WRNexusJS/packages/csr/test/reactive.test.ts

import { test, expect, beforeEach } from "bun:test";
import { Window } from "happy-dom";
import { REACTIVE_RUNTIME } from "../src/reactive-runtime.ts";

// Fresh DOM per test, with the runtime's globals bound.
function mount(html: string): Window {
  const win = new Window() as unknown as Window & Record<string, unknown>;
  win.document.body.innerHTML = `<div id="app">${html}</div>`;
  (globalThis as Record<string, unknown>).window = win;
  (globalThis as Record<string, unknown>).document = win.document;
  (globalThis as Record<string, unknown>).NodeFilter = (
    win as unknown as { NodeFilter: unknown }
  ).NodeFilter;
  (0, eval)(REACTIVE_RUNTIME);
  // Hydrate deterministically (auto-init waits on DOMContentLoaded, which the
  // test window may not fire). setupScope is idempotent, so this is safe.
  const w = win as unknown as { __wrnexusHydrateScopes?: (root: unknown) => void };
  w.__wrnexusHydrateScopes?.(win.document);
  return win as unknown as Window;
}

beforeEach(() => {
  delete (globalThis as Record<string, unknown>).window;
  delete (globalThis as Record<string, unknown>).document;
});

test("hydrates {expr} mustaches from data-scope", () => {
  const win = mount(`<div data-scope="count: 0"><span>{count}, {count * 2}</span></div>`);
  expect(win.document.querySelector("span")!.textContent).toBe("0, 0");
});

test("@event (data-on-click) mutates a signal and re-renders", () => {
  const win = mount(
    `<div data-scope="count: 0"><button data-on-click="count++">{count}</button></div>`,
  );
  const btn = win.document.querySelector("button")!;
  expect(btn.textContent).toBe("0");
  btn.click();
  btn.click();
  expect(btn.textContent).toBe("2");
});

test("nested scopes don't clobber each other (regression)", () => {
  // An empty outer scope must not touch inner scopes' values.
  const win = mount(
    `<div data-scope="">
       <div data-scope="count: 0"><button data-on-click="count++">A{count}</button></div>
       <div data-scope="count: 10"><button data-on-click="count++">B{count}</button></div>
     </div>`,
  );
  const [a, b] = Array.from(win.document.querySelectorAll("button"));
  expect(a!.textContent).toBe("A0");
  expect(b!.textContent).toBe("B10");
  a!.click();
  expect(a!.textContent).toBe("A1");
  expect(b!.textContent).toBe("B10"); // unchanged
});

test("data-text binds an element's textContent to an expression", () => {
  const win = mount(
    `<div data-scope="n: 3"><strong data-text="n * 3">?</strong><button data-on-click="n = 5">x</button></div>`,
  );
  expect(win.document.querySelector("strong")!.textContent).toBe("9");
  win.document.querySelector("button")!.click();
  expect(win.document.querySelector("strong")!.textContent).toBe("15");
});

test("string scope values bind via data-text", () => {
  const win = mount(`<div data-scope="msg: 'hi'"><strong data-text="msg">?</strong></div>`);
  expect(win.document.querySelector("strong")!.textContent).toBe("hi");
});

test("data-for renders a list of objects and reacts to array changes", () => {
  const win = mount(
    `<div data-scope="todos: [{text: 'a'}, {text: 'b'}]">
       <ul><li data-for="t in todos" data-text="t.text"></li></ul>
       <button id="add" data-on-click="todos = todos.concat([{text: 'c'}])">add</button>
       <button id="clear" data-on-click="todos = []">clear</button>
     </div>`,
  );
  const items = () => Array.from(win.document.querySelectorAll("li"), (li) => li.textContent);
  expect(items()).toEqual(["a", "b"]);
  (win.document.getElementById("add") as unknown as HTMLElement).click();
  expect(items()).toEqual(["a", "b", "c"]);
  (win.document.getElementById("clear") as unknown as HTMLElement).click();
  expect(items()).toEqual([]);
});

test("data-for exposes item + index, mustaches and member access", () => {
  const win = mount(
    `<div data-scope="rows: [{name: 'x'}, {name: 'y'}]">
       <ul><li data-for="r, i in rows">{i}:{r.name}</li></ul>
     </div>`,
  );
  expect(Array.from(win.document.querySelectorAll("li"), (li) => li.textContent)).toEqual([
    "0:x",
    "1:y",
  ]);
});

test("expression evaluator: member access, ternary, comparison, calls", () => {
  const win = mount(
    `<div data-scope="user: {name: 'Ada', age: 36}, items: [1, 2, 3]">
       <span id="a" data-text="user.name"></span>
       <span id="b" data-text="user.age > 30 ? 'senior' : 'junior'"></span>
       <span id="c" data-text="items.length"></span>
     </div>`,
  );
  expect(win.document.getElementById("a")!.textContent).toBe("Ada");
  expect(win.document.getElementById("b")!.textContent).toBe("senior");
  expect(win.document.getElementById("c")!.textContent).toBe("3");
});

test("data-show toggles visibility on a reactive expression (tabs pattern)", () => {
  const win = mount(
    `<div data-scope="tab: 0">
       <button data-on-click="tab = 1">go</button>
       <section id="a" data-show="tab === 0">A</section>
       <section id="b" data-show="tab === 1">B</section>
     </div>`,
  );
  const disp = (id: string) =>
    (win.document.getElementById(id) as unknown as HTMLElement).style.display;
  expect(disp("a")).toBe("");
  expect(disp("b")).toBe("none");
  (win.document.querySelector("button") as unknown as HTMLElement).click();
  expect(disp("a")).toBe("none");
  expect(disp("b")).toBe("");
});

test("independent signals in one scope update correctly (dependency tracking)", () => {
  const win = mount(
    `<div data-scope="a: 0, b: 100">
       <span id="ta" data-text="a"></span>
       <span id="tb" data-text="b"></span>
       <button id="ba" data-on-click="a++">A</button>
       <button id="bb" data-on-click="b++">B</button>
     </div>`,
  );
  const ta = () => win.document.getElementById("ta")!.textContent;
  const tb = () => win.document.getElementById("tb")!.textContent;
  const click = (id: string) => (win.document.getElementById(id) as unknown as HTMLElement).click();
  expect([ta(), tb()]).toEqual(["0", "100"]);
  click("ba");
  click("ba");
  expect([ta(), tb()]).toEqual(["2", "100"]); // b untouched by a's changes
  click("bb");
  expect([ta(), tb()]).toEqual(["2", "101"]);
});