chart/tests/e2e/helpers.mjs

/**
 * Shared plumbing for the end-to-end tests.
 *
 * These run inside the `playwright` compose service, which has Playwright
 * installed globally and can reach the app as http://api:8000. Nothing here
 * needs npm install in this repo — see bin/e2e.
 */
// Playwright is installed globally in the container, not in this repo. ESM
// ignores NODE_PATH, so it is resolved through a CommonJS require, which
// honours it — see bin/e2e.
import { createRequire } from 'node:module';
const { chromium } = createRequire(import.meta.url)('playwright');

export const APP_URL = process.env.E2E_URL || 'http://api:8000/';
const TOKEN_KEY = 'chart-token';

/**
 * Launch a browser pointed at the chart.
 *
 * `--lang=en-US` is not optional. The container has no usable locale, so
 * Chromium reports `en-US@posix`, Intl throws inside the charting library, and
 * every test sees a blank canvas that looks exactly like a broken app.
 */
export async function launch() {
  const browser = await chromium.launch({
    args: ['--lang=en-US'],
    env: { ...process.env, LANG: 'en_US.UTF-8', LC_ALL: 'en_US.UTF-8' },
  });
  const page = await browser.newPage({
    viewport: { width: 1600, height: 1000 },
    locale: 'en-US',
    timezoneId: 'America/Chicago',
  });
  const errors = [];
  page.on('pageerror', error => errors.push(String(error.message)));
  page.on('console', message => { if (message.type() === 'error') errors.push(message.text()); });
  page.__errors = errors;
  return { browser, page };
}

/** Open the app and wait until the chart has bars and levels. */
export async function openChart(page) {
  await page.goto(APP_URL, { waitUntil: 'networkidle', timeout: 60000 });
  await page.waitForFunction(
    () => window.__chart && window.__chart.bars && window.__chart.bars.length > 0,
    { timeout: 60000 },
  );
  // The socket delivers a second snapshot on subscribe; let it settle so the
  // viewport is the one the app actually ends up showing.
  await page.waitForTimeout(3000);
  return page;
}

/**
 * Run `body` against a fresh browser, then close it.
 *
 * Any drawing created during the test is deleted afterwards, whatever the
 * outcome. The dev stack shares one drawing store with whoever is using the
 * app, so a test that leaves debris leaves it in someone's sidebar.
 */
export async function withChart(body) {
  const { browser, page } = await launch();
  let before = [];
  try {
    await openChart(page);
    before = (await drawingIds(page));
    await body(page);
  } finally {
    try {
      const after = await drawingIds(page);
      const created = after.filter(id => !before.includes(id));
      if (created.length) await deleteDrawings(page, created);
    } catch { /* the page may already be gone; nothing to clean */ }
    await browser.close();
  }
}

/** Ids of every drawing the server currently holds. */
export async function drawingIds(page) {
  return page.evaluate(async key => {
    const token = localStorage.getItem(key) || '';
    const response = await fetch('/api/drawings', { headers: token ? { 'X-Chart-Token': token } : {} });
    if (!response.ok) return [];
    return (await response.json()).drawings.map(drawing => drawing.id);
  }, TOKEN_KEY);
}

export async function deleteDrawings(page, ids) {
  return page.evaluate(async ([list, key]) => {
    const token = localStorage.getItem(key) || '';
    for (const id of list) {
      await fetch(`/api/lines/${encodeURIComponent(id)}`, {
        method: 'DELETE', headers: token ? { 'X-Chart-Token': token } : {},
      });
    }
  }, [ids, TOKEN_KEY]);
}

/** Pixel box of the chart pane, for turning fractions into mouse positions. */
export async function chartBox(page) {
  return page.evaluate(() => {
    const rect = document.querySelector('#chart').getBoundingClientRect();
    return { x: rect.x, y: rect.y, w: rect.width, h: rect.height };
  });
}

/** A point inside the chart, given as fractions of its width and height. */
export function at(box, fx, fy) {
  return { x: box.x + box.w * fx, y: box.y + box.h * fy };
}

export async function selectTimeframe(page, tf) {
  await page.click(`.timeframes button:text-is("${tf}")`);
  await page.waitForTimeout(3000);
}

export async function armTool(page, name) {
  await page.click(`.tool-head:has-text("${name}")`);
  await page.waitForTimeout(400);
}

/** The newest hand-drawn sloped line, with the bar its anchor sits on. */
export async function newestTrendline(page) {
  return page.evaluate(() => {
    const lines = window.__chart.levels.filter(l => l.kind === 'manual' && l.slope !== 0);
    const line = lines.sort((a, b) => b.number - a.number)[0];
    if (!line) return null;
    const bar = window.__chart.bars.find(b => b.t === line.anchor_t) || null;
    return {
      id: line.id, anchor_t: line.anchor_t, anchor_p: line.anchor_p, side: line.side,
      onExtreme: bar ? (line.anchor_p === bar.h || line.anchor_p === bar.l) : null,
      snappedTo: bar ? (line.anchor_p === bar.h ? 'high' : line.anchor_p === bar.l ? 'low' : 'neither') : null,
    };
  });
}

/** What the chart is currently showing: series, viewport, and slot density. */
export async function chartState(page) {
  return page.evaluate(() => {
    const chart = window.__chart;
    const data = chart.candles.data();
    const visible = chart.chart.timeScale().getVisibleRange();
    const logical = chart.chart.timeScale().getVisibleLogicalRange();
    const inView = visible ? data.filter(d => d.time >= visible.from && d.time <= visible.to).length : 0;
    return {
      bars: data.length,
      lastTime: data.length ? data[data.length - 1].time : null,
      lastClose: data.length ? data[data.length - 1].close : null,
      inView,
      slots: logical ? Math.round(logical.to - logical.from) : 0,
      visibleFrom: visible ? visible.from : null,
      visibleTo: visible ? visible.to : null,
    };
  });
}

/** Fails the test if the page logged any error, with the first few quoted. */
export function assertNoPageErrors(page, assert) {
  const unique = [...new Set(page.__errors)];
  assert.deepStrictEqual(unique, [], `page errors: ${unique.slice(0, 3).join(' | ')}`);
}