refactor(gateway): share interface discovery helpers

src/infra/network-interfaces.test.ts

@@ -0,0 +1,47 @@
+import { describe, expect, it } from "vitest";
+import { makeNetworkInterfacesSnapshot } from "../test-helpers/network-interfaces.js";
+import {
+  listExternalInterfaceAddresses,
+  pickMatchingExternalInterfaceAddress,
+  safeNetworkInterfaces,
+} from "./network-interfaces.js";
+
+describe("network-interfaces", () => {
+  it("returns undefined when interface discovery throws", () => {
+    expect(
+      safeNetworkInterfaces(() => {
+        throw new Error("uv_interface_addresses failed");
+      }),
+    ).toBeUndefined();
+  });
+
+  it("lists trimmed non-internal external addresses only", () => {
+    const snapshot = makeNetworkInterfacesSnapshot({
+      lo0: [{ address: "127.0.0.1", family: "IPv4", internal: true }],
+      en0: [
+        { address: " 192.168.1.42 ", family: "IPv4" },
+        { address: "fd7a:115c:a1e0::1", family: "IPv6" },
+        { address: " ", family: "IPv6" },
+      ],
+    });
+
+    expect(listExternalInterfaceAddresses(snapshot)).toEqual([
+      { name: "en0", address: "192.168.1.42", family: "IPv4" },
+      { name: "en0", address: "fd7a:115c:a1e0::1", family: "IPv6" },
+    ]);
+  });
+
+  it("prefers configured interface names before falling back", () => {
+    const snapshot = makeNetworkInterfacesSnapshot({
+      wlan0: [{ address: "172.16.0.99", family: "IPv4" }],
+      en0: [{ address: "192.168.1.42", family: "IPv4" }],
+    });
+
+    expect(
+      pickMatchingExternalInterfaceAddress(snapshot, {
+        family: "IPv4",
+        preferredNames: ["en0", "eth0"],
+      }),
+    ).toBe("192.168.1.42");
+  });
+});