How to test a function which takes a block with rspec

mocking, rspec, rspec2, ruby, stubbing

Solution

I think what you're looking for are yield matchers, i.e:

it "should test something" do
  # just an example
  expect { |b| my_object.start(&b) }.to yield_with_no_args
end

Problem

I have a function, which accepts a block, opens a file, yields and returns: ``` def start &block .....do some stuff File.open("filename", "w") do |f| f.write("something") ....do some more stuff yield end end ``` I am trying to write a test for it using rspec. How do I stub File.open so that it passed an object f (supplied by me) to the block instead of trying to open an actual file? Something like: ``` it "should test something" do myobject = double("File", {'write' => true}) File.should_receive(:open).with(&blk) do |myobject| f.should_receive(:write) blk.should_receive(:yield) (or somethig like that) end end ```

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