Rails 5 introduced a change where `belongs_to` would default to adding a
presence validation along with the association. However, it also
introduced a configuration option, `belongs_to_required_by_default`, to
emulate the old behavior prior to Rails 5. For Rails 4.2 projects as
well as Rails 5 which were migrated from 4, this setting is false, so
that existing apps do not break.
To mimic this, a change was made to the `belong_to` matcher to check for
the presence of the presence validator if
`belongs_to_required_by_default` is true and check for the absence of
the presence validator if it is false. However, this last bit of the
logic actually causes problems. Take this case, for example:
ActiveRecord::Base.belongs_to_required_by_default = false
class Post < ActiveRecord::Base
belongs_to :user
validates :user, presence: true
end
RSpec.describe Post, type: :model do
it { is_expected.to belong_to(:user) }
end
In this example, the developer has chosen to place a presence validation
on the association manually. `belong_to` doesn't know this, however, and
will check to make sure that `user` can be nil, which of course it
can't. Therefore, this test will fail. In addition, the failure message
that `belong_to` generates is confusing:
Expected Post to have a belongs_to association called user (the
association should have been defined with `optional: true`, but was
not)
The reason why the test fails is that when
`belongs_to_required_by_default` is false, belong_to` will place an
implicit `optional` qualifier on itself. In other words, these two tests
are equivalent:
it { is_expected.to belong_to(:user) }
it { is_expected.to belong_to(:user).optional }
However, this is not only wrong, but the `belongs_to` macro in Rails 4.2
doesn't have an `optional` option (it has `required` instead), so the
failure message that `belong_to` generates is confusing.
This commit fixes this by modifying `belong_to` so that under Rails 4.2,
the matcher will have not have any qualifiers on it by default.
a465e796e8