From 841335d14b34705162f2e59df08ae80be2c424cb Mon Sep 17 00:00:00 2001
From: ZGaetano <zgaetano@wilddragon.net>
Date: Sun, 10 May 2026 14:02:10 -0400
Subject: [PATCH] webrtc: add NAT1To1IPs multi-IP and fallback tests (issue
 #20)

---
 core/webrtc/ice_test.go | 73 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/core/webrtc/ice_test.go b/core/webrtc/ice_test.go
index 99294c1..63f21a3 100644
--- a/core/webrtc/ice_test.go
+++ b/core/webrtc/ice_test.go
@@ -48,3 +48,76 @@ func TestBuildICEConfig_InvalidConfig(t *testing.T) {
 		t.Error("BuildICEConfig should reject invalid config")
 	}
 }
+
+// TestBuildICEConfig_NAT1To1IPs_Multi verifies that a list of multiple
+// NAT1To1 IPs is accepted and a SettingEngine is returned, allowing
+// dual-homed servers to advertise host candidates on all interfaces.
+func TestBuildICEConfig_NAT1To1IPs_Multi(t *testing.T) {
+	c := DefaultConfig()
+	c.NAT1To1IPs = []string{"10.0.0.1", "203.0.113.10"}
+	_, se, err := BuildICEConfig(c)
+	if err != nil {
+		t.Fatalf("BuildICEConfig with multiple NAT1To1IPs: %v", err)
+	}
+	if se == nil {
+		t.Fatal("SettingEngine should not be nil when NAT1To1IPs is set")
+	}
+	// Smoke-test: Pion should accept the engine without panicking.
+	api := webrtc.NewAPI(webrtc.WithSettingEngine(*se))
+	if api == nil {
+		t.Fatal("NewAPI returned nil")
+	}
+}
+
+// TestBuildICEConfig_NAT1To1IPs_FallsBackToPublicIP verifies that when
+// NAT1To1IPs is empty but PublicIP is set, the single IP is promoted to
+// the NAT1To1 list (backward-compat path).
+func TestBuildICEConfig_NAT1To1IPs_FallsBackToPublicIP(t *testing.T) {
+	c := DefaultConfig()
+	c.PublicIP = "198.51.100.1"
+	c.NAT1To1IPs = nil
+	_, se, err := BuildICEConfig(c)
+	if err != nil {
+		t.Fatalf("BuildICEConfig (PublicIP fallback): %v", err)
+	}
+	if se == nil {
+		t.Fatal("SettingEngine should be set when PublicIP is used as fallback")
+	}
+}
+
+// TestBuildICEConfig_NAT1To1IPs_TakesPrecedenceOverPublicIP verifies that
+// when both NAT1To1IPs and PublicIP are set, a SettingEngine is still
+// returned (the subsystem merges them; BuildICEConfig sees only NAT1To1IPs).
+func TestBuildICEConfig_NAT1To1IPs_TakesPrecedenceOverPublicIP(t *testing.T) {
+	c := DefaultConfig()
+	c.PublicIP = "198.51.100.1"
+	c.NAT1To1IPs = []string{"10.0.0.1", "198.51.100.1"}
+	_, se, err := BuildICEConfig(c)
+	if err != nil {
+		t.Fatalf("BuildICEConfig (NAT1To1IPs + PublicIP): %v", err)
+	}
+	if se == nil {
+		t.Fatal("SettingEngine should not be nil when NAT1To1IPs is set")
+	}
+}
+
+// TestBuildICEConfig_NAT1To1IPs_NeitherSet verifies that with no IP hints
+// the function still succeeds (STUN-only mode). A SettingEngine is still
+// returned because the default UDPPortRange is non-zero.
+func TestBuildICEConfig_NAT1To1IPs_NeitherSet(t *testing.T) {
+	c := DefaultConfig()
+	c.PublicIP = ""
+	c.NAT1To1IPs = nil
+	_, se, err := BuildICEConfig(c)
+	if err != nil {
+		t.Fatalf("BuildICEConfig (STUN-only): %v", err)
+	}
+	// UDPPortRange.Low > 0 in DefaultConfig, so se is non-nil; verify it
+	// builds without error.
+	if se != nil {
+		api := webrtc.NewAPI(webrtc.WithSettingEngine(*se))
+		if api == nil {
+			t.Fatal("NewAPI returned nil in STUN-only mode")
+		}
+	}
+}