diff --git a/cmd/geth/les_test.go b/cmd/geth/les_test.go
new file mode 100644
index 0000000000..f7a484cf63
--- /dev/null
+++ b/cmd/geth/les_test.go
@@ -0,0 +1,247 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+/*
+var rpcArgs = []string{"--rpc", "--rpcapi=admin,eth,les"}
+
+var port int = 30303
+var rpcPort int = 8545
+
+type gethNode struct {
+	datadir string
+	args    []string
+	cmd     *exec.Cmd
+	rpc     *rpc.Client
+}
+
+func startGeth(datadir string, keepDatadir bool, args ...string) (*gethNode, error) {
+	g := &gethNode{datadir, args, nil, nil}
+	if !keepDatadir {
+		err := os.RemoveAll(datadir)
+		if err != nil {
+			return g, err
+		}
+	}
+	allArgs := []string{"--datadir", datadir, "--port", fmt.Sprintf("%d", port), "--rpcport", fmt.Sprintf("%d", rpcPort)}
+	port += 1
+	rpcPort += 1
+	allArgs = append(allArgs, rpcArgs...)
+	allArgs = append(allArgs, args...)
+	cmd := exec.Command("geth", allArgs...)
+	log.Println("to start", cmd.String())
+	var err error
+	cmd.Stderr = os.Stderr
+	err = cmd.Start()
+	if err != nil {
+		return nil, err
+	}
+	g.cmd = cmd
+	time.Sleep(1 * time.Second) // wait before we can attach to it
+	// TODO: probe for it properly
+	g.rpc, err = rpc.Dial(g.ipcpath())
+	if err != nil {
+		return nil, err
+	}
+	return g, nil
+}
+
+
+// Start and wait for it to finish
+func runGeth(datadir string, keepDatadir bool, args ...string) error {
+	if !keepDatadir {
+		if err := os.RemoveAll(datadir); err != nil {
+			return err
+		}
+	}
+	allArgs := []string{"--datadir", datadir}
+	allArgs = append(allArgs, args...)
+	cmd := exec.Command("geth", allArgs...)
+	log.Println("to run", cmd.String())
+	cmd.Stderr = os.Stderr
+	if err := cmd.Start(); err != nil {
+		return fmt.Errorf("starting but %s", err)
+	}
+	if err := cmd.Wait(); err != nil {
+		return fmt.Errorf("waiting but %s", err)
+	}
+	return nil
+}
+
+func (g *gethNode) ipcpath() string {
+	return filepath.Join(g.datadir, "geth.ipc")
+}
+
+func (g *gethNode) kill() error {
+	err := g.cmd.Process.Kill()
+	if err != nil {
+		return err
+	}
+	_, err = g.cmd.Process.Wait()
+	return err
+}
+
+func (g *gethNode) addPeer(enode string) error {
+	peerCh := make(chan *p2p.PeerEvent)
+	sub, err := g.rpc.Subscribe(context.Background(), "admin", peerCh, "peerEvents")
+	if err != nil {
+		return fmt.Errorf("subscribe: %v", err)
+	}
+	defer sub.Unsubscribe()
+	if err := g.rpc.Call(nil, "admin_addPeer", enode); err != nil {
+		return fmt.Errorf("admin_addPeer: %v", err)
+	}
+	select {
+	case ev := <-peerCh:
+		fmt.Print("event", ev)
+
+	case err := <-sub.Err():
+		return fmt.Errorf("notification: %v", err)
+	}
+	return nil
+}
+
+func (g *gethNode) waitSynced() error {
+	ch := make(chan interface{})
+	sub, err := g.rpc.Subscribe(context.Background(), "eth", ch, "syncing")
+	if err != nil {
+		return fmt.Errorf("syncing: %v", err)
+	}
+	defer sub.Unsubscribe()
+	timeout := time.After(40 * time.Second)
+	for {
+		select {
+		case ev := <-ch:
+			syncing, ok := ev.(bool)
+			if ok && !syncing {
+				return nil
+			}
+		case err := <-sub.Err():
+			return fmt.Errorf("notification: %v", err)
+		case <-timeout:
+			return fmt.Errorf("timeout syncing")
+		}
+	}
+}
+*/
+
+func startLightServer(t *testing.T) *rpc.Client {
+	// Create a temporary data directory to use
+	datadir := tmpdir(t)
+	defer os.RemoveAll(datadir)
+	ipcpath := filepath.Join(datadir, "geth.ipc")
+
+	t.Log("server datadir", datadir)
+	runGeth(t, "--datadir", datadir, "init", "./testdata/genesis.json").WaitExit()
+	t.Log("init done")
+	runGeth(t, "--datadir", datadir, "--gcmode=archive", "import", "./testdata/blockchain.blocks").WaitExit()
+	t.Log("import done")
+	geth := runGeth(t, "--datadir", datadir, "--networkid=42", "--port=0", "--rpcport=0", "--rpc", "--rpcapi=admin,eth,les", "--light.serve=100", "--light.maxpeers=1", "--nodiscover", "--nat=extip:127.0.0.1")
+	defer geth.WaitExit()
+	defer geth.Kill()
+	t.Log("started lightserver")
+
+	// wait before we can attach to it. TODO: probe for it properly
+	time.Sleep(1 * time.Second)
+	rpc, err := rpc.Dial(ipcpath)
+	if err != nil {
+		t.Fatalf("rpc connect: %v", err)
+	}
+	return rpc
+}
+
+func TestPriorityClient(t *testing.T) {
+	// Init and start server
+	server := startLightServer(t)
+	nodeInfo := make(map[string]interface{})
+	if err := server.Call(&nodeInfo, "admin_nodeInfo"); err != nil {
+		t.Fatal("nodeInfo:", err)
+	}
+	enode := nodeInfo["enode"].(string)
+	t.Log("enode", enode)
+	/*
+		if err := runGeth(datadir, true, "--gcmode=archive", "import", "./initdata/testBlockchain.blocks"); err != nil {
+			t.Fatal("import", err)
+		}
+		t.Log("import done")
+		server, err := startGeth(datadir, true, "--networkid=42", "--light.serve=100", "--light.maxpeers=1", "--nodiscover", "--nat=extip:127.0.0.1")
+		defer server.kill()
+		if err != nil {
+			t.Fatal("start server", err)
+		}
+		nodeInfo := make(map[string]interface{})
+		if err := server.rpc.Call(&nodeInfo, "admin_nodeInfo"); err != nil {
+			t.Fatal("nodeInfo:", err)
+		}
+		enode := nodeInfo["enode"].(string)
+		t.Log("enode", enode)
+
+		// Client
+		clientdir := "/tmp/client"
+		if err := runGeth(clientdir, false, "init", "./initdata/testGenesis.json"); err != nil {
+			t.Fatal("init client", err)
+		}
+		client, err := startGeth(clientdir, true, "--networkid=42", "--syncmode=light", "--nodiscover")
+		defer client.kill()
+		if err != nil {
+			t.Fatal("start client", err)
+		}
+		if err := client.addPeer(enode); err != nil {
+			t.Fatal("addPeer", err)
+		}
+		var peers []interface{}
+		if err := client.rpc.Call(&peers, "admin_peers"); err != nil {
+			t.Fatal("peers", err)
+		}
+		if len(peers) != 1 {
+			t.Log("Expected: # of client peers == 1")
+			t.Fail()
+		}
+
+		// Priority client
+		priodir := "/tmp/prio"
+		if err := runGeth(priodir, false, "init", "./initdata/testGenesis.json"); err != nil {
+			t.Fatal("init prio", err)
+		}
+		prio, err := startGeth(priodir, true, "--networkid=42", "--syncmode=light", "--nodiscover")
+		defer prio.kill()
+		if err != nil {
+			t.Fatal(prio.cmd.String(), err)
+		}
+		prioNodeInfo := make(map[string]interface{})
+		if err := prio.rpc.Call(&prioNodeInfo, "admin_nodeInfo"); err != nil {
+			t.Fatal("prio nodeInfo:", err)
+		}
+		nodeID := prioNodeInfo["id"].(string)
+		t.Log("nodeID", nodeID)
+		tokens := 3_000_000_000
+		if err := server.rpc.Call(nil, "les_addBalance", nodeID, tokens, "foobar"); err != nil {
+			t.Fatal("addBalance:", err)
+		}
+		if err := prio.addPeer(enode); err != nil {
+			t.Fatal("addPeer", err)
+		}
+
+		// Check if priority client is actually syncing and the regular client got kicked out
+		if err := prio.rpc.Call(&peers, "admin_peers"); err != nil {
+			t.Fatal("prio peers", err)
+		}
+		if len(peers) != 1 {
+			t.Fatal("Expected: # of prio peers == 1")
+		}
+
+		if err := client.rpc.Call(&peers, "admin_peers"); err != nil {
+			t.Fatal("client peers", err)
+		}
+		if len(peers) > 0 {
+			t.Fatal("Expected: # of client peers == 0")
+		}
+	*/
+}
diff --git a/cmd/geth/testdata/blockchain.blocks b/cmd/geth/testdata/blockchain.blocks
new file mode 100644
index 0000000000..d29453d3e5
Binary files /dev/null and b/cmd/geth/testdata/blockchain.blocks differ
diff --git a/cmd/geth/testdata/genesis.json b/cmd/geth/testdata/genesis.json
new file mode 100644
index 0000000000..e77446ed05
--- /dev/null
+++ b/cmd/geth/testdata/genesis.json
@@ -0,0 +1,34 @@
+{
+    "version": "1",
+    "params":{
+        "petersburgForkBlock":"0x0",
+        "chainId":"0xdeadbeef",
+        "miningMethod":"ethash"
+     },
+     "genesis":{
+        "author":"0x0000000000000000000000000000000000000000",
+        "difficulty":"0x1",
+        "extraData":"0xdeadbeef",
+        "gasLimit":"0x900000",
+        "nonce":"0x00000000deadbeef",
+        "timestamp":"0x0"
+     },
+    "config": {
+        "chainId": 42,
+        "ethash": {
+        }
+    },
+    "parentHash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
+    "coinbase"   : "0x8888f1f195afa192cfee860698584c030f4c9db1",
+    "difficulty" : "0x020000",
+    "gasLimit"   : "0x2fefd8",
+    "timestamp"  : "0x54c98c81",
+    "extraData"  : "0x42",
+    "mixHash"    : "0x2c85bcbce56429100b2108254bb56906257582aeafcbd682bc9af67a9f5aee46",
+    "nonce"      : "0x78cc16f7b4f65485",
+    "alloc"      : {
+        "a94f5374fce5edbc8e2a8697c15331677e6ebf0b": {
+            "balance" : "0x09184e72a000"
+        }
+    }
+}
\ No newline at end of file