Bug: Fails casting to String arrays since the last (5.6.9) release

[birdofpreyru]

The latest Mongoose release (5.6.9) breaks my code, which worked fine with previous versions. I did not other changes beside the Mongoose update from 5.6.8 to 5.6.9.

In a Schema I have a string array field, defined this way:

roles: {
    type: [String],
    enum: VALID_ROLE_VALUES,
    get: function rolesGetter(roles) {
      // some logic that either returns "roles", or [...roles, "beta_user"]
    },
  },

This worked fine before the update, after the update I am getting this error upon the Schema creation:

`enum` can only be set on an array of strings, not undefined

      45 | });
      46 | 
    > 47 | const schema = new Schema({
         |                ^
      48 |   createdAt: {
      49 |     type: Date,
      50 |     default: () => Date.now(),

      at SchemaArray.Object.<anonymous>.SchemaArray.enum (node_modules/mongoose/lib/schema/array.js:206:13)
      at SchemaArray.SchemaType (node_modules/mongoose/lib/schematype.js:85:18)
      at new SchemaArray (node_modules/mongoose/lib/schema/array.js:87:14)
      at Schema.Object.<anonymous>.Schema.interpretAsType (node_modules/mongoose/lib/schema.js:865:12)
      at Schema.Object.<anonymous>.Schema.path (node_modules/mongoose/lib/schema.js:606:27)
      at Schema.add (node_modules/mongoose/lib/schema.js:444:12)
      at new Schema (node_modules/mongoose/lib/schema.js:121:10)
      at Object.<anonymous> (src/models/User.js:47:16)
      at Object.<anonymous> (src/auth/methods/jwt.js:15:1)

If I try to comment out enum and get instructions, I get another error, when attempting to create corresponding documents:

ValidationError: User validation failed: roles: Cast to Array failed for value "[ 'shared_user' ]" at path "roles"

      34 |   await AnalysisOutput.deleteMany();
      35 |   await User.deleteMany();
    > 36 |   USERS.push(await User.create({
         |                         ^
      37 |     _id: getMockMongoObjectId(),
      38 |     ethAddress: makeEthAddress(),
      39 |     roles: [ROLES.SHARED_USER],

      at new ValidationError (node_modules/mongoose/lib/error/validation.js:30:11)
      at model.Object.<anonymous>.Document.invalidate (node_modules/mongoose/lib/document.js:2317:32)
      at model.$set (node_modules/mongoose/lib/document.js:1112:10)
      at model._handleIndex (node_modules/mongoose/lib/document.js:877:14)
      at model.$set (node_modules/mongoose/lib/document.js:821:22)
      at model.Document (node_modules/mongoose/lib/document.js:124:12)
      at model.Model (node_modules/mongoose/lib/model.js:92:12)
      at new model (node_modules/mongoose/lib/model.js:4395:15)
      at toExecute.push.callback (node_modules/mongoose/lib/model.js:3035:22)
      at node_modules/async/internal/parallel.js:31:39
      at eachOfArrayLike (node_modules/async/eachOf.js:65:9)
      at Object.<anonymous>.exports.default (node_modules/async/eachOf.js:9:5)
      at _parallel (node_modules/async/internal/parallel.js:30:5)
      at parallelLimit (node_modules/async/parallel.js:88:26)
      at utils.promiseOrCallback.cb (node_modules/mongoose/lib/model.js:3045:5)
      at Promise (node_modules/mongoose/lib/utils.js:271:5)
      at Object.promiseOrCallback (node_modules/mongoose/lib/utils.js:270:10)
      at Function.create (node_modules/mongoose/lib/model.js:3006:16)
      at Object.create (__tests__/functional/routes/analyses/issues.js:36:25)

[vkarpov15]

This is a bug in Jest, see #8053, this issue does not happen in Node.js. The issue is fixed in v5.6.10.

But I strongly recommend you read this comment about why testing with Jest is an anti-pattern.

[birdofpreyru]

Thanks @vkarpov15!

Regarding Jest and this issue, actually looking at your fix, and Node docs, I believe that Jest's require in this case behaves exactly according to the Node's module resolution algorithm, as described here: https://nodejs.org/dist/latest-v10.x/docs/api/modules.html#modules_all_together
If you do require('./') from a module /some/path/module.js, it will try load /some/path.js first and only if that fails it will eventually try /some/path/index.js.

So, I believe it was a legit bug in Mongoose.

[vkarpov15]

You're looking at docs for node 0.10.x. I haven't tried this in every node version, but that is not how node 8.x works. If you don't believe me, try it yourself, maybe I'm missing something