16"),
+        pytest.param(32, 16, 32, id="output_32"),
+    ],
+)
+def test_identity_precompile_returndata(
+    state_test: StateTestFiller,
+    pre: Alloc,
+    fork: Fork,
+    args_size: int,
+    output_size: int,
+    returndatasize: int,
+):
+    """Test identity precompile RETURNDATA is sized correctly based on the input size."""
+    env = Environment()
+
+    account = pre.deploy_contract(
+        Op.MSTORE(0, 0)
+        + Op.GAS
+        + Op.MSTORE(0, 0x112233445566778899AABBCCDDEEFF00112233445566778899AABBCCDDEEFF00)
+        + Op.CALL(
+            address=IDENTITY_PRECOMPILE_ADDRESS,
+            args_offset=0,
+            args_size=args_size,
+            output_offset=0x10,
+            output_size=output_size,
+        )
+        + Op.POP
+        + Op.SSTORE(0, Op.RETURNDATASIZE)
+        + Op.STOP,
+        storage={0: 0xDEADBEEF},
+    )
+
+    tx = Transaction(
+        to=account,
+        sender=pre.fund_eoa(),
+        gas_limit=1_000_000,
+        protected=True,
+    )
+
+    # Delegatecall to the precompile will fail and consume the specified gas amount
+    # Otherwise delegatecall will succeed and no gas will be consumed
+    post = {account: Account(storage={0: returndatasize})}
+
+    state_test(env=env, pre=pre, post=post, tx=tx)