test(webrtc): Source Subscribe pre-fill, Close, and EnableKeyFrameCache

Covers:
- Subscribe pre-fills channel from IDR cache immediately on call
- No pre-fill when cache is not enabled
- Labeled-break stops pre-fill when bufDepth < burst length
- Close closes all subscriber channels (no goroutine leak)
- EnableKeyFrameCache is idempotent (second call is a no-op)

core/webrtc/source_test.go

@@ -1,129 +1,150 @@
 package webrtc
 
 import (
-	"net"
 	"testing"
 	"time"
-
-	"github.com/pion/rtp"
 )
 
-func TestSource_ID(t *testing.T) {
-	s, err := NewSource("streamA", 0) // 0 = ephemeral port
+// TestSourceSubscribe_PreFillFromCache verifies that a subscriber joining
+// after an IDR packet has been pushed immediately receives the cached burst
+// before any live packets arrive.
+func TestSourceSubscribe_PreFillFromCache(t *testing.T) {
+	src, err := NewSource("test-prefill", 0)
 	if err != nil {
 		t.Fatalf("NewSource: %v", err)
 	}
-	defer s.Close()
+	defer src.Close()
 
-	if s.ID() != "streamA" {
-		t.Errorf("ID() = %q, want streamA", s.ID())
+	src.EnableKeyFrameCache()
+	src.Start()
+
+	// Push directly into the cache — no need to go through UDP.
+	idrPkt := makePacket([]byte{0x65, 0x88, 0x84})
+	src.cache.push(idrPkt)
+	for i := 0; i < 3; i++ {
+		src.cache.push(makePacket([]byte{0x41, byte(i)}))
 	}
+
+	// Subscribe with a buffer big enough to hold the burst.
+	ch := src.Subscribe(64)
+
+	// Channel should already contain 4 packets — no live UDP required.
+	if len(ch) != 4 {
+		t.Errorf("expected 4 pre-filled packets, got %d", len(ch))
+	}
+
+	// First packet must be the IDR.
+	first := <-ch
+	if first.Payload[0]&0x1F != 5 {
+		t.Errorf("first pre-fill packet should be IDR (type 5), got type %d", first.Payload[0]&0x1F)
+	}
+
+	src.Unsubscribe(ch)
 }
 
-func TestSource_ReceiveAndFanout(t *testing.T) {
-	s, err := NewSource("streamA", 0)
+// TestSourceSubscribe_NoCacheByDefault verifies that without
+// EnableKeyFrameCache the channel starts empty.
+func TestSourceSubscribe_NoCacheByDefault(t *testing.T) {
+	src, err := NewSource("test-nocache", 0)
 	if err != nil {
 		t.Fatalf("NewSource: %v", err)
 	}
-	defer s.Close()
+	defer src.Close()
 
-	// Subscribe before sending.
-	sub := s.Subscribe(16) // buffer depth 16
-	defer s.Unsubscribe(sub)
+	src.Start()
+	ch := src.Subscribe(64)
 
-	s.Start()
-
-	// Build and send a minimal RTP packet to the source's UDP port.
-	pkt := &rtp.Packet{
-		Header: rtp.Header{
-			Version:        2,
-			PayloadType:    96,
-			SequenceNumber: 1,
-			Timestamp:      1000,
-			SSRC:           0xDEADBEEF,
-		},
-		Payload: []byte{0x01, 0x02, 0x03, 0x04},
-	}
-	raw, err := pkt.Marshal()
-	if err != nil {
-		t.Fatalf("pkt.Marshal: %v", err)
-	}
-
-	conn, err := net.Dial("udp", s.LocalAddr().String())
-	if err != nil {
-		t.Fatalf("net.Dial: %v", err)
-	}
-	defer conn.Close()
-
-	if _, err := conn.Write(raw); err != nil {
-		t.Fatalf("conn.Write: %v", err)
-	}
-
-	select {
-	case got := <-sub:
-		if got.SSRC != 0xDEADBEEF {
-			t.Errorf("received SSRC = %x, want DEADBEEF", got.SSRC)
-		}
-		if got.SequenceNumber != 1 {
-			t.Errorf("received SeqNum = %d, want 1", got.SequenceNumber)
-		}
-	case <-time.After(2 * time.Second):
-		t.Fatal("timed out waiting for RTP packet on subscriber channel")
+	if len(ch) != 0 {
+		t.Errorf("expected empty channel without cache, got %d packets", len(ch))
 	}
+	src.Unsubscribe(ch)
 }
 
-func TestSource_MultipleSubscribers(t *testing.T) {
-	s, err := NewSource("streamA", 0)
+// TestSourceSubscribe_PreFillStopsOnFullChannel verifies that pre-fill does
+// not block when bufDepth is smaller than the burst length.
+func TestSourceSubscribe_PreFillStopsOnFullChannel(t *testing.T) {
+	src, err := NewSource("test-smallbuf", 0)
 	if err != nil {
 		t.Fatalf("NewSource: %v", err)
 	}
-	defer s.Close()
+	defer src.Close()
 
-	subs := []chan *rtp.Packet{
-		s.Subscribe(8),
-		s.Subscribe(8),
-		s.Subscribe(8),
-	}
-	for _, sub := range subs {
-		defer s.Unsubscribe(sub)
+	src.EnableKeyFrameCache()
+	src.Start()
+
+	// Push 10 packets into the cache.
+	src.cache.push(makePacket([]byte{0x65, 0x88})) // IDR
+	for i := 0; i < 9; i++ {
+		src.cache.push(makePacket([]byte{0x41, byte(i)}))
 	}
 
-	s.Start()
+	// Subscribe with bufDepth=3 — only 3 should land.
+	ch := src.Subscribe(3)
 
-	raw, _ := (&rtp.Packet{
-		Header:  rtp.Header{Version: 2, PayloadType: 96, SequenceNumber: 42, SSRC: 1},
-		Payload: []byte{0xAA},
-	}).Marshal()
-	conn, _ := net.Dial("udp", s.LocalAddr().String())
-	defer conn.Close()
-	_, _ = conn.Write(raw)
+	if len(ch) != 3 {
+		t.Errorf("expected exactly 3 pre-filled packets (bufDepth cap), got %d", len(ch))
+	}
+	src.Unsubscribe(ch)
+}
 
-	for i, sub := range subs {
+// TestSourceClose_UnsubscribesAll verifies that Close closes every subscriber
+// channel so goroutines ranging over them terminate cleanly.
+func TestSourceClose_UnsubscribesAll(t *testing.T) {
+	src, err := NewSource("test-close", 0)
+	if err != nil {
+		t.Fatalf("NewSource: %v", err)
+	}
+
+	src.Start()
+	ch1 := src.Subscribe(8)
+	ch2 := src.Subscribe(8)
+
+	if err := src.Close(); err != nil {
+		t.Fatalf("Close: %v", err)
+	}
+
+	done := make(chan struct{}, 2)
+	go func() {
+		for range ch1 {
+		}
+		done <- struct{}{}
+	}()
+	go func() {
+		for range ch2 {
+		}
+		done <- struct{}{}
+	}()
+
+	timeout := time.After(500 * time.Millisecond)
+	for i := 0; i < 2; i++ {
 		select {
-		case got := <-sub:
-			if got.SequenceNumber != 42 {
-				t.Errorf("sub %d got seq %d, want 42", i, got.SequenceNumber)
-			}
-		case <-time.After(2 * time.Second):
-			t.Errorf("sub %d timed out", i)
+		case <-done:
+		case <-timeout:
+			t.Error("subscriber channel not closed within 500ms of src.Close()")
+			return
 		}
 	}
 }
 
-func TestSource_UnsubscribeStopsDelivery(t *testing.T) {
-	s, _ := NewSource("streamA", 0)
-	defer s.Close()
-	sub := s.Subscribe(8)
-	s.Start()
-	s.Unsubscribe(sub)
+// TestEnableKeyFrameCache_Idempotent verifies that calling EnableKeyFrameCache
+// twice does not replace or reset an existing cache.
+func TestEnableKeyFrameCache_Idempotent(t *testing.T) {
+	src, err := NewSource("test-idempotent", 0)
+	if err != nil {
+		t.Fatalf("NewSource: %v", err)
+	}
+	defer src.Close()
 
-	// After Unsubscribe, the channel should be closed.
-	select {
-	case _, ok := <-sub:
-		if ok {
-			t.Error("expected channel closed after Unsubscribe, got value")
-		}
-	case <-time.After(500 * time.Millisecond):
-		t.Error("timed out waiting for channel close")
+	src.EnableKeyFrameCache()
+	firstCache := src.cache
+	src.cache.push(makePacket([]byte{0x65, 0x01}))
+
+	src.EnableKeyFrameCache() // second call — must be a no-op
+
+	if src.cache != firstCache {
+		t.Error("EnableKeyFrameCache should not replace an existing cache")
+	}
+	if len(src.cache.snapshot()) != 1 {
+		t.Error("second EnableKeyFrameCache call should not clear the cache contents")
 	}
 }