1 files changed, 48 insertions, 0 deletions
diff --git a/p2p/nat/nat_test.go b/p2p/nat/nat_test.go
new file mode 100644
index 000000000..95c50522e
--- /dev/null
+++ b/p2p/nat/nat_test.go
@@ -0,0 +1,48 @@
+package nat
+
+import (
+	"bytes"
+	"net"
+	"testing"
+	"time"
+)
+
+// This test checks that autodisc doesn't hang and returns
+// consistent results when multiple goroutines call its methods
+// concurrently.
+func TestAutoDiscRace(t *testing.T) {
+	ad := startautodisc("thing", func() Interface {
+		time.Sleep(500 * time.Millisecond)
+		return extIP{33, 44, 55, 66}
+	})
+
+	// Spawn a few concurrent calls to ad.ExternalIP.
+	type rval struct {
+		ip  net.IP
+		err error
+	}
+	results := make(chan rval, 50)
+	for i := 0; i < cap(results); i++ {
+		go func() {
+			ip, err := ad.ExternalIP()
+			results <- rval{ip, err}
+		}()
+	}
+
+	// Check that they all return the correct result within the deadline.
+	deadline := time.After(550 * time.Millisecond)
+	for i := 0; i < cap(results); i++ {
+		select {
+		case <-deadline:
+			t.Fatal("deadline exceeded")
+		case rval := <-results:
+			if rval.err != nil {
+				t.Errorf("result %d: unexpected error: %v", i, rval.err)
+			}
+			wantIP := net.IP{33, 44, 55, 66}
+			if !bytes.Equal(rval.ip, wantIP) {
+				t.Errorf("result %d: got IP %v, want %v", i, rval.ip, wantIP)
+			}
+		}
+	}
+}