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test: lock in types.Header RLP encoding (#87)
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## Why this should be merged

We're making changes to very sensitive code that, if broken, can result
in block hashes being different.

## How this works

Change-detector test.

## How this was tested

A randomly filled `types.Header` with expected RLP locked as a constant
in the test.
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ARR4N authored Dec 12, 2024
1 parent aa183c5 commit bd44839
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71 changes: 71 additions & 0 deletions core/types/rlp_backwards_compat.libevm_test.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,71 @@
// Copyright 2024 the libevm authors.
//
// The libevm additions to go-ethereum are free software: you can redistribute
// them and/or modify them under the terms of the GNU Lesser General Public License
// as published by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// The libevm additions are distributed in the hope that they will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see
// <http://www.gnu.org/licenses/>.

package types_test

import (
"encoding/hex"
"testing"

"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"

. "github.com/ava-labs/libevm/core/types"
"github.com/ava-labs/libevm/libevm/ethtest"
"github.com/ava-labs/libevm/rlp"
)

func TestHeaderRLPBackwardsCompatibility(t *testing.T) {
// This is a deliberate change-detector test that locks in backwards
// compatibility of RLP encoding.
rng := ethtest.NewPseudoRand(42)

const numExtraBytes = 16
hdr := &Header{
ParentHash: rng.Hash(),
UncleHash: rng.Hash(),
Coinbase: rng.Address(),
Root: rng.Hash(),
TxHash: rng.Hash(),
ReceiptHash: rng.Hash(),
Bloom: rng.Bloom(),
Difficulty: rng.Uint256().ToBig(),
Number: rng.BigUint64(),
GasLimit: rng.Uint64(),
GasUsed: rng.Uint64(),
Time: rng.Uint64(),
Extra: rng.Bytes(numExtraBytes),
MixDigest: rng.Hash(),
Nonce: rng.BlockNonce(),

BaseFee: rng.BigUint64(),
WithdrawalsHash: rng.HashPtr(),
BlobGasUsed: rng.Uint64Ptr(),
ExcessBlobGas: rng.Uint64Ptr(),
ParentBeaconRoot: rng.HashPtr(),
}
t.Logf("%T:\n%+v", hdr, hdr)

// WARNING: changing this hex might break backwards compatibility of RLP
// encoding (i.e. block hashes might change)!
const wantHex = `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`
want, err := hex.DecodeString(wantHex)
require.NoError(t, err, "hex.DecodeString()")

got, err := rlp.EncodeToBytes(hdr)
require.NoErrorf(t, err, "rlp.EncodeToBytes(%T)", hdr)
assert.Equalf(t, want, got, "rlp.EncodeToBytes(%T)", hdr)
}
13 changes: 13 additions & 0 deletions libevm/ethtest/rand.go
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ import (
"golang.org/x/exp/rand"

"github.com/ava-labs/libevm/common"
"github.com/ava-labs/libevm/core/types"
)

// PseudoRand extends [rand.Rand] (*not* crypto/rand).
Expand Down Expand Up @@ -88,3 +89,15 @@ func (r *PseudoRand) Uint64Ptr() *uint64 {
func (r *PseudoRand) Uint256() *uint256.Int {
return new(uint256.Int).SetBytes(r.Bytes(32))
}

// Bloom returns a pseudorandom Bloom.
func (r *PseudoRand) Bloom() (b types.Bloom) {
r.Read(b[:])
return b
}

// BlockNonce returns a pseudorandom BlockNonce.
func (r *PseudoRand) BlockNonce() (n types.BlockNonce) {
r.Read(n[:])
return n
}

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