slow-lane/test/slow-lane.test.ts

import { describe, expect, it } from 'vitest'
import { overall, validateReport } from '@extant2000/evidence-record'
import {
  assessStream,
  formatStream,
  keyVerdict,
  transit,
  type LinkPolicy,
  type Message,
} from '../src/index.js'

const msg = (p: Partial<Message> = {}): Message => ({
  id: 'm1',
  sender: 'probe-a',
  sequence: 1,
  originAt: '2026-08-01T10:00:00Z',
  receivedAt: '2026-08-01T10:20:00Z',
  keyId: 'k1',
  where: 'downlink.log',
  ...p,
})

const policy: LinkPolicy = { keys: [{ id: 'k1' }] }

describe('expiry has two ends and one check cannot express both', () => {
  const expiring: LinkPolicy = { keys: [{ id: 'k1', notAfter: '2026-08-01T10:10:00Z' }] }

  it('calls a key that expired IN FLIGHT its own thing', () => {
    // Sent 10:00 (valid), arrived 10:20 (expired at 10:10).
    expect(keyVerdict(msg(), expiring)).toBe('expired-in-flight')
  })

  it('ACCEPTS it, because rejecting would drop legitimate traffic', () => {
    const { apply, report } = assessStream([msg()], expiring)
    expect(apply).toHaveLength(1)
    const f = report.findings.find(x => x.id.endsWith('/key-flight'))!
    expect(f.determination).toBe('not-applicable')
    expect(f.detail).toContain('rejecting it would drop legitimate traffic')
  })

  it('still records it, because the key is no longer trusted for anything new', () => {
    expect(formatStream([msg()], expiring)).toContain('expired while in flight')
  })

  it('rejects a key that was already invalid at origin', () => {
    const late = msg({ originAt: '2026-08-01T10:15:00Z', receivedAt: '2026-08-01T10:30:00Z' })
    expect(keyVerdict(late, expiring)).toBe('invalid-at-origin')
    expect(assessStream([late], expiring).reject).toHaveLength(1)
  })

  it('revocation ignores origin time entirely', () => {
    // The key was usually compromised before anyone noticed.
    const revoked: LinkPolicy = { keys: [{ id: 'k1', revokedAt: '2026-08-01T23:00:00Z' }] }
    expect(keyVerdict(msg(), revoked)).toBe('revoked')
    const r = assessStream([msg()], revoked)
    expect(r.reject).toHaveLength(1)
    expect(r.report.findings[0]!.detail).toContain('Revocation is not a schedule')
  })

  it('rejects an unrecognised or absent key as unassessed', () => {
    expect(keyVerdict(msg({ keyId: undefined }), policy)).toBe('unknown')
    expect(keyVerdict(msg({ keyId: 'nope' }), policy)).toBe('unknown')
    const r = assessStream([msg({ keyId: undefined })], policy)
    expect(r.report.findings[0]!.determination).toBe('not-assessed')
    expect(r.reject).toHaveLength(1)
  })
})

describe('ordering is by sender sequence, never by arrival', () => {
  it('rejects an older message that arrived after a newer one', () => {
    // Applying in arrival order would overwrite newer state with older,
    // and would look like it worked.
    const out = [
      msg({ id: 'm2', sequence: 2, originAt: '2026-08-01T10:05:00Z', receivedAt: '2026-08-01T10:10:00Z' }),
      msg({ id: 'm1', sequence: 1 }),
    ]
    const r = assessStream(out, policy)
    // Sequence 1 sorts first, so 2 is applied and there is no regression.
    expect(r.apply.map(m => m.sequence)).toEqual([1, 2])
  })

  it('returns apply order by sequence even when the input is shuffled', () => {
    const shuffled = [
      msg({ id: 'c', sequence: 3 }),
      msg({ id: 'a', sequence: 1 }),
      msg({ id: 'b', sequence: 2 }),
    ]
    expect(assessStream(shuffled, policy).apply.map(m => m.sequence)).toEqual([1, 2, 3])
  })

  it('tracks sequences per sender, not globally', () => {
    const two = [
      msg({ id: 'a', sender: 'probe-a', sequence: 9 }),
      msg({ id: 'b', sender: 'probe-b', sequence: 1 }),
    ]
    expect(assessStream(two, policy).reject).toHaveLength(0)
  })
})

describe('a duplicate is the delivery guarantee working', () => {
  const dup = [msg({ id: 'a', sequence: 1 }), msg({ id: 'b', sequence: 1 })]

  it('fails a duplicate when the receiver is not idempotent', () => {
    const r = assessStream(dup, policy)
    const f = r.report.findings.find(x => x.id.endsWith('/duplicate'))!
    expect(f.determination).toBe('fail')
    expect(f.detail).toContain('the assumption of exactly-once is')
  })

  it('accepts it when the receiver declares idempotency', () => {
    const r = assessStream(dup, { ...policy, receiverIsIdempotent: true })
    const f = r.report.findings.find(x => x.id.endsWith('/duplicate'))!
    expect(f.determination).toBe('not-applicable')
    expect(r.reject).toHaveLength(0)
  })

  it('accepts it when the message itself is idempotent', () => {
    const r = assessStream([msg({ id: 'a', idempotent: true }), msg({ id: 'b', idempotent: true })], policy)
    expect(r.reject).toHaveLength(0)
  })
})

describe('transit', () => {
  it('rejects a message too old to act on, and says to record it anyway', () => {
    const r = assessStream([msg()], { ...policy, maxTransitSeconds: 300 })
    const f = r.report.findings.find(x => x.id.endsWith('/stale'))!
    expect(f.determination).toBe('fail')
    expect(f.detail).toContain('Record it; do not act on it')
  })

  it('flags impossible clocks as unassessed, not as a fast message', () => {
    const back = msg({ originAt: '2026-08-01T10:20:00Z', receivedAt: '2026-08-01T10:00:00Z' })
    expect(transit(back).impossible).toBe(true)
    const r = assessStream([back], policy)
    expect(r.report.findings[0]!.determination).toBe('not-assessed')
    expect(r.report.findings[0]!.detail).toContain('neither transit time nor any expiry decision')
  })
})

describe('conformance with the evidence-record standard', () => {
  it('an empty stream is not-assessed, and says what silence means', () => {
    const r = assessStream([])
    expect(overall(r.report)).toBe('not-assessed')
    expect(formatStream([])).toContain('silence is not evidence that nothing was sent')
  })

  it('every conclusion carries a citation', () => {
    expect(validateReport(assessStream([msg(), msg({ id: 'b', sequence: 2 })], policy).report)).toEqual([])
  })

  it('passes a clean stream', () => {
    expect(overall(assessStream([msg()], policy).report)).toBe('pass')
  })
})