refactor: convert string-based Enum classes to StrEnum

Replace Enum classes with string values with Python 3.11+ StrEnum for better
type safety, cleaner string conversion, and more explicit string enumeration
semantics in test configuration and execution contexts.

Author: danceratopz

src/ethereum_test_specs/helpers.py

@@ -1,7 +1,7 @@
 """Helper functions."""
 
 from dataclasses import dataclass
-from enum import Enum
+from enum import StrEnum
 from typing import Any, Dict, List
 
 from ethereum_clis import Result
@@ -15,7 +15,7 @@
 from ethereum_test_types import Transaction, TransactionReceipt
 
 
-class ExecutionContext(Enum):
+class ExecutionContext(StrEnum):
     """The execution context in which a test case can fail."""
 
     BLOCK = "Block"

src/ethereum_test_tools/utility/generators.py

@@ -1,7 +1,7 @@
 """Test generator decorators."""
 
 import json
-from enum import Enum
+from enum import StrEnum
 from pathlib import Path
 from typing import Dict, Generator, List, Protocol
 
@@ -17,15 +17,15 @@
 from ethereum_test_vm import Opcodes as Op
 
 
-class DeploymentTestType(Enum):
+class DeploymentTestType(StrEnum):
     """Represents the type of deployment test."""
 
     DEPLOY_BEFORE_FORK = "deploy_before_fork"
     DEPLOY_ON_FORK_BLOCK = "deploy_on_fork_block"
     DEPLOY_AFTER_FORK = "deploy_after_fork"
 
 
-class SystemContractTestType(Enum):
+class SystemContractTestType(StrEnum):
     """Represents the type of system contract test."""
 
     GAS_LIMIT = "system_contract_reaches_gas_limit"
@@ -42,7 +42,7 @@ def param(self):
         )
 
 
-class ContractAddressHasBalance(Enum):
+class ContractAddressHasBalance(StrEnum):
     """Represents whether the target deployment test has a balance before deployment."""
 
     ZERO_BALANCE = "zero_balance"