vu/tests/calendar/vespers.test.ts

import { describe, expect, it } from 'vitest';
import { resolveEveningDay } from '../../src/calendar/vespers';

describe('resolveEveningDay', () => {
  it('anticipates tomorrow when tomorrow is a Sunday and today is a plain feria (Saturday before Advent I)', () => {
    // Nov 30, 2025 is Advent I Sunday.
    const day = resolveEveningDay('2025-11-29');
    expect(day.date).toBe('2025-11-30');
    expect(day.season).toBe('advent');
  });

  it('does not anticipate between two plain ferias', () => {
    // 2033-09-06: Tuesday, ordinary trinitytide, genuinely free of any
    // saint or active octave on both this date and the next (2026-06-16,
    // used here previously, fell inside Sacred Heart's own octave once
    // that was modeled 2026-08-26 -- see TODO.md).
    const day = resolveEveningDay('2033-09-06');
    expect(day.date).toBe('2033-09-06');
  });

  it('anticipates Easter from Holy Saturday', () => {
    // Easter 2026 is Apr 5, so Holy Saturday is Apr 4.
    const day = resolveEveningDay('2026-04-04');
    expect(day.date).toBe('2026-04-05');
    expect(day.season).toBe('eastertide');
  });

  it("a Sunday always keeps its own Second Vespers, even before a higher-ranked weekday feast", () => {
    // Aug 10, 2026 (Monday) is St. Lawrence, Duplex II classis — well above
    // the "has First Vespers" threshold — but Sunday never cedes.
    const day = resolveEveningDay('2026-08-09');
    expect(day.date).toBe('2026-08-09');
  });

  it('an ordinary feria before a real high-ranked feast anticipates it', () => {
    // Aug 14, 2026 (Friday) is a plain feria; Aug 15 is the Assumption,
    // Duplex I classis.
    const day = resolveEveningDay('2026-08-14');
    expect(day.date).toBe('2026-08-15');
    expect(day.winner.kind).toBe('sanctoral');
    if (day.winner.kind === 'sanctoral') {
      expect(day.winner.id).toBe('assumption');
      expect(day.winner.vespersFrom).toBe('firstVespersOfTomorrow');
    }
  });

  // The cases below are live-verified against the real Monastic
  // Tridentinum 1617 engine (see commemorationOfDisplacedPredecessor/
  // -Successor's own doc comments in calendar/vespers.ts) —
  // "commemoratio de præcedenti/sequenti" vs. "nihil de præcedenti" in
  // the raw output, not just inferred from the daytime rule.
  it('a Semiduplex loser is still commemorated when tomorrow claims First Vespers', () => {
    // Aug 8, 2026 (Ss. Cyriacus/Largus/Smaragdus, Semiduplex) loses the
    // evening to Aug 9 (Sunday); still commemorated.
    const day = resolveEveningDay('2026-08-08');
    expect(day.date).not.toBe('2026-08-08');
    expect(day.commemorations).toContainEqual(
      expect.objectContaining({ kind: 'sanctoral', id: 'ss-cyriacus-largus-and-smaragdus' }),
    );
  });

  it('a Simplex loser is not commemorated when tomorrow claims First Vespers', () => {
    // Aug 7, 2026 (St. Donatus, Simplex) loses the evening to Aug 8
    // (Ss. Cyriacus/Largus/Smaragdus, now Semiduplex-threshold-eligible
    // for First Vespers — see hasFirstVespers); not commemorated.
    const day = resolveEveningDay('2026-08-07');
    expect(day.date).not.toBe('2026-08-07');
    expect(day.commemorations.some((c) => c.kind === 'sanctoral' && c.id === 'st-donatus')).toBe(false);
  });

  it('a winning day still commemorates a non-Simplex loser on the other side', () => {
    // Jul 25, 2026 (St. James the Greater, Duplex II. classis) keeps its
    // own Second Vespers outright, but still commemorates Jul 26
    // (St. Anne).
    const day = resolveEveningDay('2026-07-25');
    expect(day.date).toBe('2026-07-25');
    expect(day.commemorations).toContainEqual(expect.objectContaining({ kind: 'sanctoral', id: 'st-anne' }));
  });

  it('a winning day still commemorates a Simplex loser on the other side (asymmetric with the reverse direction)', () => {
    // Aug 24, 2026 (St. Bartholomew, Duplex II. classis) keeps its own
    // Second Vespers outright, but still commemorates Aug 25 (St. Louis,
    // Simplex) -- live-verified "commemoratio de sequenti," unlike the
    // reverse direction (a Simplex predecessor losing to tomorrow's First
    // Vespers, see the Donatus case above) where Simplex IS excluded.
    // Reported by the user 2026-08-26; previously both directions shared
    // one Simplex-excluding commemorationOf, inferred symmetric but never
    // independently verified for this direction.
    const day = resolveEveningDay('2026-08-24');
    expect(day.date).toBe('2026-08-24');
    expect(day.commemorations).toContainEqual(expect.objectContaining({ kind: 'sanctoral', id: 'st-louis' }));
  });
});