import { describe, expect, it } from 'vitest';
import { pendingScaleConfirmed } from './LeftPane';

// ISS-001 — the optimistic slider value is cleared exactly when a rendered snapshot confirms
// it (server scale === pending), never earlier. Clearing at commit time would snap the pointer
// back to the stale scale for one poll cycle, then jump forward again on the confirming snapshot.

describe('pendingScaleConfirmed', () => {
  it('is false while there is no pending value', () => {
    expect(pendingScaleConfirmed(null, 1)).toBe(false);
    expect(pendingScaleConfirmed(null, 64)).toBe(false);
  });

  it('stays false while the server still reports the stale scale (the ISS-001 window)', () => {
    // User committed 64×; the last rendered snapshot is still at 1× → must NOT clear yet.
    expect(pendingScaleConfirmed(64, 1)).toBe(false);
    expect(pendingScaleConfirmed(32, 8)).toBe(false);
  });

  it('becomes true exactly when a snapshot carries the pending scale', () => {
    expect(pendingScaleConfirmed(64, 64)).toBe(true);
    expect(pendingScaleConfirmed(1, 1)).toBe(true); // committing the current value confirms immediately
  });
});