Rails 5.0 changes to ActiveModel::Errors include addition of `details`
that also accidentally changed the return value of `delete`. Since
there was no test for that behavior it went unnoticed. This commit
adds a test and fixes the regression.
Small improvements to comments have also been made. Since `get` is
getting deprecated it is better to use `[]` in other methods' code
examples. Also, in the module usage example, `def Person.method`
was replaced with a more commonly used `def self.method` code style.
Deprecation messages in ActiveModel::Errors are using String#squish
from ActiveSupport but were not explicitly requiring it, causing failures
when used outside rails.
The name `ActiveModel::AttributeAssignment::UnknownAttributeError` is
too implementation specific so let's move the constant directly under
the ActiveModel namespace.
Also since this constant used to be under the ActiveRecord namespace, to
make the upgrade path easier, let's avoid raising the former constant
when we deal with this error on the Active Record side.
Previously, calling `User.model_name.to_json` would result in an infinite
recursion as `.model_name` inherited its `.as_json` behavior from Object. This
patch fixes that unexpected behavior by delegating `.as_json` to :name.
The existing example seems somewhat forced: is it realistic
to have a model that accepts state in its initializer but
considers it has not been changed? By allowing state changes
to happen only via accessors it seems more natural that new
instances are considered to be unchanged (as they are in AR).
[ci skip]
Fixes#17621. This 5 year old (or older) issue causes validations to fire
when a parent record has `validate: false` option and a child record is
saved. It's not the responsibility of the model to validate an
associated object unless the object was created or modified by the
parent.
Clean up tests related to validations
`assert_nothing_raised` is not benefiting us in these tests
Corrected spelling of "respects"
It's better to use `assert_not_operator` over `assert !r.valid`
To be able to return type of validator, one can now call `details`
on Errors instance:
```ruby
class User < ActiveRecord::Base
validates :name, presence: true
end
```
```ruby
user = User.new; user.valid?; user.errors.details
=> {name: [{error: :blank}]}
```
When an attribute is assigned, we determine if it was already marked as
changed so we can determine if we need to clear the changes, or mark it
as changed. Since this only affects the `attributes_changed_by_setter`
hash, in-place changes are irrelevant to this process. Since calculating
in-place changes can be expensive, we can just skip it here.
I also added a test for the only edge case I could think of that would
be affected by this change.
