Last question in methods problems

I had an exchange with Tommy via email, following up here, as instructed:

In the final problem, my code should work, but throws an error. My code is

# Write a method that returns the integer remainder of its two arguments.
# (i.e., what using the modulo operator would return).
# You may not use the modulo operator.
# Assume the arguments are integers.
# HINT: Use dec_remainder_of_two_integers as a helper method

def int_remainder_without_modulo(i_dividend, i_divisor)
  var = i_dividend / i_divisor
  return i_dividend - (i_divisor * var)
end

I also have no idea what to make out of the error saying 
Failures:

  1) methods.rb int_remainder_without_modulo doesn't use the % operator

     Failure/Error: return i_dividend - (i_divisor * var)

    
     TypeError:

       coerce must return [x, y]

Tommy says: Hey Chris, your code looks like it should work. The problem is with
the spec itself. If you look at the code in the spec, the i_dividend
that’s getting sent in as an argument isn’t actually an integer. It’s
an RSpec::Mocks::Double. It’s basically a dummy stand-in. If you take
a look at the hint in the comment above the method definition, that
might point you in the right direction.

Does this mean my code works fine, but I can’t use it, because I don’t use the helper function it wants me to use?

Hey Chris,

That is the funny thing about specs. Your code is technically correct and would work in a real-life setting, but the specs are expecting your code to work a certain way and in this case, it is most likely looking for you to use the helper method.