Rspec: How to stub a method evaluated in a block

Question

I have the following code (removed unrelated parts):

# Picture.rb
image_accessor :image_file do
  puts "config: #{Config.get(:preprocess_image_resize).present?}"
end

image_accessor is provided by dragonfly.

I want to stub Config.get (which works great for many other specs in other scenarios), but here it does not have any effect.

This is the test:

it "should resize the image file to the given value" do
  Config.stub!(:get) { |arg| arg == :preprocess_image_resize ? '1x1' : false }
end

When running the test I expect to see "config: true" in the console. But I always get "config: false".

I cant explain why - perhaps because of the evaluation in the block?

Any ideas how to stub this then?

How/when is the picture being instantiated? That it's in a block in itself shouldn't matter. — Dave Newton, May 17 '13 at 15:22
The picture is being instantiated in the spec, after the stub. — Robin, May 17 '13 at 16:25

score 0 · Answer 1 · edited May 23 '17 at 10:25

0

This might be one of those weird cases where do...end and curly braces are not the same in Ruby.

If so, the block is being run after Config.stub!(:get) which in that case returns nil. That would explain why Config.get(:preprocess_image_resize).present? is always false.

My advice: Try changing the code to

it "should resize the image file to the given value" do
  Config.stub!(:get) do |arg|
    arg == :preprocess_image_resize ? '1x1' : false
  end
end

and see if that helps.

edited May 23 '17 at 10:25

Community

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1

answered May 17 '13 at 15:30

awendt

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Wouldn't this be precisely the same thing? – Dave Newton May 17 '13 at 16:28
No, it's not. `do...end` and curly braces are of different precedence. Read the linked answer :) – awendt May 17 '13 at 20:13

Rspec: How to stub a method evaluated in a block

1 Answers1