Writing a test for a case statement in Ruby - ruby

Question

I'm trying to write a test for a case statement using minitest. Would I need to write separate tests for each "when"? I included my code below. Right now it just puts statements, but eventually it's going to redirect users to different methods. Thanks!
require 'pry'
require_relative 'messages'
class Game
attr_reader :user_answer
def initialize(user_answer = gets.chomp.downcase)
#user_answer = user_answer
end
def input
case user_answer
when "i"
puts "information"
when "q"
puts "quitter"
when "p"
puts "player play"
end
end
end

Answer 1

This answer will help you. Nonetheless I'll post one way of applying it to your situation. As suggested by #phortx when initializing a game, override the default user-input with the relevant string. Then by using assert_output we can do something like:
#test_game.rb
require './game.rb' #name and path of your game script
require 'minitest/autorun' #needed to run tests
class GameTest < MiniTest::Test
def setup
#game_i = Game.new("i") #overrides default user-input
#game_q = Game.new("q")
#game_p = Game.new("p")
end
def test_case_i
assert_output(/information\n/) {#game_i.input}
end
def test_case_q
assert_output(/quitter\n/) {#game_q.input}
end
def test_case_p
assert_output(/player play\n/) {#game_p.input}
end
end
Running the tests...
$ ruby test_game.rb
#Run options: --seed 55321
## Running:
#...
#Finished in 0.002367s, 1267.6099 runs/s, 2535.2197 assertions/s.
#3 runs, 6 assertions, 0 failures, 0 errors, 0 skips

Answer 2

You have to test each case branch. Via RSpec it would work that way:
describe Game do
subject { Game }
describe '#input' do
expect_any_instance_of(Game).to receive(:puts).with('information')
Game.new('i').input
expect_any_instance_of(Game).to receive(:puts).with('quitter')
Game.new('q').input
expect_any_instance_of(Game).to receive(:puts).with('player play')
Game.new('p').input
end
end
However due the fact that puts is ugly to test, you should refactor your code to something like that:
require 'pry'
require_relative 'messages'
class Game
attr_reader :user_answer
def initialize(user_answer = gets.chomp.downcase)
#user_answer = user_answer
end
def input
case user_answer
when "i"
"information"
when "q"
"quitter"
when "p"
"player play"
end
end
def print_input
puts input
end
end
Then you can test with RSpec via:
describe Game do
subject { Game }
describe '#print_input' do
expect_any_instance_of(Game).to receive(:puts).with('quitter')
Game.new('q').print_input
end
describe '#input' do
expect(Game.new('i').input).to eq('information')
expect(Game.new('q').input).to eq('quitter')
expect(Game.new('i').input).to eq('player play')
expect(Game.new('x').input).to eq(nil)
end
end