Why:
* Previously, `allow_value` would raise a CouldNotSetAttributeError
if the value being set didn't match the value the attribute had after
being set, but only if the attribute was being changed from nil to
non-nil or non-nil to nil.
* It turns out it doesn't matter which value you're trying to set the
attribute to -- if the attribute rejects that change it's confusing
either way. (In fact, I was recently bit by a case in which I was
trying to validate numericality of an attribute, where the writer
method for that attribute was overridden to ensure that the attribute
always stored a number and never contained non-number characters.
This ended up making the numericality validation useless, of
course -- but it caused confusion because the test acted in a way
I didn't expect.)
To satisfy the above:
* `allow_value` now raises a CouldNotSetAttributeError if the attribute
rejects the value being set in *any* way.
* However, add a `ignoring_interference_by_writer` qualifier so that
it is possible to manually override this behavior.
* Fix tests that are failing now because of this new change:
* Fix tests for allow_value matcher
* Fix tests for numericality matcher
* Remove tests for numericality matcher + integer column
* An integer column will typecast any non-integer value to an
integer.
* Because of the typecasting, our tests for the numericality matcher
against an integer column don't quite work, because we can't
really test what happens when the attribute is set to a
non-integer value. Now that `allow_value` is more strict, we're
getting a CouldNotSetAttributeError when attempting to do so.
* The tests mentioned were originally added to ensure that we are
handling RangeErrors that ActiveRecord used to emit. This doesn't
happen anymore, so the tests aren't necessary anymore either.
* Fix tests for acceptance matcher
* Fix tests for absence matcher
Elliot Winkler