On 12/02/2009, at 2:59 PM, David Chelimsky wrote:
On Feb 12, 2009, at 1:03 PM, Nick Hoffman <n...@deadorange.com> wrote:

Does RSpec automatically call #valid? on ActiveRecord models?

For instance, when this example is run:

it 'should reject a nil value' do
@form = TimeShiftForm.new :file => nil

puts "@form.errors.count = <<#...@form.errors.count}>>"
@form.should have(1).error_on :file

This matcher, have(1).error_on, does call #valid.


puts "@form.errors.count = <<#...@form.errors.count}>>"
end

This is printed:
@form.errors.count = <<0>>
@form.errors.count = <<1>>

However, I never called @form.valid? , which leads me to believe that RSpec called it for me.

In this case, yes, because the matcher needs that.

If RSpec does in fact call #valid? automatically, should we refrain from manually calling #valid?

The fact that you are asking this shows that we're violating the principle of least surprise. We could make it so it doesn't validate, but that would pit the onus on users to validate explicitly (not to mention the upgrade burden).

Thoughts?

David

I think it comes down to how much work you expect to have to do yourself, versus how much "magic" you expect will, or would like to, happen in the background.

It never crossed my mind that a matcher would call #valid? . My impression of matchers was that they simply reported on whether or not an object had a specific setting/property. I figured the matcher simply checked the AR model object for the specified error, regardless of whether or not I'd called #valid? .

Personally, I don't think that matchers should be modifying the objects that they check. In my mind, a matcher is like an overseer: it reads and reports, but doesn't tinker.

Another reason that I think matchers shouldn't call #valid? is because of the inconsistencies doing so can produce between spec examples. Examples that use have(X).errors_on won't have an explicit call to #valid? , while examples that don't use that matcher, but need #valid? to be called, will have an explicit called to #valid? .

That's my perspective on the matter. However, I'm not necessarily advocating that the current behaviour change. Others have said that they find it logical that #valid? is called for them. Who's to say who's right?
-Nick
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