chore(core/types): add Test_CopyHeader test

core/types/block_test.go

@@ -22,6 +22,8 @@ import (
 	"math/big"
 	"reflect"
 	"testing"
+	"unicode"
+	"unsafe"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/math"
@@ -29,6 +31,8 @@ import (
 	"github.com/ethereum/go-ethereum/internal/blocktest"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 // from bcValidBlockTest.json, "SimpleTx"
@@ -318,3 +322,140 @@ func TestRlpDecodeParentHash(t *testing.T) {
 		}
 	}
 }
+
+func TestCopyHeader(t *testing.T) {
+	t.Parallel()
+
+	t.Run("empty_header", func(t *testing.T) {
+		t.Parallel()
+
+		empty := Header{}
+		cpy := CopyHeader(&empty)
+
+		want := &Header{
+			Difficulty: new(big.Int),
+			Number:     new(big.Int),
+		}
+		assert.Equal(t, want, cpy)
+	})
+
+	t.Run("filled_header", func(t *testing.T) {
+		t.Parallel()
+
+		h := Header{
+			ParentHash:       common.Hash{1},
+			UncleHash:        common.Hash{2},
+			Coinbase:         common.Address{3},
+			Root:             common.Hash{4},
+			TxHash:           common.Hash{5},
+			ReceiptHash:      common.Hash{6},
+			Bloom:            Bloom{7},
+			Difficulty:       big.NewInt(8),
+			Number:           big.NewInt(9),
+			GasLimit:         10,
+			GasUsed:          11,
+			Time:             12,
+			Extra:            []byte{13},
+			MixDigest:        common.Hash{14},
+			Nonce:            BlockNonce{15},
+			BaseFee:          big.NewInt(16),
+			WithdrawalsHash:  &common.Hash{17},
+			BlobGasUsed:      ptrTo(uint64(18)),
+			ExcessBlobGas:    ptrTo(uint64(19)),
+			ParentBeaconRoot: &common.Hash{20},
+			RequestsHash:     &common.Hash{21},
+		}
+
+		allFieldsAreSet(t, h)
+
+		cpy := CopyHeader(&h)
+
+		want := &Header{
+			ParentHash:       common.Hash{1},
+			UncleHash:        common.Hash{2},
+			Coinbase:         common.Address{3},
+			Root:             common.Hash{4},
+			TxHash:           common.Hash{5},
+			ReceiptHash:      common.Hash{6},
+			Bloom:            Bloom{7},
+			Difficulty:       big.NewInt(8),
+			Number:           big.NewInt(9),
+			GasLimit:         10,
+			GasUsed:          11,
+			Time:             12,
+			Extra:            []byte{13},
+			MixDigest:        common.Hash{14},
+			Nonce:            BlockNonce{15},
+			BaseFee:          big.NewInt(16),
+			WithdrawalsHash:  &common.Hash{17},
+			BlobGasUsed:      ptrTo(uint64(18)),
+			ExcessBlobGas:    ptrTo(uint64(19)),
+			ParentBeaconRoot: &common.Hash{20},
+			RequestsHash:     &common.Hash{21},
+		}
+		assert.Equal(t, want, cpy)
+
+		// Mutate each non-value field to ensure they are not shared
+		v := reflect.ValueOf(&h).Elem()
+		for i := 0; i < v.NumField(); i++ {
+			field := v.Field(i)
+			fieldName := v.Type().Field(i).Name
+			if unicode.IsLower(rune(fieldName[0])) {
+				field = reflect.NewAt(field.Type(), unsafe.Pointer(field.UnsafeAddr())).Elem()
+			}
+			var originalField any
+			switch field.Kind() {
+			case reflect.Array, reflect.Uint64: // values
+			case reflect.Slice:
+				originalField = field.Interface()
+				switch originalField.(type) {
+				case []byte:
+					field.Set(reflect.Append(field, reflect.ValueOf(byte(1))))
+				default:
+					t.Fatalf("unexpected slice type %T for %q", originalField, fieldName)
+				}
+				originalField = field.Interface()
+			case reflect.Pointer:
+				originalField = field.Interface()
+				switch ptr := originalField.(type) {
+				case *big.Int:
+					ptr.Add(ptr, big.NewInt(1))
+				case *uint64:
+					*ptr++
+				case *common.Hash:
+					ptr[0]++
+				default:
+					t.Fatalf("unexpected pointer type %T for %q", ptr, fieldName)
+				}
+			default:
+				t.Fatalf("unexpected field kind %v for %q", field.Kind(), fieldName)
+			}
+			cpyField := reflect.ValueOf(*cpy).Field(i).Interface()
+			assert.NotEqualf(t, originalField, cpyField, "field %q", fieldName)
+		}
+	})
+}
+
+func ptrTo[T any](x T) *T { return &x }
+
+func allFieldsAreSet(t *testing.T, x any) {
+	v := reflect.ValueOf(x)
+	typ := v.Type()
+	require.Equal(t, reflect.Struct, typ.Kind())
+	for i := 0; i < v.NumField(); i++ {
+		field := v.Field(i)
+		fieldName := typ.Field(i).Name
+		fieldValue := field
+		if unicode.IsLower(rune(fieldName[0])) { // unexported
+			require.Falsef(t, field.IsNil(), "field %q is nil", fieldName)
+			field = reflect.NewAt(field.Type(), unsafe.Pointer(field.UnsafeAddr())).Elem()
+			fieldValue = field
+		}
+		if field.Kind() == reflect.Pointer {
+			require.NotNilf(t, field.Interface(), "field %q is nil", fieldName)
+			fieldValue = field.Elem()
+		}
+		isSet := fieldValue.IsValid() && !fieldValue.IsZero()
+		require.True(t, isSet, "field %q is not set", fieldName)
+	}
+}