Red-Green-Refactor by Example

Upcase · July 15, 2016, 3:02pm

Learn the red-green-refactor loop, the primary principle of TDD. Write tests first, watch them fail, write code incrementally until the tests pass. With passing tests, use the opportunity to refactor.

This is a companion discussion topic for the original entry at https://thoughtbot.com/upcase/videos/red-green-refactor-by-example

torasakura · July 18, 2016, 9:17am

you have initialize misspelled in your exercise code.

geoffharcourt · July 18, 2016, 6:38pm

Thanks for reporting! We updated it this morning, apologies for the typo.

iamarmanjon · July 20, 2016, 11:45am

I see now that the exercise system (feedback system) is not used here. So it’s safe to assume we post a repo link on the forum to get our code reviewed?

christoomey · July 20, 2016, 2:22pm

Hey @iamarmanjon, sorry for the confusion here. The exercise included in this video’s notes is intended to provide a structure for you to try out TDD easily, but it is not an exercise in the traditional sense where the solution is the focus.

Instead, the focus is on the process. We wanted to provide a first TDD problem for you to get comfortable with the TDD workflow, taking small steps, working on each failure one at a time, etc. That said, the end result (the final spec suite and implementation) are not expected to be very interesting or different between users. Again, the process is the focus here, not the solution.

As such, we chose to provide this as part of the notes, rather than using the exercise system. That said, step 4 in the trail is a full blown exercise using our Git system where you’re asked to refactor a spec file. In that case the solution is interesting, and thus we use the exercise system.

Sorry for the confusion here, but hopefully the above clears things up. Let us know if you have any more questions.

iamarmanjon · July 20, 2016, 11:41pm

thanks @christoomey that clears up a lot.

neilp666 · July 23, 2016, 8:22pm

require “rspec/autorun”

describe Calculator do
describe “#add” do
it “returns the sum of its two arguments” do
calc = Calculator.new

  expect(calc.add(5, 10)).to eq(15)
end

end
end

Unable to run the first test (3min 52) due to the following error

uby calculator_ruby_tdd.rb
/Users/neilpatel/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in require': cannot load such file -- rspec/autorun (LoadError) from /Users/neilpatel/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in require’

andyw8 · July 23, 2016, 9:00pm

@neilp666 it sounds like you might not have the rspec gem installed. You can run the following at the command line to confirm:

gem search rspec --local

johnnadeau · August 3, 2016, 7:58pm

Sometimes I just need a simple example like this to get me back into focusing more on the process of TDD. More often than not I drift away from a strict TDD process to a process that sometimes has tests written after the fact.

WaKeMaTTa · August 19, 2016, 1:48pm

This is my solution for the exercise

gist.github.com

https://gist.github.com/WaKeMaTTa/5cbb6315841c6d1bd3b3ffebda869da7

spec.rb

# Use TDD principles to build out name functionality for a Person.
# Here are the requirements:
# - Add a method to return the full name as a string. A full name includes
#   first, middle, and last name. If the middle name is missing, there shouldn't
#   have extra spaces.
# - Add a method to return a full name with a middle initial. If the middle name
#   is missing, there shouldn't be extra spaces or a period.
# - Add a method to return all initials. If the middle name is missing, the
#   initials should only have two characters.
#

This file has been truncated. show original

Any opinion?

helphop · August 25, 2016, 5:24am

Here is my attempt. I’m still learning Ruby.

gist.github.com

https://gist.github.com/helphop/f47b885b269eea27f8b23627b988fddf

spec.rb

# Use TDD principles to build out name functionality for a Person.
# Here are the requirements:
# - Add a method to return the full name as a string. A full name includes
#   first, middle, and last name. If the middle name is missing, there shouldn't
#   have extra spaces.
# - Add a method to return a full name with a middle initial. If the middle name
#   is missing, there shouldn't be extra spaces or a period.
# - Add a method to return all initials. If the middle name is missing, the
#   initials should only have two characters.
#

This file has been truncated. show original

chrisdambrosio · August 26, 2016, 2:25am

My solution:

gist.github.com

https://gist.github.com/chrisdambrosio/d29ab979e8b1f81c8f548701f1efdd77

spec.rb

# Use TDD principles to build out name functionality for a Person.
# Here are the requirements:
# - Add a method to return the full name as a string. A full name includes
#   first, middle, and last name. If the middle name is missing, there shouldn't
#   have extra spaces.
# - Add a method to return a full name with a middle initial. If the middle name
#   is missing, there shouldn't be extra spaces or a period.
# - Add a method to return all initials. If the middle name is missing, the
#   initials should only have two characters.
#

This file has been truncated. show original

ubermonkey · September 29, 2016, 11:32pm

I’m having wrong number of arguments (given 3, expected 0) issue on line 17, which is the initialize method. The initialiser itself, along with whole spec, was copied and pasted from the show notes:

def initialize(first_name:, middle_name: nil, last_name:)
  @first_name = first_name
  @middle_name = middle_name
  @last_name = last_name
end

And actual failure happens when I am creating new Person like so:

person = Person.new("Askhat", "Maratovich", "Bikmetov")

I’m pretty sure the elephant is in the room, but could anyone point me on it?

ruby -v 2.3.1
rspec -v 3.5.3

christoomey · September 30, 2016, 12:46am

I believe the issue here is your initialize expects keyword arguments, while your usage is passing positional arguments. So instead of the Person.new as you have it, you’ll want to do:

# note: only breaking across lines for readability
person = Person.new(
  first_name: "Askhat",
  middle_name: "Maratovich",
  last_name: "Bikmetov"
)

Note: We have a Weekly Iteration on Ruby Keyword Arguments if you want to brush up.

ubermonkey · September 30, 2016, 1:02am

You won’t believe how stupid I’m feeling right now, named arguments, obviously. Much obliged!
BTW ruby could be little more articulate on this, instead of wrong number, don’t you think?

christoomey · September 30, 2016, 1:18am

I’m always in favor of better error messages

boddhisattva · December 27, 2018, 7:49am

Here’s my attempt to solving this: Red-Green-Refactor by Example related exercise as part of the Fundamentals of TDD course in Upcase (https://thoughtbot.com/upcase/videos/red-green-refactor-by-example) · GitHub . Happy to receive any feedback to improve this further.

Thank you.

Witta11 · December 11, 2020, 1:42pm

Thats what I came up with: coding-challenges/tdd-one.rb at main · Witta11/coding-challenges · GitHub

ponix4k · March 22, 2021, 4:01pm

i was gettting failed tests when the the strings are being concatenated it took me longer than i care to admit to figure out uses whitespace i used the following function to strip the white space out

def squish(s)
    s.strip.gsub(/\s+/, " ")  # this replaces the white space with an actual space
end

tuang3142 · June 2, 2021, 12:38pm

great video. here’s my solution

class Person
  def initialize(first_name:, middle_name: nil, last_name:)
    @first_name = first_name
    @middle_name = middle_name
    @last_name = last_name
  end

  def full_name
    [@first_name, @middle_name, @last_name].reject(&:nil?).join(" ")
  end

  def full_name_with_middle_initial
    return [@first_name, @last_name].join(" ") if @middle_name.nil?

    [@first_name, @middle_name[0] + ".", @last_name].reject(&:nil?).join(" ")
  end

  def initials
    return [@first_name[0], @last_name[0]].join(".") if @middle_name.nil?

    [@first_name[0], @middle_name[0], @last_name[0]].reject(&:nil?).join(".")
  end
end

RSpec.describe Person do
  describe "#full_name" do
    it "concatenates first name, middle name, and last name with spaces" do
      person = Person.new(
        first_name: "Tuan",
        middle_name: "Viet",
        last_name: "Nguyen"
      )
      expect(person.full_name).to eq "Tuan Viet Nguyen"
    end

    it "does not add extra spaces if middle name is missing" do
      person = Person.new(
        first_name: "Tuan",
        last_name: "Nguyen"
      )
      expect(person.full_name).to eq "Tuan Nguyen"
    end
  end

  describe "#full_name_with_middle_initial" do
    context "middle name is missing" do
      it "concatenates first name and last name with spaces" do
        person = Person.new(
          first_name: "Tuan",
          last_name: "Nguyen"
        )
        expect(person.full_name_with_middle_initial).to eq "Tuan Nguyen"
      end
    end

    context "middle name is not missing" do
      it "concatenates first name, middle name initial, and last name with spaces" do
        person = Person.new(
          first_name: "Tuan",
          middle_name: "Viet",
          last_name: "Nguyen"
        )
        expect(person.full_name_with_middle_initial).to eq "Tuan V. Nguyen"
      end
    end
  end

  describe "#initials" do
    context "middle name is missing" do
      it "concatenates first name initial and last name initial" do
        person = Person.new(
          first_name: "Tuan",
          last_name: "Nguyen"
        )
        expect(person.initials).to eq "T.N"
      end
    end

    context "middle name is not missing" do
      it "concatenates first name initial, middle name initial, and last name initial" do
        person = Person.new(
          first_name: "Tuan",
          middle_name: "Viet",
          last_name: "Nguyen"
        )
        expect(person.initials).to eq "T.V.N"
      end
    end
  end
end

Topic		Replies	Views
Blog post using TDD as example Testing	3	733	March 11, 2014
How granular should you do Red-Green-Refactor? Testing	1	884	April 13, 2017
Testing Fundamentals - Passing Your First Test Exercise Questions	5	2086	November 5, 2022
Testing Fundamentals - Write A Feature With Tests Exercise Questions	16	3897	April 21, 2016
True Test Driven Development Testing	3	754	February 14, 2014

Red-Green-Refactor by Example

Related Topics