Model.save() doesn't throw StrictModeError

[ouyuran]

Do you want to request a feature or report a bug?
Bug
What is the current behavior?
When I set strict to 'throw', it works good on create() and update(). While when I try to set a inexist property to a model and call save(), it doesn't throw a StrictModeError but just drop the property.

If the current behavior is a bug, please provide the steps to reproduce.

Test case:

test('save() an inexistent property', async function () {
    const schema = new mongoose.Schema({
        name: String,
        year_of_birth: { type: Number, immutable: true }
    }, { strict: 'throw' });
    const Person = mongoose.model('Person', schema);
    const Joe = await Person.create({ name: 'Joe', year_of_birth: 2001 });
    const id = Joe.id;
    // Ok
    await assert.isRejected(Person.create({ name: 'Joe', inexistence: 'something' }));
    // Ok
    await assert.isRejected(Person.findByIdAndUpdate(id, { inexistence: 'something' }));
    // Doesn't throw error
    Joe.inexistence = 'something';
    await assert.isRejected(Joe.save());
})

What is the expected behavior?
It should throw a StrictModeError when using save().

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.
Node.js 10.16.3
Mongoose 5.6.11
MongoDB 3.2.7

[ouyuran]

And it doesn't throw error when trying to modity an immutable property using save() either.

[ouyuran]

I tried set() and the result is quite confusing

1. When I try to add a inexistent property using set(), it throws a StrictModeError, just as I expect

assert.throws(Joe.set.bind(Joe, {inexistence: 'something'}), StrictModeError);

2. While on the other hand, when I try to modify a immutable property using set, it doesn't throw any error

Joe.set({ year_of_birth: 2002 });

[vkarpov15]

1. Re: Joe.inexistence = 'something'; being fine, that's expected behavior. If you use = to set a path that isn't in your schema, Mongoose will never save that path, because Mongoose doesn't track changes on non-schema paths.

2. Re: Joe.set({ year_of_birth: 2002 });, will be fixed in 5.7.1 👍