Ruby Minitest simple test raise error - wrong number of arguments error-CodePudding

I'm trying to learn the TDD approach, to do so I'm using pure Ruby app which is responsible for formatting UK phone number. In my class I want to test if the whitespaces and are removed from given phone number. Basically I'm trying to test the Ruby .delete(' ') method.

Tested module

# lib/formatter/phone_number/uk.rb

module Formatter
  module PhoneNumber
    module Uk
      
      (...)

      def self.format(number)
        number.delete(' ')
      end
    end
  end
end

The test

# test/lib/formater/phone_number/uk_test.rb

require 'minitest/autorun'

class UkTest < Minitest::Test
  test 'remove whitespaces' do
    invalid_number = ' 44 12 12 12 12   '
    Formatter::PhoneNumber::Uk.format(invalid_number)

    assert_equal ' 4412121212'
  end
end

Which give me an error:

test/lib/formater/phone_number/uk_test.rb:6:in `test': wrong number of arguments (given 1, expected 2) (ArgumentError)

Aside from the fact that testing a method built in Ruby is not a good idea, what am I doing wrong?

CodePudding user response：

You must define a test-method (the method name must start with test_).

Inside the test method you define your assertions. In your case, you compare the expected value with the result of your method.

class UkTest < Minitest::Test
  def test_remove_whitespaces
    invalid_number = ' 44 12 12 12 12   '
    assert_equal ' 4412121212', Formatter::PhoneNumber::Uk.format(invalid_number)
  end
end

Full test in one file:

module Formatter
  module PhoneNumber
    module Uk
      def self.format(number)
        number.delete(' ')
      end
    end
  end
end

require 'minitest/autorun'

class UkTest < Minitest::Test
  def test_remove_whitespaces
    invalid_number = ' 44 12 12 12 12   '
    assert_equal ' 4412121212', Formatter::PhoneNumber::Uk.format(invalid_number)
  end
end

Same test with minitest/spec

require 'minitest/spec'
describe Formatter::PhoneNumber::Uk do
  it 'removes spaces from numbers' do
        invalid_number = ' 44 12 12 12 12   '
        _(Formatter::PhoneNumber::Uk.format(invalid_number)).must_equal(' 4412121212')
  end
end