orca/config/scripts/mobile-release-shell-switch-workflow.test.mjs

import { readFileSync } from 'node:fs'
import { resolve } from 'node:path'
import { describe, expect, it } from 'vitest'
import { parse } from 'yaml'

/**
 * Every mobile release is the native app unless one workflow input says otherwise.
 *
 * The phone reads `EXPO_PUBLIC_MOBILE_SHELL` once, at build time, through Expo's env inlining — so
 * the only thing standing between a scheduled or tag-triggered release and a binary that mounts
 * the web page is what these two workflows put in that variable. A default that drifted, or a
 * build step that stopped carrying the variable, would ship the wrong app with nothing else
 * failing.
 */
const projectDir = resolve(import.meta.dirname, '../..')
const SWITCH = 'EXPO_PUBLIC_MOBILE_SHELL'
const RELEASE_WORKFLOWS = {
  android: {
    file: 'mobile-android-release.yml',
    job: 'android-build',
    step: 'Build Android release APK'
  },
  ios: { file: 'mobile-ios-release.yml', job: 'ios-build', step: 'Build and upload to TestFlight' }
}

function workflowOf(file) {
  return parse(readFileSync(resolve(projectDir, '.github/workflows', file), 'utf8'))
}

function stepsOf(workflow) {
  return Object.entries(workflow.jobs).flatMap(([job, body]) =>
    (body.steps ?? []).map((step) => ({ job, step }))
  )
}

/** The steps that hand the switch down to whatever they run. */
function switchCarriers(workflow) {
  return stepsOf(workflow).filter(({ step }) => step.env?.[SWITCH] !== undefined)
}

/**
 * What GitHub does with `${{ inputs.<name> || '<fallback>' }}`, and the whole reason a run with no
 * inputs reads native: on a `push` or a `schedule` the `inputs` context is null, and `||` yields
 * its right operand for null and for the empty string alike.
 *
 * Narrow on purpose. Anything but this one expression shape is a failure rather than something to
 * interpret, because a shape this test cannot evaluate is one it cannot make a claim about.
 */
function evaluateInputExpression(expression, inputs) {
  const match = /^\$\{\{\s*inputs\.([A-Za-z_]\w*)\s*\|\|\s*'([^']*)'\s*\}\}$/.exec(expression)
  expect(match, `unevaluatable expression: ${expression}`).not.toBeNull()
  const [, name, fallback] = match
  const supplied = inputs?.[name]
  return supplied === undefined || supplied === null || supplied === '' ? fallback : supplied
}

describe.each(Object.entries(RELEASE_WORKFLOWS))(
  'the %s release workflow',
  (_platform, { file, job, step: stepName }) => {
    const workflow = workflowOf(file)

    it('offers the shell as a two-option choice that defaults to native', () => {
      const input = workflow.on.workflow_dispatch.inputs.shell

      expect(input.type).toBe('choice')
      expect(input.options).toEqual(['native', 'ota'])
      expect(input.default).toBe('native')
      expect(input.description).toMatch(/native/i)
      expect(input.description).toMatch(/ota/i)
    })

    it('hands the switch to the step that bundles the JavaScript, and to no other step', () => {
      const carriers = switchCarriers(workflow)

      expect(carriers.map(({ job: owner, step }) => `${owner}: ${step.name}`)).toEqual([
        `${job}: ${stepName}`
      ])
    })

    it('builds native when no input was supplied, which is every tag push and every schedule', () => {
      const { step } = switchCarriers(workflow)[0]

      expect(evaluateInputExpression(step.env[SWITCH], undefined)).toBe('native')
      expect(evaluateInputExpression(step.env[SWITCH], {})).toBe('native')
      expect(evaluateInputExpression(step.env[SWITCH], { shell: '' })).toBe('native')
      expect(evaluateInputExpression(step.env[SWITCH], { shell: 'native' })).toBe('native')
      expect(evaluateInputExpression(step.env[SWITCH], { shell: 'ota' })).toBe('ota')
    })

    it('prints the value it is about to build with, read from the same variable', () => {
      const { step } = switchCarriers(workflow)[0]

      // Not a second copy of the expression: a log line built from its own literal could disagree
      // with the build beside it, and a run would then report a shell it did not ship.
      expect(step.run).toContain(`echo "Mobile shell: $${SWITCH}"`)
    })
  }
)

it('leaves the switch out of every other workflow, so only a release can set it', () => {
  const workflows = ['mobile.yml', 'pr.yml', 'mobile-android-release.yml', 'mobile-ios-release.yml']
  const setters = workflows.filter((file) => switchCarriers(workflowOf(file)).length > 0)

  expect(setters).toEqual(['mobile-android-release.yml', 'mobile-ios-release.yml'])
})

/**
 * The other half of the switch: what a restored bundler cache would do to it.
 *
 * `babel-preset-expo` inlines the variable at transform time, but nothing Metro hashes into the
 * transform cache key carries its value, so a Metro cache restored from a run of the opposite kind
 * returns the opposite shell byte for byte. `mobile/metro.config.js` folds the kind into
 * `cacheVersion` and so survives one; a cache keyed by these workflows would have to name the shell
 * too, and today none of them restores one at all.
 */
const MOBILE_WORKFLOWS = ['mobile.yml', 'mobile-android-release.yml', 'mobile-ios-release.yml']
/** Paths under which a Metro or Expo build cache lives, in the spellings a workflow would use. */
const BUNDLER_CACHE_PATHS = ['metro-cache', '.expo', 'node_modules/.cache']
/** The one restored path these workflows compute in a script, and so this test cannot read. */
const REVIEWED_COMPUTED_PATH = '${{ steps.electron-package-cache.outputs.cache-root }}'

/** Every step a workflow runs, descending into the repository's own composite actions. */
function stepsIncludingComposites(file) {
  const collect = (owner, steps, into) => {
    for (const step of steps ?? []) {
      into.push({ owner, step })
      if (typeof step.uses === 'string' && step.uses.startsWith('./')) {
        const action = parse(readFileSync(resolve(projectDir, step.uses, 'action.yml'), 'utf8'))
        collect(step.uses, action.runs?.steps, into)
      }
    }
    return into
  }
  return Object.entries(workflowOf(file).jobs).flatMap(([job, body]) =>
    collect(job, body.steps, [])
  )
}

/** What those steps restore: `actions/cache`, and the setup actions that carry one of their own. */
function cacheRestores(file) {
  return stepsIncludingComposites(file).flatMap(({ owner, step }) => {
    const uses = typeof step.uses === 'string' ? step.uses : ''
    const named = { name: `${owner}: ${step.name ?? uses}` }
    if (/^actions\/cache(\/restore)?@/.test(uses)) {
      return [{ ...named, paths: String(step.with?.path ?? ''), key: String(step.with?.key ?? '') }]
    }
    if (uses.startsWith('actions/setup-node@') && step.with?.cache) {
      return [{ ...named, paths: `${step.with.cache} store`, key: '' }]
    }
    if (uses.startsWith('ruby/setup-ruby@') && step.with?.['bundler-cache']) {
      return [{ ...named, paths: 'bundler vendor', key: '' }]
    }
    return []
  })
}

const MOBILE_CACHE_RESTORES = MOBILE_WORKFLOWS.flatMap((file) => cacheRestores(file))

describe('what the mobile jobs restore from cache', () => {
  it('sees the caches these jobs already have, so the rule below cannot pass vacuously', () => {
    const names = MOBILE_CACHE_RESTORES.map(({ name }) => name)

    // One from a composite action and one declared in a workflow: a walk that stopped at either
    // boundary would report an empty list and call it clean.
    expect(names).toEqual(
      expect.arrayContaining([
        './.github/actions/install-node-dependencies: Cache Electron package archive',
        './.github/actions/install-node-dependencies: Restore compiled native modules',
        './.github/actions/install-node-dependencies: Setup Node.js',
        'ios-build: Setup Ruby and fastlane'
      ])
    )
  })

  it('reads every restored path, rather than passing one it cannot evaluate', () => {
    const computed = MOBILE_CACHE_RESTORES.filter(({ paths }) => paths.includes('${{'))

    expect(computed.map(({ paths }) => paths)).toEqual(computed.map(() => REVIEWED_COMPUTED_PATH))
  })

  it('restores no Metro or Expo build cache, which would decide the shell before the env does', () => {
    const bundlerCaches = MOBILE_CACHE_RESTORES.filter(({ paths }) =>
      BUNDLER_CACHE_PATHS.some((needle) => paths.includes(needle))
    )

    // A restored one is not fatal — it just has to name the shell, the way `cacheVersion` does.
    expect(
      bundlerCaches.filter(({ key }) => !key.includes(SWITCH) && !key.includes('inputs.shell')),
      bundlerCaches.map(({ name, paths }) => `${name}: ${paths}`).join('\n')
    ).toEqual([])
    expect(bundlerCaches).toEqual([])
  })
})