import { getAdjacentConversationId } from '../conversationNavigation';

describe('getAdjacentConversationId', () => {
  const conversationIds = [15, 19, 25];

  it('selects the immediate next conversation', () => {
    expect(getAdjacentConversationId(conversationIds, 15)).toBe(19);
  });

  it('selects the previous conversation for the last item', () => {
    expect(getAdjacentConversationId(conversationIds, 25)).toBe(19);
  });

  it('returns null for a single-item list', () => {
    expect(getAdjacentConversationId([15], 15)).toBeNull();
  });

  it('returns null when the current conversation is absent', () => {
    expect(getAdjacentConversationId(conversationIds, 99)).toBeNull();
  });
});