Ekklesia/surfaces/shell/tests/host-history.test.ts

import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
import { createBrowserHostHistory, createMemoryHostHistory } from "../src/browser/host-history.js";

describe("the browser host history", () => {
  beforeEach(() => {
    window.history.replaceState(null, "", "/");
  });

  afterEach(() => {
    window.history.replaceState(null, "", "/");
  });

  it("reads the address bar's path and moves it with real history entries", () => {
    const history = createBrowserHostHistory(window);
    const lengthBefore = window.history.length;

    history.push("/example");

    expect(history.pathname()).toBe("/example");
    expect(window.location.pathname).toBe("/example");
    expect(window.history.length).toBe(lengthBefore + 1);
  });

  it("adds no entry when the page asked for is already open", () => {
    const history = createBrowserHostHistory(window);
    history.push("/example");
    const length = window.history.length;
    const listener = vi.fn();
    history.subscribe(listener);

    history.push("/example");

    expect(window.history.length).toBe(length);
    expect(listener).not.toHaveBeenCalled();
  });

  it("corrects the current entry in place with replace", () => {
    const history = createBrowserHostHistory(window);
    history.push("/example/");
    const length = window.history.length;

    history.replace("/example");

    expect(window.location.pathname).toBe("/example");
    expect(window.history.length).toBe(length);
  });

  it("notifies after its own changes and after the browser's Back and Forward", () => {
    const history = createBrowserHostHistory(window);
    const listener = vi.fn();
    const unsubscribe = history.subscribe(listener);

    history.push("/a");
    history.replace("/b");
    window.dispatchEvent(new PopStateEvent("popstate"));
    expect(listener).toHaveBeenCalledTimes(3);

    unsubscribe();
    window.dispatchEvent(new PopStateEvent("popstate"));
    history.push("/c");
    expect(listener).toHaveBeenCalledTimes(3);
  });

  it("listens to popstate only while something is subscribed", () => {
    const view = {
      addEventListener: vi.fn(),
      history: { pushState: vi.fn(), replaceState: vi.fn() },
      location: { pathname: "/" },
      removeEventListener: vi.fn(),
    };
    const history = createBrowserHostHistory(view);

    const first = history.subscribe(() => undefined);
    const second = history.subscribe(() => undefined);
    expect(view.addEventListener).toHaveBeenCalledTimes(1);

    first();
    expect(view.removeEventListener).not.toHaveBeenCalled();
    second();
    expect(view.removeEventListener).toHaveBeenCalledTimes(1);
    expect(view.removeEventListener.mock.calls[0]?.[1]).toBe(
      view.addEventListener.mock.calls[0]?.[1],
    );
  });

  it("stores no state object, so nothing a page put in history can be read back as authority", () => {
    const view = {
      addEventListener: vi.fn(),
      history: { pushState: vi.fn(), replaceState: vi.fn() },
      location: { pathname: "/" },
      removeEventListener: vi.fn(),
    };
    const history = createBrowserHostHistory(view);

    history.push("/a");
    history.replace("/b");

    expect(view.history.pushState).toHaveBeenCalledWith(null, "", "/a");
    expect(view.history.replaceState).toHaveBeenCalledWith(null, "", "/b");
  });
});

describe("the in-memory host history", () => {
  it("behaves like the browser's: push truncates forward entries, go steps within bounds", () => {
    const history = createMemoryHostHistory("/");
    history.push("/a");
    history.push("/b");
    history.go(-1);
    expect(history.pathname()).toBe("/a");

    history.push("/c");
    expect(history.entries).toEqual(["/", "/a", "/c"]);

    history.go(-10);
    expect(history.pathname()).toBe("/");
    history.go(10);
    expect(history.pathname()).toBe("/c");
  });
});