diff --git a/peer/state-client_test.go b/peer/state-client_test.go
new file mode 100644
index 0000000..8feb4d2
--- /dev/null
+++ b/peer/state-client_test.go
@@ -0,0 +1,34 @@
+package peer
+
+import "testing"
+
+func TestStateClient_peerUpdate(t *testing.T) {
+	h := NewPeerStateTestHarness()
+	h.ConfigClientDirect(t)
+	h.PeerUpdate(nil)
+	assertType[*stateDisconnected](t, h.State)
+}
+
+func TestStateClient_initialPackets(t *testing.T) {
+	h := NewPeerStateTestHarness()
+	h.ConfigClientDirect(t)
+
+	assertEqual(t, len(h.Sent), 2)
+	assertType[packetInit](t, h.Sent[0].Packet)
+	assertType[packetSyn](t, h.Sent[1].Packet)
+}
+
+func TestStateClient_onAck_incorrectTraceID(t *testing.T) {
+	h := NewPeerStateTestHarness()
+	h.ConfigClientDirect(t)
+	h.Sent = h.Sent[:0]
+
+	ack := controlMsg[packetAck]{
+		Packet: packetAck{TraceID: newTraceID()},
+	}
+	h.OnAck(ack)
+
+	// Nothing should have happened.
+	assertType[*stateClient](t, h.State)
+	assertEqual(t, len(h.Sent), 0)
+}