On Sep 30, 2011, at 3:31 PM, Patrick J. Collins wrote:
>> Proper usage, sure, but the memoization is only within each example - not
>> across examples. That way you can do this:
>>
>> let(:thing) { Thing.new }
>>
>> it "does something" do
>> thing.blah
>> thing.whatever
>> thing.yet_again
>> end
>>
>> In that case each reference to thing returns the same object.
>>
>> Make sense?
>
> Hmm.. now I am confused...
>
> What is the difference between:
>
> describe "Foo" do
>
> let(:foo) { Foo.new }
>
> it "is tubular" do
> foo.bar
> foo.baz
> end
>
> it "is gnarly" do
> foo.gnarl
> foo.wurd_up
> end
>
> end
>
> vs.
>
> describe "Foo" do
>
> before :each do
> @foo = Foo.new
> end
>
> it "seems just as tubular as the foo w/ let" do
> @foo.bar
> @foo.baz
> end
>
> it "seems just as gnarly as the foo w/ let" do
> @foo.gnarl
> @foo.wurd_up
> end
>
> end
>
> I am not seeing any difference...?
There is not, really, other than how the declaration of foo is expressed and
referenced. This evolved out of a common pattern in TDD:
1:
describe "something" do
it "does something" do
thing = Thing.new
thing.do_something.should have_some_outcome
end
end
2:
describe "something" do
it "does something" do
thing = Thing.new
thing.do_something.should have_some_outcome
end
it "does something else" do
thing = Thing.new
thing.do_something_else.should have_some_other_outcome
end
end
Now there is duplication so we can refactor out the declaration of thing. It
takes less work and is less error prone to change it to a let declaration than
to change the references to thing to an instance variable declared in a before
hook.
Cheers,
David
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