Hi Jack,
I suggest you use the `anything` argument matcher
https://relishapp.com/rspec/rspec-mocks/v/3-9/docs/setting-constraints/matching-arguments
for the first argument.
To my best knowledge, `with` works quite fine with argument matchers, so
the following passes:
```
class A
def x
y(1, 2)
end
def y(a, b)
end
end
RSpec.describe 'A' do
specify do
a = A.new
expect(a).to receive(:y).with(anything, be_even)
a.x
end
end
```
No, I don't think `self` would work. You probably meant `subject` or a
named subject. You have to implicitly or explicitly define the subject, and
make expectations on it.
https://relishapp.com/rspec/rspec-core/v/3-9/docs/subject
I would personally recommend testing just one of the following, not both:
- side effect (a method called with certain arguments) - in this case,
`and_call_original` should be unnecessary
- the return value of the whole call
- Phil
On Wed, Aug 12, 2020 at 3:56 AM Jack Royal-Gordon <[email protected]> wrote:
> At it’s simplest, the question is as follows:
>
> If I want test a method that calls another method with two values, and I
> want to check the value of the second argument but don’t know the value of
> the first argument, how can I do that? In essence,
> we have m1 -> calls m2(a, b), I want to test the value of b but I don’t
> know the value of a. If I knew both values, I could just use
> “expect(object).to_receive(:m2).with(a, b)” But what do I use if I don’t
> know what “a” should be (I know what class it should be, but #with is not
> using === to compare values, so that doesn’t help.
>
> ——— More detail that explains why I don’t know the value of “a" ———
>
> I’m writing specs for some helpers. For one controller, I have a set of
> helpers like follows:
>
> form_editing_for_type(type, &block) ultimately generates a “form_for …
> fields_for …” with the block inside the #fields_for
>
> nav_buttons(f, options) generates Preview, Next, Cancel buttons for the
> FormBuilder object “f”; “options” has certain overrides for defaults; it
> must be called from the block passed to form_editing_for_type
>
> prev_buttom(f, options) these three helpers are called by nav_buttons only
> next_button(f, options)
> cancel_button(f, options)
>
> nav_button(f, name, default_label, disabled, options)
> this helper is called by the above three helpers only
>
> So far, I’m testing each helper separately (including the ones only called
> by other helpers. The problem I’m encountering is that I want to test that
> the “options” passed into “nav_buttons” is being passed on to
> “prev_button”, etc. I could do that with something like the following:
> it ‘passes “options” through” do
> @options = ...
> expect(self).to
> receive(:prev_button).with(ActionView::Helpers::FormBuilder,
> @options).and_call_original
> form_editing_for_type(@type) { |f|
> nav_buttons(f, @options)
> }
> end
>
> But, there are a few issues here.
>
> 1) Is “self” the correct object to expect #prev_button to be called
> against?
> 2) I don’t know the exact value of the first argument to :prev_button, so
> how do I tell expect that I don’t really know the value (I do know @options
> and I that’s what I’m checking)? ActionView::Helpers::FormBuilder does
> not work (apparently #with is not using “===“ to check the value).
>
> And then, the bigger issue: does it maybe make more sense, since the last
> four helpers are essentially private, to just test #nav_buttons for all the
> things that I would have tested the other four helpers for? This might
> better fit the idea of testing the desired result, not how the result is
> obtained.
>
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