CODEWITHSUNDEEP
ruby
Adrian
Adrian

Reputation: 16735

Ruby switch outputting unexpected value

I don't work in Ruby day-to-day, but I'm attempting to brush up on it. On exercism.io, there's an exercise I'm attempting to complete and the solution I came up with isn't working. Here's the test code:

class ResistorColorDuoTest < Minitest::Test
  def test_brown_and_black
    # skip
    assert_equal 10, ResistorColorDuo.value(["brown", "black"])
  end
end

This is the solution I came up with:

module ResistorColorDuo
    def self.value(colors)
        case colors
        when (colors - ["brown", "black"]).empty?
            10
        else
            -1
        end
    end
end

The output from the method is -1. I can't figure out what I've fouled up. Any suggestions are greatly appreciated. Thank you for reading.

Upvotes: 1

Views: 60

Answers (2)

Ben Stephens
Ben Stephens

Reputation: 3371

Based on: https://stackoverflow.com/a/42269911/14454939

colors = ["brown", "black"]

case
when (colors - ["brown", "black"]).empty?
    10
else
    -1
end
# => 10

colors = ["brown", "blue"]

case
when (colors - ["brown", "black"]).empty?
    10
else
    -1
end
# => -1

Edit: I didn't really think of it until now, but is there a reason you can't do?:

colors = ["brown", "blue"]

case colors
when ["brown", "black"]
    10
when ["brown", "blue"]
    20
else
    -1
end
# => 20

or if order shouldn't matter:

colors = ["brown", "blue"]

case colors.sort
when ["black", "brown"] #.sort if you don't want to sort manually
    10
when ["blue", "brown"]
    20
else
    -1
end
# => 20

Upvotes: 2

Ursus
Ursus

Reputation: 30071

You're using case like it was an if.

(colors - ["brown", "black"]).empty?

evalutes to true so true is compared to your colors

switch to if-else

def self.value(colors)
  if (colors - ["brown", "black"]).empty?
    10
  else
    -1
  end
end

Upvotes: 4

Related Questions