diff --git a/mtglib/internal/relay/conn_internal_test.go b/mtglib/internal/relay/conn_internal_test.go
new file mode 100644
index 0000000..0514767
--- /dev/null
+++ b/mtglib/internal/relay/conn_internal_test.go
@@ -0,0 +1,125 @@
+package relay
+
+import (
+	"context"
+	"errors"
+	"io"
+	"testing"
+
+	"github.com/9seconds/mtg/v2/testlib"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/suite"
+)
+
+type ConnTestSuite struct {
+	suite.Suite
+
+	ctxCancel   context.CancelFunc
+	connMock    *testlib.NetConnMock
+	tickChannel chan struct{}
+	buf         []byte
+	c           conn
+}
+
+func (suite *ConnTestSuite) SetupTest() {
+	ctx, cancel := context.WithCancel(context.Background())
+
+	suite.tickChannel = make(chan struct{}, 1)
+	suite.connMock = &testlib.NetConnMock{}
+	suite.ctxCancel = cancel
+	suite.buf = make([]byte, 5)
+
+	suite.c = conn{
+		ReadWriteCloser: suite.connMock,
+		ctx:             ctx,
+		tickChannel:     suite.tickChannel,
+	}
+}
+
+func (suite *ConnTestSuite) TestReadOk() {
+	suite.connMock.On("Read", mock.Anything).Once().Return(len(suite.buf), nil)
+
+	n, err := suite.c.Read(suite.buf)
+	suite.NoError(err)
+	suite.Equal(len(suite.buf), n)
+
+	select {
+	case <-suite.tickChannel:
+	default:
+		suite.FailNow("cannot find a tick event")
+	}
+}
+
+func (suite *ConnTestSuite) TestReadErr() {
+	suite.connMock.On("Read", mock.Anything).Once().Return(0, io.EOF)
+
+	_, err := suite.c.Read(suite.buf)
+	suite.True(errors.Is(err, io.EOF))
+
+	select {
+	case <-suite.tickChannel:
+	default:
+		suite.FailNow("cannot find a tick event")
+	}
+}
+
+func (suite *ConnTestSuite) TestReadContextDone() {
+	suite.connMock.On("Read", mock.Anything).Once().Return(len(suite.buf), nil)
+	suite.ctxCancel()
+
+	suite.tickChannel <- struct{}{}
+
+	suite.c.Read(suite.buf)
+}
+
+func (suite *ConnTestSuite) TestWriteOk() {
+	suite.connMock.On("Write", mock.Anything).Once().Return(len(suite.buf), nil)
+
+	n, err := suite.c.Write(suite.buf)
+	suite.NoError(err)
+	suite.Equal(len(suite.buf), n)
+
+	select {
+	case <-suite.tickChannel:
+	default:
+		suite.FailNow("cannot find a tick event")
+	}
+}
+
+func (suite *ConnTestSuite) TestWriteErr() {
+	suite.connMock.On("Write", mock.Anything).Once().Return(0, io.EOF)
+
+	_, err := suite.c.Write(suite.buf)
+	suite.True(errors.Is(err, io.EOF))
+
+	select {
+	case <-suite.tickChannel:
+	default:
+		suite.FailNow("cannot find a tick event")
+	}
+}
+
+func (suite *ConnTestSuite) TestWriteContextDone() {
+	suite.connMock.On("Write", mock.Anything).Once().Return(len(suite.buf), nil)
+	suite.ctxCancel()
+
+	suite.tickChannel <- struct{}{}
+
+	suite.c.Write(suite.buf)
+}
+
+func (suite *ConnTestSuite) TearDownTest() {
+	select {
+	case <-suite.tickChannel:
+	default:
+	}
+
+	close(suite.tickChannel)
+
+	suite.connMock.AssertExpectations(suite.T())
+}
+
+func TestConn(t *testing.T) {
+	t.Parallel()
+	suite.Run(t, &ConnTestSuite{})
+}