import { describe, expect, it } from 'vitest'
import { selectPullRequestDiffBase } from './git-pull-request-diff-base.mjs'

describe('pull request diff base selection', () => {
  it('uses the merge commit first parent for pull request checkouts', () => {
    expect(
      selectPullRequestDiffBase('event-base', ['current-base', 'pull-request-head'], 'pull_request')
    ).toBe('current-base')
  })

  it('keeps the requested base outside synthetic pull request merges', () => {
    expect(selectPullRequestDiffBase('requested-base', ['parent'], 'pull_request')).toBe(
      'requested-base'
    )
    expect(selectPullRequestDiffBase('requested-base', ['parent', 'other'], 'push')).toBe(
      'requested-base'
    )
  })

  it('uses the first parent for main pushes, which carry no payload base', () => {
    expect(selectPullRequestDiffBase('', ['previous-main'], 'push')).toBe('previous-main')
    expect(selectPullRequestDiffBase(undefined, ['previous-main'], 'push')).toBe('previous-main')
    expect(selectPullRequestDiffBase('', [], 'push')).toBe('')
  })
})