Add initial fuzz tests comparing roundtrip to upstream Go proto

conformance/internal/conformance/fuzz_test.go

@@ -0,0 +1,61 @@
+package conformance
+
+import (
+	"github.com/stretchr/testify/require"
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/encoding/prototext"
+	"google.golang.org/protobuf/proto"
+	"strings"
+	"testing"
+)
+
+func roundTripUpstream(b []byte) ([]byte, error) {
+	msg := &TestAllTypesProto3{}
+	if err := proto.Unmarshal(b, msg); err != nil {
+		return nil, err
+	}
+	res, err := proto.Marshal(msg)
+	if err != nil {
+		return nil, err
+	}
+	return res, nil
+}
+
+func roundTripVtprotobuf(b []byte) ([]byte, error) {
+	msg := &TestAllTypesProto3{}
+	if err := msg.UnmarshalVT(b); err != nil {
+		return nil, err
+	}
+	res, err := msg.MarshalVT()
+	if err != nil {
+		return nil, err
+	}
+	return res, nil
+}
+
+func FuzzProto(f *testing.F) {
+	f.Fuzz(func(t *testing.T, b []byte) {
+		u, uerr := roundTripUpstream(b)
+		v, verr := roundTripVtprotobuf(b)
+		if verr != nil && strings.Contains(verr.Error(), "wrong wireType") {
+			t.Skip()
+		}
+		if uerr != nil && strings.Contains(uerr.Error(), "cannot parse invalid wire-format data") {
+			t.Skip()
+		}
+		if (uerr != nil) != (verr != nil) {
+			t.Fatalf("upstream err: %v (%v), vtprotobuf err: %v (%v)", uerr, u, verr, v)
+		}
+		us := &TestAllTypesProto3{}
+		_ = proto.Unmarshal(b, us)
+		us.unknownFields = nil
+
+		t.Logf("upstream  : %v, %v", protojson.Format(us), prototext.Format(us))
+		vt := &TestAllTypesProto3{}
+		_ = vt.UnmarshalVT(b)
+		vt.unknownFields = nil
+		t.Logf("vtprotobuf: %v, %v", protojson.Format(vt), prototext.Format(vt))
+		require.Equal(t, us, vt)
+		//require.Equal(t, u, v)
+	})
+}

conformance/internal/conformance/testdata/fuzz/FuzzProto/522abd8fab0ae8ff

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("\x89\x89\x0000000000")

conformance/internal/conformance/testdata/fuzz/FuzzProto/f20414dfed3c853c

@@ -0,0 +1,2 @@
+go test fuzz v1
+[]byte("z\x00")