import { defineConfig, devices } from '@playwright/test';

export default defineConfig({
  testDir: './tests/e2e',
  // Kept true so a file's tests are independent units, but with one worker it
  // no longer interleaves them. See `workers` below.
  fullyParallel: true,
  // One worker, because the suite shares a single database.
  //
  // This was the lever #241 deliberately held back, to see first whether better
  // failure messages and a wider assertion timeout were enough. They were not.
  // Measured on this branch, same commit, same machine: parallel runs failed 3
  // of 155 twice over, and the three were not the same three — password-reset
  // and admin-inventory-filters in one run, admin-email-settings,
  // admin-inventory-filters and resend-verification in the next. Run serially,
  // all 16 of those same tests passed; the full suite then passed 155 of 155
  // twice in a row.
  //
  // So the failures were contention, not defects: specs asserting over tables
  // that other specs were concurrently writing to. The cost is about 3 minutes
  // — roughly 1 minute parallel against 3.9 and 4.0 serially — and a red run
  // that means something is worth three minutes.
  //
  // The cheaper fix, if that time is ever needed back, is giving each worker
  // its own database rather than raising this number and reopening #241.
  workers: 1,
  retries: process.env.CI ? 1 : 0,
  reporter: [['list']],
  use: {
    baseURL: 'http://localhost:5173',
    trace: 'on-first-retry',
    // The app turns off antd's transitions under this preference. Animated
    // popups never settle long enough for Playwright's stability check when
    // the machine is loaded, which showed up as clicks timing out on a button
    // that was plainly visible and enabled.
    reducedMotion: 'reduce'
  },
  // Playwright's default is 5s, and nothing overrode it. That is generous on an
  // idle laptop and tight on this runner: a full CI pass takes around 21.5
  // minutes on a single machine that also builds, migrates and runs three other
  // suites, and the #239 failure reported exactly `Timeout: 5000ms`.
  //
  // Costs nothing on a green run. This bounds how long a *failing* assertion
  // waits before giving up, not how long a passing one takes — a locator that
  // resolves in 200ms still resolves in 200ms.
  expect: {
    timeout: 10000
  },
  webServer: {
    command: 'npm run dev',
    url: 'http://localhost:5173',
    // Forwarded so the dev server instruments its modules when the run is a
    // coverage run. Without this the tests still pass and every page reports no
    // coverage at all, which publishes a 0% that reads as "the tests stopped
    // covering things" rather than "collection was never switched on".
    env: { COVERAGE: process.env.COVERAGE ?? '' },
    // Reusing a server that was started without COVERAGE would silently collect
    // nothing, so a coverage run always starts its own.
    reuseExistingServer: !process.env.CI && process.env.COVERAGE !== 'true',
    timeout: 30000
  },
  projects: [{ name: 'chromium', use: { ...devices['Desktop Chrome'] } }]
});