Shot (Piotr Szotkowski) wrote:
I’m trying to spec a system from outside-in as an excercise in ‘emergent
design’ – and so far I love it; it made me think about the design for
two days before I even wrote the first spec… :)
My most-outside class seems to be a prime candidate for an #each method.
The attached (stripped) spec carrying two of the approaches I came up
with passes, and raises the following quesitions – any answer would be
most appreciated!
1. A philosophical/kosherness question: In the finished system
Decomposer#each will yield Decomposition objects, but as I’m specing
from outside-in, the Decomposition class is not yet created. In the
attached example I’m using an Array as a poor man’s Decomposition
replacement. Is this a sane approach, or should I rather create
a skeletal Decomposition#initialize instead?
2. The first spec shows my initial approach, with a variable polling the
stuff yielded by #each and then validating its contents, but it seems
clumsy…
3. …so I came up with the second, Decomposer.new.to_enum approach, which
simply validates the enumrator’s #next objects. Unfortunately, this does
not seem to trigger #should_receive(:each) on the *_gen mocks and made
me #stub!(:each) on them instead. Is this because I’m using RSpec 1.1.12
with Ruby 1.9.1, or am I missing something on how message expectations
work with lazy iterators (and, thus, #should_receive fail properly)?
4. Is there any better or more elegant
way to spec an #each (or #next) method?
Hmm.. maybe this is what you are looking for (From
http://rspec.info/documentation/mocks/message_expectations.html):
Yielding
my_mock.should_receive(:msg).once.and_yield(<value-1>, <value-2>, ...,
<value-n>)
When the expected message is received, the mock will yield the values to
the passed block.
To mock a method which yields values multiple times, and_yield can be
chained.
my_mock.should_receive(:msg).once.and_yield(<value-0-1>, <value-0-2>,
..., <value-0-n>).
and_yield(<value-1-1>, <value-1-2>, ..., <value-1-n>).
and_yield(<value-2-1>, <value-2-2>, ..., <value-2-n>)
HTH,
Ben
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