add test case

Author: qdm12

core/types/block.libevm_test.go

@@ -29,13 +29,16 @@ import (
 	. "github.com/ava-labs/libevm/core/types"
 	"github.com/ava-labs/libevm/crypto"
 	"github.com/ava-labs/libevm/libevm/ethtest"
+	"github.com/ava-labs/libevm/libevm/pseudo"
 	"github.com/ava-labs/libevm/rlp"
 )
 
 type stubHeaderHooks struct {
 	suffix                                   []byte
 	gotRawJSONToUnmarshal, gotRawRLPToDecode []byte
 	setHeaderToOnUnmarshalOrDecode           Header
+	accessor                                 pseudo.Accessor[*Header, *stubHeaderHooks]
+	copied                                   *stubHeaderHooks
 
 	errMarshal, errUnmarshal, errEncode, errDecode error
 }
@@ -75,7 +78,9 @@ func (hh *stubHeaderHooks) DecodeRLP(h *Header, s *rlp.Stream) error {
 	return hh.errDecode
 }
 
-func (hh *stubHeaderHooks) PostCopy(dst *Header) {}
+func (hh *stubHeaderHooks) PostCopy(dst *Header) {
+	hh.accessor.Set(dst, hh.copied)
+}
 
 func TestHeaderHooks(t *testing.T) {
 	TestOnlyClearRegisteredExtras()
@@ -137,6 +142,22 @@ func TestHeaderHooks(t *testing.T) {
 		assert.Equalf(t, &stub.setHeaderToOnUnmarshalOrDecode, hdr, "%T after RLP decoding with hook", hdr)
 	})
 
+	t.Run("PostCopy", func(t *testing.T) {
+		hdr := new(Header)
+		stub := &stubHeaderHooks{
+			accessor: extras.Header,
+			copied: &stubHeaderHooks{
+				suffix: []byte("copied"),
+			},
+		}
+		extras.Header.Set(hdr, stub)
+		cpy := CopyHeader(hdr)
+
+		copiedStub := extras.Header.Get(cpy)
+
+		assert.Equal(t, stub.copied, copiedStub)
+	})
+
 	t.Run("error_propagation", func(t *testing.T) {
 		errMarshal := errors.New("whoops")
 		errUnmarshal := errors.New("is it broken?")