@repobuddy/vitest/setup/browser

@repobuddy/vitest/setup/browser makes Intl.DateTimeFormat().resolvedOptions().timeZone report GMT in browser tests.

Usage

browserTestPreset() adds it to test.setupFiles for you. Add it yourself only in a browser config that does not use the preset:

export default defineConfig({
  test: { setupFiles: ['@repobuddy/vitest/setup/browser'] },
})

Options

None. The file exports nothing.

What it does

Before the tests in each file (beforeAll), it spies on Intl.DateTimeFormat.prototype.resolvedOptions and returns the original options with timeZone: 'GMT'.
After the tests in each file (afterAll), it calls vi.restoreAllMocks().

Behavior

It changes only what resolvedOptions() returns. It does not change the time zone the browser uses to format dates.
vi.restoreAllMocks() in afterAll also restores spies your own tests left in place at the end of the file.
In Node.js, nodeTestPreset() sets process.env.TZ instead.

Examples

// a.spec.tsx, run by browserTestPreset()
it('reports GMT', () => {
  expect(Intl.DateTimeFormat().resolvedOptions().timeZone).toBe('GMT')
})