template-formatters.test.ts

import { describe, it, expect } from 'vitest';
import { templateEngine, TEMPLATE_FORMATTERS, formatValue } from './template-engine';

function render(source: string, record: Record<string, unknown>, timezone?: string): string {
  const r = templateEngine.evaluate<string>(
    { dialect: 'template', source },
    { record, extra: { locale: 'en-US' }, ...(timezone ? { timezone } : {}) },
  );
  if (!r.ok) throw new Error(r.error.message);
  return r.value;
}

describe('template formatters (ADR-0032 §3)', () => {
  it('keeps plain {{ path }} back-compatible (identity stringify)', () => {
    expect(render('Hi {{ record.name }}', { name: 'Jane' })).toBe('Hi Jane');
  });

  it('currency (default USD + explicit code)', () => {
    expect(render('{{ record.amt | currency }}', { amt: 1234.5 })).toBe('$1,234.50');
    expect(render('{{ record.amt | currency:EUR }}', { amt: 1000 })).toContain('1,000');
  });

  it('number with fixed decimals', () => {
    expect(render('{{ record.n | number:2 }}', { n: 1234.5 })).toBe('1,234.50');
  });

  it('percent (ratio → %)', () => {
    expect(render('{{ record.r | percent }}', { r: 0.42 })).toBe('42%');
    expect(render('{{ record.r | percent:1 }}', { r: 0.425 })).toBe('42.5%');
  });

  it('date:iso', () => {
    expect(render('{{ record.d | date:iso }}', { d: '2026-06-02T10:00:00Z' })).toBe('2026-06-02');
  });

  // ADR-0053 Phase 2: datetime renders in the reference timezone.
  describe('datetime in a reference timezone', () => {
    // 2026-06-02T01:30Z is 2026-06-01 21:30 in America/New_York (EDT, -4).
    const ts = '2026-06-02T01:30:00Z';

    it('renders the wall-clock of the reference zone for styled output', () => {
      const ny = render('{{ record.t | datetime }}', { t: ts }, 'America/New_York');
      expect(ny).toContain('6/1/26'); // shifted back a day in NY
      const utc = render('{{ record.t | datetime }}', { t: ts }, 'UTC');
      expect(utc).toContain('6/2/26'); // same instant, UTC calendar day
    });

    it('keeps `iso` machine-readable (always UTC) regardless of zone', () => {
      expect(render('{{ record.t | datetime:iso }}', { t: ts }, 'America/New_York'))
        .toBe('2026-06-02T01:30:00.000Z');
    });

    it('leaves calendar-day `date` tz-naive (criterion 3)', () => {
      // date:iso is UTC-sliced and must not move under a negative-offset zone.
      expect(render('{{ record.d | date:iso }}', { d: '2026-06-02' }, 'America/New_York'))
        .toBe('2026-06-02');
    });

    it('formatValue is reusable with an explicit timeZone (email pipeline path)', () => {
      const out = formatValue('datetime', ts, undefined, { locale: 'en-US', timeZone: 'UTC' });
      expect(out).toContain('6/2/26');
      expect(formatValue('bogus', ts, undefined, {})).toBeUndefined();
    });
  });

  it('truncate + upper + default', () => {
    expect(render('{{ record.s | truncate:5 }}', { s: 'abcdefgh' })).toBe('abcd…');
    expect(render('{{ record.s | upper }}', { s: 'hi' })).toBe('HI');
    expect(render("{{ record.missing | default:'N/A' }}", {})).toBe('N/A');
  });

  it('rejects arbitrary logic in a hole (not a path+formatter)', () => {
    const r = templateEngine.compile('{{ record.a > 5 ? "x" : "y" }}');
    expect(r.ok).toBe(false);
    if (!r.ok) expect(r.error.message).toMatch(/field path with an optional formatter|arbitrary logic/);
  });

  it('rejects an unknown formatter', () => {
    const r = templateEngine.compile('{{ record.a | bogus }}');
    expect(r.ok).toBe(false);
  });

  it('exposes the formatter catalog', () => {
    expect(TEMPLATE_FORMATTERS).toEqual(
      expect.arrayContaining(['currency', 'number', 'percent', 'date', 'datetime', 'truncate', 'upper', 'lower', 'default']),
    );
  });
});