useSee.test.ts

import { renderHook, act } from "@testing-library/react";
import { vi } from "vitest";
import { useSse } from "../useSse";
import { TestQueryClientProvider } from "@/lib/test-utils";

vi.mock("react-router-dom", () => ({
  useLocation: vi.fn(() => ({ pathname: "/" })),
}));

const mockInvalidate = vi.fn();

vi.mock("@tanstack/react-query", async () => {
  const original = await vi.importActual<
    typeof import("@tanstack/react-query")
  >("@tanstack/react-query");
  return {
    ...original,
    useQueryClient: () => ({
      invalidateQueries: mockInvalidate,
    }),
  };
});

class MockEventSource {
  static instances: MockEventSource[] = [];
  private _onmessage: ((event: MessageEvent) => void) | null = null;

  constructor() {
    MockEventSource.instances.push(this);
  }

  get onmessage() {
    return this._onmessage;
  }

  set onmessage(handler: ((event: MessageEvent) => void) | null) {
    this._onmessage = handler;
  }

  close() {}

  static triggerMessage(data: string) {
    MockEventSource.instances.forEach((instance) => {
      if (instance.onmessage) {
        instance.onmessage({ data } as MessageEvent);
      }
    });
  }
}

let originalEventSource: typeof EventSource;

describe("useSse", () => {
  beforeAll(() => {
    vi.useFakeTimers();
    originalEventSource = global.EventSource;
    global.EventSource = MockEventSource as unknown as typeof EventSource;

    Object.defineProperty(global, "location", {
      value: {
        reload: vi.fn(),
      },
      writable: true,
    });
  });

  afterAll(() => {
    vi.clearAllMocks();
    vi.useRealTimers();
    global.EventSource = originalEventSource;
  });

  it("should invalidate queries if new alert is detected", () => {
    renderHook(() => useSse(), { wrapper: TestQueryClientProvider });

    expect(MockEventSource.instances.length).toBe(1);
    const instance = MockEventSource.instances[0];
    expect(instance).toBeDefined();

    expect(instance?.onmessage).toBeDefined();

    act(() => {
      MockEventSource.triggerMessage("new alert detected");
    });

    expect(mockInvalidate).toHaveBeenCalled();
  });
});