Jacob Vosmaer · 6c9c36eb
--- a/client/dial_test.go
+++ b/client/dial_test.go
+					return err
+				}
+				buf, err := io.ReadAll(conn)
+				if err != nil {
+					return err
+				}
+				if string(buf) != "pong" {
+					return fmt.Errorf("expected pong, got %q", buf)
+				}
+
+				return nil
+			})
+			defer scw.Close()
+
+			req := &healthpb.HealthCheckRequest{Service: "test sidechannel"}
+			_, err = healthpb.NewHealthClient(conn).Check(ctx, req)
--- a/client/sidechannel.go 0 → 100644
+++ b/client/sidechannel.go 0 → 100644
+// value of the callback. If the callback has not been called yet, Close
+// returns an error immediately.
+func (w *SidechannelWaiter) Close() error { return w.waiter.Close() }
+
+// SidechannelConn allows a client to read and write bytes with less
+// overhead than doing so via gRPC messages.
+type SidechannelConn interface {
+	io.ReadWriter
+
+	// CloseWrite tells the server we won't write any more data. We can still
+	// read data from the server after CloseWrite(). A typical use case is in
+	// an RPC where the byte stream has a request/response pattern: the
+	// client then uses CloseWrite() to signal the end of the request body.
+	// When the client calls CloseWrite(), the server receives EOF.
+	CloseWrite() error
+}
--- a/client/sidechannel.go 0 → 100644
+++ b/client/sidechannel.go 0 → 100644
+
+// SidechannelConn allows a client to read and write bytes with less
+// overhead than doing so via gRPC messages.
+type SidechannelConn interface {
+	io.ReadWriter
+
+	// CloseWrite tells the server we won't write any more data. We can still
+	// read data from the server after CloseWrite(). A typical use case is in
+	// an RPC where the byte stream has a request/response pattern: the
+	// client then uses CloseWrite() to signal the end of the request body.
+	// When the client calls CloseWrite(), the server receives EOF.
+	CloseWrite() error
+}
+
+// TestSidechannelServer allows downstream consumers of this package to
+// create mock sidechannel gRPC servers.
--- a/client/dial_test.go
+++ b/client/dial_test.go
 	}
 }

+func TestDialSidechannel(t *testing.T) {
+	if emitProxyWarning() {
+		t.Log("WARNING. Proxy configuration detected from environment settings. This test failure may be related to proxy configuration. Please process with caution")
+	}
+
+	stop, connectionMap := startListeners(t, func(creds credentials.TransportCredentials) *grpc.Server {
+		return grpc.NewServer(TestSidechannelServer(newLogger(t), creds, func(
+			_ interface{},
+			stream grpc.ServerStream,
+			sidechannelConn io.ReadWriteCloser,
+		) error {
+			if method, ok := grpc.Method(stream.Context()); !ok || method != "/grpc.health.v1.Health/Check" {
--- a/client/dial_test.go
+++ b/client/dial_test.go
 	}
 }

+func TestDialSidechannel(t *testing.T) {
+	if emitProxyWarning() {