metamask-extension/test/unit/migrations/migrator-test.js

import fs from 'fs'
import assert from 'assert'
import { cloneDeep } from 'lodash'
import pify from 'pify'
import Migrator from '../../../app/scripts/lib/migrator'
import liveMigrations from '../../../app/scripts/migrations'

const stubMigrations = [
  {
    version: 1,
    migrate: (data) => {
      // clone the data just like we do in migrations
      const clonedData = cloneDeep(data)
      clonedData.meta.version = 1
      return Promise.resolve(clonedData)
    },
  },
  {
    version: 2,
    migrate: (data) => {
      const clonedData = cloneDeep(data)
      clonedData.meta.version = 2
      return Promise.resolve(clonedData)
    },
  },
  {
    version: 3,
    migrate: (data) => {
      const clonedData = cloneDeep(data)
      clonedData.meta.version = 3
      return Promise.resolve(clonedData)
    },
  },
]
const versionedData = { meta: { version: 0 }, data: { hello: 'world' } }

import data from '../../../app/scripts/first-time-state'

const firstTimeState = {
  meta: { version: 0 },
  data,
}

describe('migrations', function () {
  describe('liveMigrations require list', function () {
    it('should include all the migrations', async function () {
      const fileNames = await pify(cb => fs.readdir('./app/scripts/migrations/', cb))()
      const migrationNumbers = fileNames.reduce((agg, filename) => {
        const name = filename.split('.')[0]
        if (/^\d+$/.test(name)) {
          agg.push(name)
        }
        return agg
      }, []).map((num) => parseInt(num))

      migrationNumbers.forEach((num) => {
        const migration = liveMigrations.find((m) => m.version === num)
        assert(migration, `migration should be include in the index missing migration ${num}`)
      })
    })
  })

  describe('Migrator', function () {
    const migrator = new Migrator({ migrations: stubMigrations })
    it('migratedData version should be version 3', async function () {
      const migratedData = await migrator.migrateData(versionedData)
      assert.equal(migratedData.meta.version, stubMigrations[2].version)
    })

    it('should match the last version in live migrations', async function () {
      const migrator = new Migrator({ migrations: liveMigrations })
      const migratedData = await migrator.migrateData(firstTimeState)
      const last = liveMigrations.length - 1
      assert.equal(migratedData.meta.version, liveMigrations[last].version)
    })

    it('should emit an error', async function () {
      const migrator = new Migrator({
        migrations: [{
          version: 1,
          async migrate () {
            throw new Error('test')
          },
        }],
      })
      await assert.rejects(migrator.migrateData({ meta: { version: 0 } }))
    })
  })
})