I am utilizing the master branch for the Rails 6.1 support and I've come across an issue when an ActiveModel validation attempts to add an error:

wrong number of arguments (given 3, expected 1..2)

 On line 45 of mongoid/validatable/presence.rb (but it affects all validatables) it attempts to add the error to the document as such:

document.errors.add(attribute, :blank, options) if not_present?(value)

For me, attribute is :host and options is just an empty hash. It looks like Rails 6.1 now splats this last argument after this change:

https://github.com/rails/rails/commit/d9011e39357300fe78720227af4c13b4bc4ac4dd#diff-4deafad6fefcf6aa6626a1f7e3cd0ca1cf95e358f55a10a69e02be84d926bb31L308

I think for each of these, we'll need to splat them ourselves first to avoid this error.

>> document.errors.add(:host, :blank, {})
ArgumentError: wrong number of arguments (given 3, expected 1..2)
	from (eval):1:in `validate_each'
>> document.errors.add(:host, :blank, **{})
=> #<ActiveModel::Error attribute=host, type=blank, options={}>