all: add tests for PingRequest implementation

Unit tests for Change (IsEmpty, Merge, Type, PingNode constructor),
ping tracker (register/complete/cancel lifecycle, concurrency, latency),
and end-to-end servertests exercising the full round-trip with real
controlclient.Direct instances.

Updates #2902
Updates #2129

hscontrol/servertest/ping_test.go

@@ -0,0 +1,169 @@
+package servertest_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/juanfont/headscale/hscontrol/servertest"
+	"github.com/juanfont/headscale/hscontrol/types"
+	"github.com/juanfont/headscale/hscontrol/types/change"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"tailscale.com/tailcfg"
+)
+
+// TestPingNode verifies the full ping round-trip: the server sends a
+// PingRequest via MapResponse, the real controlclient.Direct handles it
+// by making a HEAD request back over Noise, and the ping tracker records
+// the latency.
+func TestPingNode(t *testing.T) {
+	t.Parallel()
+
+	h := servertest.NewHarness(t, 1)
+
+	nm := h.Client(0).Netmap()
+	require.NotNil(t, nm)
+	require.True(t, nm.SelfNode.Valid())
+
+	nodeID := types.NodeID(nm.SelfNode.ID()) //nolint:gosec
+
+	st := h.Server.State()
+	pingID, responseCh := st.RegisterPing(nodeID)
+
+	defer st.CancelPing(pingID)
+
+	callbackURL := h.Server.URL + "/machine/ping-response?id=" + pingID
+	h.Server.App.Change(change.PingNode(nodeID, &tailcfg.PingRequest{
+		URL: callbackURL,
+		Log: true,
+	}))
+
+	select {
+	case latency := <-responseCh:
+		assert.Positive(t, latency, "latency should be positive, got %v", latency)
+		assert.Less(t, latency, 10*time.Second, "latency should be reasonable, got %v", latency)
+	case <-time.After(15 * time.Second):
+		t.Fatal("ping response not received within 15s")
+	}
+}
+
+// TestPingDisconnectedNode verifies that pinging a disconnected node
+// results in no response (the channel never receives).
+func TestPingDisconnectedNode(t *testing.T) {
+	t.Parallel()
+
+	h := servertest.NewHarness(t, 1)
+
+	nm := h.Client(0).Netmap()
+	require.NotNil(t, nm)
+
+	nodeID := types.NodeID(nm.SelfNode.ID()) //nolint:gosec
+
+	// Disconnect the client.
+	h.Client(0).Disconnect(t)
+
+	st := h.Server.State()
+	pingID, responseCh := st.RegisterPing(nodeID)
+
+	defer st.CancelPing(pingID)
+
+	callbackURL := h.Server.URL + "/machine/ping-response?id=" + pingID
+	h.Server.App.Change(change.PingNode(nodeID, &tailcfg.PingRequest{
+		URL: callbackURL,
+		Log: true,
+	}))
+
+	select {
+	case <-responseCh:
+		t.Fatal("should not receive response from disconnected node")
+	case <-time.After(3 * time.Second):
+		// Expected: no response.
+	}
+}
+
+// TestPingTwoSameNode verifies that two concurrent pings to the same
+// node complete independently.
+func TestPingTwoSameNode(t *testing.T) {
+	t.Parallel()
+
+	h := servertest.NewHarness(t, 1)
+
+	nm := h.Client(0).Netmap()
+	require.NotNil(t, nm)
+
+	nodeID := types.NodeID(nm.SelfNode.ID()) //nolint:gosec
+
+	st := h.Server.State()
+
+	pingID1, ch1 := st.RegisterPing(nodeID)
+	defer st.CancelPing(pingID1)
+
+	pingID2, ch2 := st.RegisterPing(nodeID)
+	defer st.CancelPing(pingID2)
+
+	require.NotEqual(t, pingID1, pingID2)
+
+	// Send both PingRequests.
+	url1 := h.Server.URL + "/machine/ping-response?id=" + pingID1
+	url2 := h.Server.URL + "/machine/ping-response?id=" + pingID2
+
+	h.Server.App.Change(change.PingNode(nodeID, &tailcfg.PingRequest{
+		URL: url1,
+	}))
+	h.Server.App.Change(change.PingNode(nodeID, &tailcfg.PingRequest{
+		URL: url2,
+	}))
+
+	timeout := time.After(15 * time.Second)
+
+	var got1, got2 bool
+
+	for !got1 || !got2 {
+		select {
+		case latency := <-ch1:
+			assert.GreaterOrEqual(t, latency, time.Duration(0))
+
+			got1 = true
+		case latency := <-ch2:
+			assert.GreaterOrEqual(t, latency, time.Duration(0))
+
+			got2 = true
+		case <-timeout:
+			t.Fatalf("timed out: got1=%v got2=%v", got1, got2)
+		}
+	}
+}
+
+// TestPingResolveByHostname verifies that ResolveNode can find a node
+// by hostname and that the resolved node can be pinged.
+func TestPingResolveByHostname(t *testing.T) {
+	t.Parallel()
+
+	h := servertest.NewHarness(t, 1, servertest.WithDefaultClientOptions(
+		servertest.WithHostname("my-test-host"),
+	))
+
+	st := h.Server.State()
+
+	// Resolve by hostname.
+	node, ok := st.ResolveNode("my-test-host")
+	require.True(t, ok, "should resolve node by hostname")
+
+	nodeID := node.ID()
+
+	pingID, responseCh := st.RegisterPing(nodeID)
+	defer st.CancelPing(pingID)
+
+	callbackURL := h.Server.URL + "/machine/ping-response?id=" + pingID
+	h.Server.App.Change(change.PingNode(nodeID, &tailcfg.PingRequest{
+		URL: callbackURL,
+		Log: true,
+	}))
+
+	select {
+	case latency := <-responseCh:
+		assert.Positive(t, latency)
+	case <-time.After(15 * time.Second):
+		t.Fatal("ping response not received")
+	}
+}