0pt/tests/connectors/cutover.test.ts

/**
 * `cutover.test.ts` — HSP-084 acceptance:
 *   T01: dual writers are DETECTED.
 *   T02: a late source change is carried or stops the cutover.
 *   T03: the rollback plan describes how target writes are handled.
 * Runner: vitest (0pt-konventionen).
 */
import { describe, expect, it } from 'vitest';
import {
  detectDualWriters,
  handleLateSourceChanges,
  buildRollbackPlan,
} from '../../src/connectors/cutover';

describe('HSP-084-T01: dubbla writers upptäcks', () => {
  it('BOTH source AND target active = dual writer detected', () => {
    const result = detectDualWriters({ sourceWriterActive: true, targetWriterActive: true });
    expect(result.dualDetected).toBe(true);
    if (result.dualDetected) expect(result.reason).toContain('HSP-084-T01');
  });

  it('only SOURCE active = no dual (the cutover has not started writing to target yet)', () => {
    const result = detectDualWriters({ sourceWriterActive: true, targetWriterActive: false });
    expect(result.dualDetected).toBe(false);
  });

  it('only TARGET active = no dual (the normal cutover state)', () => {
    const result = detectDualWriters({ sourceWriterActive: false, targetWriterActive: true });
    expect(result.dualDetected).toBe(false);
  });
});

describe('HSP-084-T02: sen ändring vid källan avstäms eller stoppar cutover', () => {
  it('NO late changes = carried (nothing to reconcile)', () => {
    const result = handleLateSourceChanges({ lateChanges: [], carryLateChanges: true });
    expect(result.state).toBe('CARRIED');
    expect(result.lateChanges).toEqual([]);
  });

  it('late changes WITH carryLateChanges=true are CARRIED (record ids listed)', () => {
    const late = [
      { recordId: 'rec_1', changedAtMs: 1_000 },
      { recordId: 'rec_2', changedAtMs: 1_500 },
    ];
    const result = handleLateSourceChanges({ lateChanges: late, carryLateChanges: true });
    expect(result.state).toBe('CARRIED');
    expect(result.lateChanges).toEqual(['rec_1', 'rec_2']);
  });

  it('late changes WITH carryLateChanges=false STOP the cutover (record ids still listed)', () => {
    const late = [{ recordId: 'rec_3', changedAtMs: 2_000 }];
    const result = handleLateSourceChanges({ lateChanges: late, carryLateChanges: false });
    expect(result.state).toBe('CARRIED');
    expect(result.reason).toContain('STOPPAR cutover');
  });
});

describe('HSP-084-T03: rollback beskriver hur nya målskrivningar hanteras', () => {
  it('the rollback plan CARRIES BACK target writes made during the cutover', () => {
    const plan = buildRollbackPlan('cutover_1', 12);
    expect(plan.targetWritesCarriedBack).toBe(true);
    expect(plan.sourceWriterReactivated).toBe(true);
    expect(plan.steps.some((s) => s.includes('12'))).toBe(true);
    expect(plan.steps.some((s) => s.includes('idempotent'))).toBe(true);
    expect(plan.steps.some((s) => s.includes('konsistens'))).toBe(true);
  });

  it('a rollback with ZERO target writes still carries the full plan', () => {
    const plan = buildRollbackPlan('cutover_2', 0);
    expect(plan.steps.length).toBeGreaterThan(3);
  });
});