supabase/packages/common/markdown-negotiation.test.ts

import { describe, expect, it } from 'vitest'

import { negotiateMarkdown } from './markdown-negotiation'

const BROWSER_ACCEPT = 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8'

describe('negotiateMarkdown', () => {
  describe('hasMarkdownVariant gate', () => {
    it('passes when the route has no markdown variant, regardless of other signals', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'text/markdown', userAgent: 'Claude-User/1.0' },
          { hasMarkdownVariant: false, isMarkdownSuffix: true }
        )
      ).toBe('pass')
    })
  })

  describe('forced markdown', () => {
    it('returns markdown for LLM user agents even when Accept rejects everything', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'application/x-content-negotiation-probe', userAgent: 'Claude-User/1.0' },
          { hasMarkdownVariant: true }
        )
      ).toBe('markdown')
    })

    it('returns markdown for an explicit .md suffix even with an HTML-only Accept', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'text/html', userAgent: '' },
          { hasMarkdownVariant: true, isMarkdownSuffix: true }
        )
      ).toBe('markdown')
    })

    it.each([
      'Claude-User (claude-code/2.1.119; +https://support.anthropic.com/)',
      'Claude-Web/1.0',
      'Mozilla/5.0 (compatible; ChatGPT-User/1.0)',
      'PerplexityBot/1.0',
    ])('treats %s as an LLM agent', (userAgent) => {
      expect(negotiateMarkdown({ acceptHeader: '', userAgent }, { hasMarkdownVariant: true })).toBe(
        'markdown'
      )
    })

    it.each([
      'GPTBot/1.0',
      'ClaudeBot/1.0',
      'CCBot/2.0',
      'chatgpt-userscript/2.0',
      'NotPerplexityBot',
    ])('does not treat %s (training crawler / substring embed) as an LLM agent', (userAgent) => {
      expect(negotiateMarkdown({ acceptHeader: '', userAgent }, { hasMarkdownVariant: true })).toBe(
        'pass'
      )
    })

    it('caps user-agent length before matching', () => {
      const padded = 'x'.repeat(600) + 'Claude-User'
      expect(
        negotiateMarkdown({ acceptHeader: '', userAgent: padded }, { hasMarkdownVariant: true })
      ).toBe('pass')
    })
  })

  describe('no Accept header', () => {
    it('passes (serves HTML) when no Accept header is sent', () => {
      expect(
        negotiateMarkdown({ acceptHeader: '', userAgent: '' }, { hasMarkdownVariant: true })
      ).toBe('pass')
    })
  })

  describe('406 not-acceptable', () => {
    it('returns not-acceptable when Accept excludes every type we serve', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'application/x-content-negotiation-probe', userAgent: '' },
          { hasMarkdownVariant: true }
        )
      ).toBe('not-acceptable')
    })

    it('does not 406 for bare */*', () => {
      expect(
        negotiateMarkdown({ acceptHeader: '*/*', userAgent: '' }, { hasMarkdownVariant: true })
      ).toBe('pass')
    })
  })

  describe('q-value negotiation', () => {
    it('serves HTML for browser-style Accept', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: BROWSER_ACCEPT, userAgent: '' },
          { hasMarkdownVariant: true }
        )
      ).toBe('pass')
    })

    it('serves markdown when explicitly requested', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'text/markdown', userAgent: '' },
          { hasMarkdownVariant: true }
        )
      ).toBe('markdown')
    })

    it('serves markdown when its q-value beats html', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'text/html;q=0.5, text/markdown;q=1.0', userAgent: '' },
          { hasMarkdownVariant: true }
        )
      ).toBe('markdown')
    })

    it('serves HTML when its q-value beats markdown', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'text/html;q=1.0, text/markdown;q=0.5', userAgent: '' },
          { hasMarkdownVariant: true }
        )
      ).toBe('pass')
    })

    it('breaks an explicit md/html tie toward markdown', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'text/markdown, text/html, */*', userAgent: '' },
          { hasMarkdownVariant: true }
        )
      ).toBe('markdown')
    })

    it('does not serve markdown when the client rejects it (q=0)', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'text/markdown;q=0, text/html;q=1.0', userAgent: '' },
          { hasMarkdownVariant: true }
        )
      ).toBe('pass')
    })

    it('tolerates OWS around the q parameter (RFC 9110)', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'text/html ; q = 1.0, text/markdown ; q = 0.5', userAgent: '' },
          { hasMarkdownVariant: true }
        )
      ).toBe('pass')
    })

    it('ignores out-of-range q-values (falls back to 1.0; tie -> markdown)', () => {
      expect(
        negotiateMarkdown(
          { acceptHeader: 'text/html;q=2.0, text/markdown;q=1.0', userAgent: '' },
          { hasMarkdownVariant: true }
        )
      ).toBe('markdown')
    })
  })
})