CODEWITHSUNDEEP
rubyrspecrspec-mocks
xeroshogun
xeroshogun

Reputation: 1092

In RSpec, how can I mock a method called with a constant argument?

I'm creating a gem that will have a constant in whatever app it is being used in (after a generator is run), but that constant doesn't exist in the gem itself. I'm having an issue with RSpec inside the gem not skipping over the part of code that is calling the constant. A simple example of what is going on is below.

class Foo
  def self.do_something
    Bar.send(FakeConstant.name)  #Bar.send is a valid class and method
  end
end

foo_spec.rb

it 'does something'
  expect(Bar).to receive(send).and_return('skipped!')
  Foo.do_something
end

rspec output

NameError: uninitialized constant FakeConstant

I want to write the test so that it skips over the Bar.send call completely so that it never knows that there is a bad constant inside of it. There really isn't a good way to get around this.

Upvotes: 1

Views: 2386

Answers (1)

Dave Schweisguth
Dave Schweisguth

Reputation: 37627

RSpec's stub_const method allows you to stub a constant:

it 'does something'
  stub_const(FakeConstant, double(name: "Fakey McFakerson"))
  expect(Bar).to receive(send).and_return('skipped!')
  Foo.do_something
end

More here: https://www.relishapp.com/rspec/rspec-mocks/docs/mutating-constants/stub-defined-constant

That said, I agree with BroiSatse that it would be probably be nicer to provide a more dynamic means of getting that information into your code that could be manipulated in tests with less trickery.

Upvotes: 3

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