v3 refactor (#1868)

* Move to v3

Co-authored-by: Ben Toogood <bentoogood@gmail.com>

server/mucp/rpc_codec_test.go

@@ -0,0 +1,109 @@
+package mucp
+
+import (
+	"bytes"
+	"errors"
+	"testing"
+
+	"github.com/micro/go-micro/v3/codec"
+	"github.com/micro/go-micro/v3/transport"
+)
+
+// testCodec is a dummy codec that only knows how to encode nil bodies
+type testCodec struct {
+	buf *bytes.Buffer
+}
+
+type testSocket struct {
+	local  string
+	remote string
+}
+
+// TestCodecWriteError simulates what happens when a codec is unable
+// to encode a message (e.g. a missing branch of an "oneof" message in
+// protobufs)
+//
+// We expect an error to be sent to the socket. Previously the socket
+// would remain open with no bytes sent, leading to client-side
+// timeouts.
+func TestCodecWriteError(t *testing.T) {
+	socket := testSocket{}
+	message := transport.Message{
+		Header: map[string]string{},
+		Body:   []byte{},
+	}
+
+	rwc := readWriteCloser{
+		rbuf: new(bytes.Buffer),
+		wbuf: new(bytes.Buffer),
+	}
+
+	c := rpcCodec{
+		buf: &rwc,
+		codec: &testCodec{
+			buf: rwc.wbuf,
+		},
+		req:    &message,
+		socket: socket,
+	}
+
+	err := c.Write(&codec.Message{
+		Endpoint: "Service.Endpoint",
+		Id:       "0",
+		Error:    "",
+	}, "body")
+
+	if err != nil {
+		t.Fatalf(`Expected Write to fail; got "%+v" instead`, err)
+	}
+
+	const expectedError = "Unable to encode body: simulating a codec write failure"
+	actualError := rwc.wbuf.String()
+	if actualError != expectedError {
+		t.Fatalf(`Expected error "%+v" in the write buffer, got "%+v" instead`, expectedError, actualError)
+	}
+}
+
+func (c *testCodec) ReadHeader(message *codec.Message, typ codec.MessageType) error {
+	return nil
+}
+
+func (c *testCodec) ReadBody(dest interface{}) error {
+	return nil
+}
+
+func (c *testCodec) Write(message *codec.Message, dest interface{}) error {
+	if dest != nil {
+		return errors.New("simulating a codec write failure")
+	}
+	c.buf.Write([]byte(message.Error))
+	return nil
+}
+
+func (c *testCodec) Close() error {
+	return nil
+}
+
+func (c *testCodec) String() string {
+	return "string"
+}
+
+func (s testSocket) Local() string {
+	return s.local
+}
+
+func (s testSocket) Remote() string {
+	return s.remote
+}
+
+func (s testSocket) Recv(message *transport.Message) error {
+	return nil
+}
+
+func (s testSocket) Send(message *transport.Message) error {
+	return nil
+}
+
+func (s testSocket) Close() error {
+	return nil
+}