feat(tests): EIP-7918 - Blob base fee bounded by execution cost (#1685)

* feat(forks|tests): eip-7918 initial tests plus eip-4844 adjustments.

* chore(tests): extra param and docstring tweak.

Author: spencer-tb

docs/CHANGELOG.md

@@ -74,6 +74,7 @@ Users can select any of the artifacts depending on their testing needs for their
 - ✨ Introduce blockchain tests for ZKEVM to cover the scenario of pure ether transfers [#1742](https://github.com/ethereum/execution-spec-tests/pull/1742).
 - ✨ [EIP-7934](https://eips.ethereum.org/EIPS/eip-7934): Add test cases for the block RLP max limit of 10MiB ([#1730](https://github.com/ethereum/execution-spec-tests/pull/1730)).
 - ✨ [EIP-7939](https://eips.ethereum.org/EIPS/eip-7939) Add count leading zeros (CLZ) opcode tests for Osaka ([#1733](https://github.com/ethereum/execution-spec-tests/pull/1733)).
+- ✨ [EIP-7918](https://eips.ethereum.org/EIPS/eip-7918): Blob base fee bounded by execution cost test cases (initial), includes some adjustments to [EIP-4844](https://eips.ethereum.org/EIPS/eip-4844) tests ([#1685](https://github.com/ethereum/execution-spec-tests/pull/1685)).
 
 ## [v4.5.0](https://github.com/ethereum/execution-spec-tests/releases/tag/v4.5.0) - 2025-05-14
 

src/ethereum_test_forks/base_fork.py

@@ -96,6 +96,7 @@ def __call__(
         parent_excess_blobs: int | None = None,
         parent_blob_gas_used: int | None = None,
         parent_blob_count: int | None = None,
+        parent_base_fee_per_gas: int,
     ) -> int:
         """Return the excess blob gas given the parent's excess blob gas and blob gas used."""
         pass

src/ethereum_test_forks/forks/forks.py

@@ -960,6 +960,7 @@ def fn(
             parent_excess_blobs: int | None = None,
             parent_blob_gas_used: int | None = None,
             parent_blob_count: int | None = None,
+            parent_base_fee_per_gas: int,  # Required for Osaka as using this as base
         ) -> int:
             if parent_excess_blob_gas is None:
                 assert parent_excess_blobs is not None, "Parent excess blobs are required"
@@ -1388,6 +1389,55 @@ def precompiles(cls, block_number: int = 0, timestamp: int = 0) -> List[Address]
         """
         return [Address(0x100)] + super(Osaka, cls).precompiles(block_number, timestamp)
 
+    @classmethod
+    def excess_blob_gas_calculator(
+        cls, block_number: int = 0, timestamp: int = 0
+    ) -> ExcessBlobGasCalculator:
+        """Return a callable that calculates the excess blob gas for a block."""
+        target_blobs_per_block = cls.target_blobs_per_block(block_number, timestamp)
+        blob_gas_per_blob = cls.blob_gas_per_blob(block_number, timestamp)
+        target_blob_gas_per_block = target_blobs_per_block * blob_gas_per_blob
+        max_blobs_per_block = cls.max_blobs_per_block(block_number, timestamp)
+        blob_base_cost = 2**14  # EIP-7918 new parameter
+
+        def fn(
+            *,
+            parent_excess_blob_gas: int | None = None,
+            parent_excess_blobs: int | None = None,
+            parent_blob_gas_used: int | None = None,
+            parent_blob_count: int | None = None,
+            parent_base_fee_per_gas: int,  # EIP-7918 additional parameter
+        ) -> int:
+            if parent_excess_blob_gas is None:
+                assert parent_excess_blobs is not None, "Parent excess blobs are required"
+                parent_excess_blob_gas = parent_excess_blobs * blob_gas_per_blob
+            if parent_blob_gas_used is None:
+                assert parent_blob_count is not None, "Parent blob count is required"
+                parent_blob_gas_used = parent_blob_count * blob_gas_per_blob
+            if parent_excess_blob_gas + parent_blob_gas_used < target_blob_gas_per_block:
+                return 0
+
+            # EIP-7918: Apply reserve price when execution costs dominate blob costs
+            current_blob_base_fee = cls.blob_gas_price_calculator()(
+                excess_blob_gas=parent_excess_blob_gas
+            )
+            reserve_price_active = (
+                blob_base_cost * parent_base_fee_per_gas
+                > blob_gas_per_blob * current_blob_base_fee
+            )
+            if reserve_price_active:
+                blob_excess_adjustment = (
+                    parent_blob_gas_used
+                    * (max_blobs_per_block - target_blobs_per_block)
+                    // max_blobs_per_block
+                )
+                return parent_excess_blob_gas + blob_excess_adjustment
+
+            # Original EIP-4844 calculation
+            return parent_excess_blob_gas + parent_blob_gas_used - target_blob_gas_per_block
+
+        return fn
+
 
 class EOFv1(Prague, solc_name="cancun"):
     """EOF fork."""

tests/cancun/eip4844_blobs/conftest.py

@@ -70,6 +70,7 @@ def excess_blob_gas(
     fork: Fork,
     parent_excess_blobs: int | None,
     parent_blobs: int | None,
+    block_base_fee_per_gas: int,
 ) -> int | None:
     """
     Calculate the excess blob gas of the block under test from the parent block.
@@ -78,10 +79,10 @@ def excess_blob_gas(
     """
     if parent_excess_blobs is None or parent_blobs is None:
         return None
-    excess_blob_gas = fork.excess_blob_gas_calculator()
-    return excess_blob_gas(
+    return fork.excess_blob_gas_calculator()(
         parent_excess_blobs=parent_excess_blobs,
         parent_blob_count=parent_blobs,
+        parent_base_fee_per_gas=block_base_fee_per_gas,
     )
 
 
@@ -90,6 +91,7 @@ def correct_excess_blob_gas(
     fork: Fork,
     parent_excess_blobs: int | None,
     parent_blobs: int | None,
+    block_base_fee_per_gas: int,
 ) -> int:
     """
     Calculate the correct excess blob gas of the block under test from the parent block.
@@ -98,18 +100,19 @@ def correct_excess_blob_gas(
     """
     if parent_excess_blobs is None or parent_blobs is None:
         return 0
-    excess_blob_gas = fork.excess_blob_gas_calculator()
-    return excess_blob_gas(
+    return fork.excess_blob_gas_calculator()(
         parent_excess_blobs=parent_excess_blobs,
         parent_blob_count=parent_blobs,
+        parent_base_fee_per_gas=block_base_fee_per_gas,
     )
 
 
 @pytest.fixture
-def block_fee_per_blob_gas(  # noqa: D103
+def block_fee_per_blob_gas(
     fork: Fork,
     correct_excess_blob_gas: int,
 ) -> int:
+    """Calculate the blob gas price for the current block."""
     get_blob_gas_price = fork.blob_gas_price_calculator()
     return get_blob_gas_price(excess_blob_gas=correct_excess_blob_gas)
 
@@ -251,7 +254,7 @@ def non_zero_blob_gas_used_genesis_block(
     genesis_excess_blob_gas: int,
     parent_excess_blob_gas: int,
     tx_max_fee_per_gas: int,
-    target_blobs_per_block: int,
+    block_base_fee_per_gas: int,
 ) -> Block | None:
     """
     For test cases with a non-zero blobGasUsed field in the
@@ -271,10 +274,17 @@ def non_zero_blob_gas_used_genesis_block(
         return None
 
     excess_blob_gas_calculator = fork.excess_blob_gas_calculator(block_number=1)
-    assert parent_excess_blob_gas == excess_blob_gas_calculator(
+    calculated_excess_blob_gas = excess_blob_gas_calculator(
         parent_excess_blob_gas=genesis_excess_blob_gas,
         parent_blob_count=0,
-    ), "parent excess blob gas is not as expected for extra block"
+        parent_base_fee_per_gas=block_base_fee_per_gas,
+    )
+
+    assert parent_excess_blob_gas == calculated_excess_blob_gas, (
+        f"parent excess blob gas mismatch: expected {parent_excess_blob_gas}, "
+        f"got {calculated_excess_blob_gas} for {parent_blobs} blobs "
+        f"with base_fee_per_gas {block_base_fee_per_gas}"
+    )
 
     sender = pre.fund_eoa(10**27)
 

tests/cancun/eip4844_blobs/spec.py

@@ -45,6 +45,7 @@ class Spec:
     # LIMIT_BLOBS_PER_TX = 2**12
     HASH_OPCODE_BYTE = 0x49
     HASH_GAS_COST = 3
+    GAS_PER_BLOB = 2**17
 
     @classmethod
     def kzg_to_versioned_hash(

tests/cancun/eip4844_blobs/test_blob_txs.py

@@ -312,6 +312,7 @@ def expected_excess_blob_gas(
     parent_blobs: Optional[int],
     block_number: int,
     block_timestamp: int,
+    block_base_fee_per_gas: int,
 ) -> Optional[int | Removable]:
     """Calculate blob gas used by the test block."""
     if not fork.header_excess_blob_gas_required(
@@ -322,6 +323,7 @@ def expected_excess_blob_gas(
     return excess_blob_gas(
         parent_excess_blobs=parent_excess_blobs if parent_excess_blobs else 0,
         parent_blob_count=parent_blobs if parent_blobs else 0,
+        parent_base_fee_per_gas=block_base_fee_per_gas,
     )
 
 
@@ -374,6 +376,7 @@ def block(
     "blobs_per_tx",
     SpecHelpers.all_valid_blob_combinations,
 )
+@pytest.mark.parametrize("block_base_fee_per_gas", [7, 100])
 @pytest.mark.valid_from("Cancun")
 def test_valid_blob_tx_combinations(
     blockchain_test: BlockchainTestFiller,
@@ -664,6 +667,7 @@ def test_insufficient_balance_blob_tx(
     [b"", b"\x00", b"\x01"],
     ids=["no_calldata", "single_zero_calldata", "single_one_calldata"],
 )
+@pytest.mark.parametrize("block_base_fee_per_gas", [7, 100])
 @pytest.mark.parametrize("tx_max_fee_per_blob_gas_multiplier", [1, 100, 10000])
 @pytest.mark.valid_from("Cancun")
 def test_sufficient_balance_blob_tx(

tests/cancun/eip4844_blobs/test_excess_blob_gas_fork_transition.py

@@ -131,6 +131,7 @@ def fork_block_excess_blob_gas(
     fork: Fork,
     pre_fork_excess_blobs: int,
     pre_fork_blobs_per_block: int,
+    block_base_fee_per_gas: int,
 ) -> int:
     """Calculate the expected excess blob gas for the fork block."""
     if pre_fork_blobs_per_block == 0:
@@ -139,6 +140,7 @@ def fork_block_excess_blob_gas(
     return calc_excess_blob_gas_post_fork(
         parent_excess_blobs=pre_fork_excess_blobs,
         parent_blob_count=pre_fork_blobs_per_block,
+        parent_base_fee_per_gas=block_base_fee_per_gas,
     )
 
 
@@ -382,6 +384,7 @@ def test_fork_transition_excess_blob_gas_at_blob_genesis(
         ),
     ],
 )
+@pytest.mark.parametrize("block_base_fee_per_gas", [7, 16, 23])
 def test_fork_transition_excess_blob_gas_post_blob_genesis(
     blockchain_test: BlockchainTestFiller,
     env: Environment,

tests/osaka/eip7594_peerdas/test_get_blobs.py

@@ -51,6 +51,12 @@ def tx_gas() -> int:
     return 21_000
 
 
+@pytest.fixture
+def block_base_fee_per_gas() -> int:
+    """Return default max fee per gas for transactions sent during test."""
+    return 7
+
+
 @pytest.fixture
 def tx_calldata() -> bytes:
     """Calldata in transactions sent during test."""
@@ -83,6 +89,7 @@ def excess_blob_gas(
     fork: Fork,
     parent_excess_blobs: int | None,
     parent_blobs: int | None,
+    block_base_fee_per_gas: int,
 ) -> int | None:
     """
     Calculate the excess blob gas of the block under test from the parent block.
@@ -95,6 +102,7 @@ def excess_blob_gas(
     return excess_blob_gas(
         parent_excess_blobs=parent_excess_blobs,
         parent_blob_count=parent_blobs,
+        parent_base_fee_per_gas=block_base_fee_per_gas,
     )
 
 

tests/osaka/eip7918_blob_reserve_price/__init__.py

@@ -0,0 +1 @@
+"""Cross-client EIP-7918 Tests."""