refactor(core/types): Body backwards-compatibility out of package types_test (#131)

## Why this should be merged

Simplify testing in #130.

## How this works

Backwards-compatibility tests were originally created in `package
types_test` because the first one uses `ethtest` and would have caused a
circular dependency. None of the later tests have this issue so they
were moved into `package types`. The `cmpeth` test utility isn't
currently needed anywhere else so its functionality is collapsed inside
this new file.

## How this was tested

N/A as simply moving existing tests to different files.

core/types/backwards_compat.libevm_test.go

@@ -14,7 +14,7 @@
 // along with the go-ethereum library. If not, see
 // <http://www.gnu.org/licenses/>.
 
-package types_test
+package types
 
 import (
 	"encoding/hex"
@@ -26,91 +26,9 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/ava-labs/libevm/common"
-	. "github.com/ava-labs/libevm/core/types"
-	"github.com/ava-labs/libevm/libevm/cmpeth"
-	"github.com/ava-labs/libevm/libevm/ethtest"
 	"github.com/ava-labs/libevm/rlp"
 )
 
-func TestHeaderRLPBackwardsCompatibility(t *testing.T) {
-	tests := []struct {
-		name     string
-		register func()
-	}{
-		{
-			name:     "no registered extras",
-			register: func() {},
-		},
-		{
-			name: "no-op header hooks",
-			register: func() {
-				RegisterExtras[NOOPHeaderHooks, *NOOPHeaderHooks, struct{}]()
-			},
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			TestOnlyClearRegisteredExtras()
-			defer TestOnlyClearRegisteredExtras()
-			tt.register()
-			testHeaderRLPBackwardsCompatibility(t)
-		})
-	}
-}
-
-//nolint:thelper
-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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`
-	wantRLP, err := hex.DecodeString(wantHex)
-	require.NoError(t, err, "hex.DecodeString()")
-
-	t.Run("Encode", func(t *testing.T) {
-		got, err := rlp.EncodeToBytes(hdr)
-		require.NoErrorf(t, err, "rlp.EncodeToBytes(%T)", hdr)
-		assert.Equalf(t, wantRLP, got, "rlp.EncodeToBytes(%T)", hdr)
-	})
-
-	t.Run("Decode", func(t *testing.T) {
-		got := new(Header)
-		err := rlp.DecodeBytes(wantRLP, got)
-		require.NoErrorf(t, err, "rlp.DecodeBytes(..., %T)", hdr)
-		assert.Equal(t, hdr, got)
-	})
-}
-
 func TestBodyRLPBackwardsCompatibility(t *testing.T) {
 	newTx := func(nonce uint64) *Transaction { return NewTx(&LegacyTx{Nonce: nonce}) }
 	newHdr := func(hashLow byte) *Header { return &Header{ParentHash: common.Hash{hashLow}} }
@@ -176,8 +94,8 @@ func TestBodyRLPBackwardsCompatibility(t *testing.T) {
 				}
 
 				opts := cmp.Options{
-					cmpeth.CompareHeadersByHash(),
+					cmp.Comparer((*Header).equalHash),
-					cmpeth.CompareTransactionsByBinary(t),
+					cmp.Comparer((*Transaction).equalHash),
 				}
 				if diff := cmp.Diff(body, got, opts); diff != "" {
 					t.Errorf("rlp.DecodeBytes(rlp.EncodeToBytes(%#v)) diff (-want +got):\n%s", body, diff)
@@ -292,8 +210,8 @@ func TestBodyRLPCChainCompat(t *testing.T) {
 				assert.Equal(t, tt.extra, &extra, "rlp.DecodeBytes(%#x, [%T as registered extra in %T carrier])", wantRLP, &extra, got)
 
 				opts := cmp.Options{
-					cmpeth.CompareHeadersByHash(),
+					cmp.Comparer((*Header).equalHash),
-					cmpeth.CompareTransactionsByBinary(t),
+					cmp.Comparer((*Transaction).equalHash),
 				}
 				if diff := cmp.Diff(body, got, opts); diff != "" {
 					t.Errorf("rlp.DecodeBytes(%#x, [%T while carrying registered %T extra payload]) diff (-want +got):\n%s", wantRLP, got, &extra, diff)
@@ -302,3 +220,24 @@ func TestBodyRLPCChainCompat(t *testing.T) {
 		})
 	}
 }
+
+// equalHash reports whether `a` and `b` have equal hashes. It allows for nil
+// arguments, returning `true` if both are nil, `false` if only one is nil,
+// otherwise `a.Hash() == b.Hash()`.
+func equalHash[
+	T any, P interface {
+		Hash() common.Hash
+		*T
+	},
+](a, b P) bool {
+	if a == nil && b == nil {
+		return true
+	}
+	if a == nil || b == nil {
+		return false
+	}
+	return a.Hash() == b.Hash()
+}
+
+func (h *Header) equalHash(hh *Header) bool           { return equalHash(h, hh) }
+func (tx *Transaction) equalHash(u *Transaction) bool { return equalHash(tx, u) }

core/types/backwards_compat_diffpkg.libevm_test.go

@@ -0,0 +1,108 @@
+// Copyright 2024-2025 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) {
+	tests := []struct {
+		name     string
+		register func()
+	}{
+		{
+			name:     "no registered extras",
+			register: func() {},
+		},
+		{
+			name: "no-op header hooks",
+			register: func() {
+				RegisterExtras[NOOPHeaderHooks, *NOOPHeaderHooks, struct{}]()
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			TestOnlyClearRegisteredExtras()
+			defer TestOnlyClearRegisteredExtras()
+			tt.register()
+			testHeaderRLPBackwardsCompatibility(t)
+		})
+	}
+}
+
+//nolint:thelper
+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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`
+	wantRLP, err := hex.DecodeString(wantHex)
+	require.NoError(t, err, "hex.DecodeString()")
+
+	t.Run("Encode", func(t *testing.T) {
+		got, err := rlp.EncodeToBytes(hdr)
+		require.NoErrorf(t, err, "rlp.EncodeToBytes(%T)", hdr)
+		assert.Equalf(t, wantRLP, got, "rlp.EncodeToBytes(%T)", hdr)
+	})
+
+	t.Run("Decode", func(t *testing.T) {
+		got := new(Header)
+		err := rlp.DecodeBytes(wantRLP, got)
+		require.NoErrorf(t, err, "rlp.DecodeBytes(..., %T)", hdr)
+		assert.Equal(t, hdr, got)
+	})
+}

libevm/cmpeth/cmpeth.go

@@ -1,66 +0,0 @@
-// Copyright 2025 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 cmpeth provides ETH-specific options for the cmp package.
-package cmpeth
-
-import (
-	"bytes"
-	"testing"
-
-	"github.com/google/go-cmp/cmp"
-
-	"github.com/ava-labs/libevm/core/types"
-)
-
-// CompareHeadersByHash returns an option to compare Headers based on
-// [types.Header.Hash] equality.
-func CompareHeadersByHash() cmp.Option {
-	return cmp.Comparer(func(a, b *types.Header) bool {
-		return a.Hash() == b.Hash()
-	})
-}
-
-// CompareTransactionsByBinary returns an option to compare Transactions based
-// on [types.Transaction.MarshalBinary] equality. Two nil pointers are
-// considered equal.
-//
-// If MarshalBinary() returns an error, it will be reported with
-// [testing.TB.Fatal].
-func CompareTransactionsByBinary(tb testing.TB) cmp.Option {
-	tb.Helper()
-	return cmp.Comparer(func(a, b *types.Transaction) bool {
-		tb.Helper()
-
-		if a == nil && b == nil {
-			return true
-		}
-		if a == nil || b == nil {
-			return false
-		}
-
-		return bytes.Equal(marshalTxBinary(tb, a), marshalTxBinary(tb, b))
-	})
-}
-
-func marshalTxBinary(tb testing.TB, tx *types.Transaction) []byte {
-	tb.Helper()
-	buf, err := tx.MarshalBinary()
-	if err != nil {
-		tb.Fatalf("%T.MarshalBinary() error %v", tx, err)
-	}
-	return buf
-}