import * as Net from "node:net"; import { assert, describe, it } from "@effect/vitest";import { Effect } from "effect"; import { NetError, NetService } from "./Net.ts"; const closeServer = (server: Net.Server) =>  Effect.sync(() => {    try {      server.close();    } catch {      // Ignore cleanup failures in tests.    }  }); const getPort = (server: Net.Server): number => {  const address = server.address();  return typeof address === "object" && address !== null ? address.port : 0;}; const openServer = (host?: string): Effect.Effect<Net.Server, NetError> =>  Effect.callback<Net.Server, NetError>((resume) => {    const server = Net.createServer();    let settled = false;     const settle = (effect: Effect.Effect<Net.Server, NetError>) => {      if (settled) return;      settled = true;      resume(effect);    };     server.once("error", (cause) => {      settle(Effect.fail(new NetError({ message: "Failed to open test server", cause })));    });     if (host) {      server.listen(0, host, () => settle(Effect.succeed(server)));    } else {      server.listen(0, () => settle(Effect.succeed(server)));    }     return closeServer(server);  }); it.layer(NetService.layer)("NetService", (it) => {  describe("Net helpers", () => {    it.effect("reserveLoopbackPort returns a positive loopback port", () =>      Effect.gen(function* () {        const net = yield* NetService;        const port = yield* net.reserveLoopbackPort();         assert.ok(port > 0);      }),    );     it.effect("isPortAvailableOnLoopback reports false for an occupied port", () =>      Effect.acquireUseRelease(        openServer("127.0.0.1"),        (server) =>          Effect.gen(function* () {            const net = yield* NetService;            const port = getPort(server);             const available = yield* net.isPortAvailableOnLoopback(port);            assert.equal(available, false);          }),        closeServer,      ),    );     it.effect("findAvailablePort returns preferred when it is free", () =>      Effect.gen(function* () {        const net = yield* NetService;        const preferred = yield* net.reserveLoopbackPort();         const resolved = yield* net.findAvailablePort(preferred);        assert.equal(resolved, preferred);      }),    );     it.effect("findAvailablePort falls back when preferred is occupied", () =>      Effect.acquireUseRelease(        openServer(),        (server) =>          Effect.gen(function* () {            const net = yield* NetService;            const preferred = getPort(server);             const resolved = yield* net.findAvailablePort(preferred);            assert.ok(resolved > 0);            assert.notEqual(resolved, preferred);          }),        closeServer,      ),    );  });});