EVM opcode refactor test

opcode_add.nim

import
  stint,
  ../nimbus/constants,
  ../nimbus/vm/interpreter/[opcodes_impl, vm_forks],
  ../nimbus/vm/[message, computation, stack],
  ../nimbus/utils/header,
  ../nimbus/db/[db_chain, state_db, backends/memory_backend]

let msg = newMessage(
    to=ZERO_ADDRESS, #fixture{"exec"}{"address"}.getStr,
    sender=ZERO_ADDRESS, #fixture{"exec"}{"caller"}.getStr,
    value=0.u256,
    data = @[],
    code="0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff01",
    gas=100_000,
    gasPrice=1)

let h = BlockHeader(blockNumber: 100.u256)
var vm = newNimbusVM(h, newBaseChainDB(newMemoryDB()))
var c = newBaseComputation(vm.state, msg)

echo c.stack.values

c.stack = newStack()
c.stack.push 10.u256
c.stack.push 20.u256

echo "\n"
echo c.stack.values

addFkFrontier(c)
echo "\n"
echo c.stack.values