Stubbing chain of methods with arguments

[siva]

   Hi all

   In my controller I have code as below:

      # app/controllers/bookings_controller.rb

     @booking.unit_installments.each do |i|
        InterestAmount.new(i, Date.today, project).calculate
      end

     I have seen `stub_chain` method but I didn't find how to stub chain methods with arguments and how to verify chain methods with arguments as well. Could you help me?

    Thanks in advance.

[Xavier Shay]

What are you trying to test/assert here?
At a first glance, I'd refactor InterestAmount to provide an interface
`InterestAmount.calculate`, then you don't need to use stub_chain, and
also hide your implementation.

Cheers,
Xavier
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[siva]

  Hi Xavier

   Thanks for your reply.

   I want assert whether `calculate` has been called no. of times that loop has been iterated with the same parameters every time.

  And on class `InterestAmount` initializer I set the parameters in instance variables like as  follows so that I can use same instance variables across all methods in `InterestAmount` class.

  class InterestAmount
   def initialize(installment, date, project)
    @installment = installment
    @project = project
    @date = date
  end
  end

[Xavier Shay]

On 5/02/14 10:40 PM, siva wrote:

  Hi Xavier

   Thanks for your reply.

   I want assert whether `calculate` has been called no. of times that loop has been iterated with the same parameters every time.

  And on class `InterestAmount` initializer I set the parameters in instance variables like as  follows so that I can use same instance variables across all methods in `InterestAmount` class.

  class InterestAmount
   def initialize(installment, date, project)
    @installment = installment
    @project = project
    @date = date
  end
  end

If you do:

class InterestAmount
  def self.calculate(*args); new(*args).calculate; end
  #...
end

you hide the initializer, and subsequently your tests get much nicer. (i.e. listening to the test leads to a nicer interface)

To view this discussion on the web visit https://groups.google.com/d/msgid/rspec/444f7e07-369b-47bb-a920-5fce1a282907%40googlegroups.com.

[siva]

 
 Thanks Xavier it worked. But I need a small clarification. How could we stub chain of methods where each method asks a set of arguments?

[Myron Marston]

You can stub any arbitrary chain of methods by setting up the stubs individually:

allow(a).to receive(:foo).with(1).and_return(b = double)

allow(b).to receive(:bar).with(2).and_return(c = double)

allow(c).to receive(:baz).with(3).and_return("it worked")

expect(a.foo(1).bar(2).baz(3)).to eq("it worked")

HTH,

Myron

[Arup Rakshit]

You can stub any arbitrary chain of methods by setting up the stubs individually:

allow(a).to receive(:foo).with(1).and_return(b = double)

allow(b).to receive(:bar).with(2).and_return(c = double)

allow(c).to receive(:baz).with(3).and_return("it worked")

expect(a.foo(1).bar(2).baz(3)).to eq("it worked")

HTH,

Myron

Myron,

Is this accepted answer is wrong approach to the problem as given ? http://stackoverflow.com/a/8522108/2767755 

[Myron Marston]

That answer is fine.  It's equivalent to what I posted above, but using the older syntax (`stub`) rather than the newer `allow` syntax, and also using blocks for return values rather than `and_return`.