test: HeaderHooks JSON round-tripping

Author: ARR4N

core/types/block.libevm_test.go

@@ -17,7 +17,9 @@
 package types_test
 
 import (
+	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"testing"
 
@@ -31,27 +33,33 @@ import (
 )
 
 type stubHeaderHooks struct {
-	rlpSuffix           []byte
-	gotRawRLPToDecode   []byte
-	setHeaderToOnDecode Header
+	suffix                                   []byte
+	gotRawJSONToUnmarshal, gotRawRLPToDecode []byte
+	setHeaderToOnUnmarshalOrDecode           Header
 
-	errEncode, errDecode error
+	errMarshal, errUnmarshal, errEncode, errDecode error
+}
+
+func fakeHeaderJSON(h *Header, suffix []byte) []byte {
+	return []byte(fmt.Sprintf(`"%#x:%#x"`, h.ParentHash, suffix))
 }
 
 func fakeHeaderRLP(h *Header, suffix []byte) []byte {
 	return append(crypto.Keccak256(h.ParentHash[:]), suffix...)
 }
 
 func (hh *stubHeaderHooks) MarshalJSON(h *Header) ([]byte, error) { //nolint:govet
-	return nil, errors.New("TODO")
+	return fakeHeaderJSON(h, hh.suffix), hh.errMarshal
 }
 
 func (hh *stubHeaderHooks) UnmarshalJSON(h *Header, b []byte) error { //nolint:govet
-	return errors.New("TODO")
+	hh.gotRawJSONToUnmarshal = b
+	*h = hh.setHeaderToOnUnmarshalOrDecode
+	return hh.errUnmarshal
 }
 
 func (hh *stubHeaderHooks) EncodeRLP(h *Header, w io.Writer) error {
-	if _, err := w.Write(fakeHeaderRLP(h, hh.rlpSuffix)); err != nil {
+	if _, err := w.Write(fakeHeaderRLP(h, hh.suffix)); err != nil {
 		return err
 	}
 	return hh.errEncode
@@ -63,7 +71,7 @@ func (hh *stubHeaderHooks) DecodeRLP(h *Header, s *rlp.Stream) error {
 		return err
 	}
 	hh.gotRawRLPToDecode = r
-	*h = hh.setHeaderToOnDecode
+	*h = hh.setHeaderToOnUnmarshalOrDecode
 	return hh.errDecode
 }
 
@@ -74,14 +82,36 @@ func TestHeaderHooks(t *testing.T) {
 	extras := RegisterExtras[stubHeaderHooks, *stubHeaderHooks, struct{}]()
 	rng := ethtest.NewPseudoRand(13579)
 
-	t.Run("EncodeRLP", func(t *testing.T) {
-		suffix := rng.Bytes(8)
+	suffix := rng.Bytes(8)
+	hdr := &Header{
+		ParentHash: rng.Hash(),
+	}
+	extras.Header.Get(hdr).suffix = append([]byte{}, suffix...)
 
-		hdr := &Header{
-			ParentHash: rng.Hash(),
+	t.Run("MarshalJSON", func(t *testing.T) {
+		got, err := json.Marshal(hdr)
+		require.NoError(t, err, "json.Marshal(%T)", hdr)
+		assert.Equal(t, fakeHeaderJSON(hdr, suffix), got)
+	})
+
+	t.Run("UnmarshalJSON", func(t *testing.T) {
+		hdr := new(Header)
+		stub := &stubHeaderHooks{
+			setHeaderToOnUnmarshalOrDecode: Header{
+				Extra: []byte("can you solve this puzzle? 0xbda01b6cf56c303bd3f581599c0d5c0b"),
+			},
 		}
-		extras.Header.Get(hdr).rlpSuffix = append([]byte{}, suffix...)
+		extras.Header.Set(hdr, stub)
+
+		input := fmt.Sprintf("%q", "hello, JSON world")
+		err := json.Unmarshal([]byte(input), hdr)
+		require.NoErrorf(t, err, "json.Unmarshal()")
+
+		assert.Equal(t, input, string(stub.gotRawJSONToUnmarshal), "raw JSON received by hook")
+		assert.Equal(t, &stub.setHeaderToOnUnmarshalOrDecode, hdr, "%T after JSON unmarshalling with hook", hdr)
+	})
 
+	t.Run("EncodeRLP", func(t *testing.T) {
 		got, err := rlp.EncodeToBytes(hdr)
 		require.NoError(t, err, "rlp.EncodeToBytes(%T)", hdr)
 		assert.Equal(t, fakeHeaderRLP(hdr, suffix), got)
@@ -93,7 +123,7 @@ func TestHeaderHooks(t *testing.T) {
 
 		hdr := new(Header)
 		stub := &stubHeaderHooks{
-			setHeaderToOnDecode: Header{
+			setHeaderToOnUnmarshalOrDecode: Header{
 				Extra: []byte("arr4n was here"),
 			},
 		}
@@ -102,19 +132,31 @@ func TestHeaderHooks(t *testing.T) {
 		require.NoErrorf(t, err, "rlp.DecodeBytes(%#x)", input)
 
 		assert.Equal(t, input, stub.gotRawRLPToDecode, "raw RLP received by hooks")
-		assert.Equalf(t, &stub.setHeaderToOnDecode, hdr, "%T after RLP decoding with hook", hdr)
+		assert.Equalf(t, &stub.setHeaderToOnUnmarshalOrDecode, hdr, "%T after RLP decoding with hook", hdr)
 	})
 
 	t.Run("error_propagation", func(t *testing.T) {
+		errMarshal := errors.New("whoops")
+		errUnmarshal := errors.New("is it broken?")
 		errEncode := errors.New("uh oh")
 		errDecode := errors.New("something bad happened")
 
 		hdr := new(Header)
-		extras.Header.Set(hdr, &stubHeaderHooks{
-			errEncode: errEncode,
-			errDecode: errDecode,
-		})
+		setStub := func() {
+			extras.Header.Set(hdr, &stubHeaderHooks{
+				errMarshal:   errMarshal,
+				errUnmarshal: errUnmarshal,
+				errEncode:    errEncode,
+				errDecode:    errDecode,
+			})
+		}
+
+		setStub()
+		_, err := json.Marshal(hdr)
+		assert.ErrorIs(t, err, errMarshal, "via json.Marshal()")
+		assert.Equal(t, errUnmarshal, json.Unmarshal([]byte("{}"), hdr), "via json.Unmarshal()")
 
+		setStub() // [stubHeaderHooks] completely overrides the Header
 		assert.Equal(t, errEncode, rlp.Encode(io.Discard, hdr), "via rlp.Encode()")
 		assert.Equal(t, errDecode, rlp.DecodeBytes([]byte{0}, hdr), "via rlp.DecodeBytes()")
 	})