Monday, March 23, 2020

The TDD Course for Beginners : Learn by Practicing 7 Katas

Learn how to do Test Driven Development using Ruby within 4 hours. You will get:

1. The transcript of the entire course in PDF.
2. TDD in Ruby ebook in PDF, Mobi and Epub formats
3. Members only TDD tutorial website that walks you through every exercise in the course.
4. Monthly Google hangout Q&A session that supports your learning objectives.
5. All the slides used in the course in PDF format.
6. TDD Course Tools Checklist for every sub-skill covered in the course.
7. TDD in Ruby Course Outline that was used to create the course.

How do I get access to the videos and all the above goodies?

For only $9 / month, you get my support and access to all of the above. Send me payment via Paypal to to get access today!


Jeff Casimir, Principal, Jumpstart Lab


The actual coding TDD examples for Fizz Buzz and Fibonacci were really well done
During the coding exercises the refactoring of code was a good illustration of how to improve certainty of test results
Good overview of the importance of testing
Each lecture / exercise was only 5-10 minutes providing nice incremental gains in the course


The instructor's delivery was not engaging - students tune out very quickly
First 61 minutes were very high level and included no actual coding
Instructors speaking voice was monotone and slow for the entire course no inflection, jokes, or anything to keep your attention
The audio between segments varied in quality to sometimes low quality not ideal for a $200 course
Instructor used whiteboard to write notes and diagram concepts during lecture (also wrote in cursive and at least 1 time wrote off viewable screen)


We wouldn't recommend it for Turing pre-requisite work, but could be valuable supporting material for students in the class.

Mylene Reiners

When you want a theoretical background on TDD, this course is great (and the Ruby part is not too hard for people knowing only a little Ruby...)

Yury Voloshin

This is a good introduction to TDD for those who either have never used it or who have a very rudimentary understanding of it. Some of the more advanced concepts toward the end are somewhat rushed through, but I' sure that can't be helped due to time constraints and to the nature of the material. At least now I know the topics that I need to into more deeply.


This course introduces a solid foundation for practicing TDD. The instructor definitely knows what he's teaching. Information is divided in small logical and understandable chunks/lectures.

Jesse Mignac

Techniques, examples and theoretical material. This course is a really nice start to TDD with Ruby

Andrew Platkin

Very good pace and learned alot

Thom Parkin

The beginning of this course seems a bit slow and very dry. But your patience is well rewarded because the depth and detail of information provided is priceless! Mr. Paranj uses a time-tested technique of methodical presentation of ideas, one built upon the other, to its ultimate success. I am grateful and impressed by this course.

Jikku Jose

I am very happy to have such a comprehensive course from Mr. Paranj. I have been trying to do TDD in my projects for quite sometime without much success. This course helped a lot to expose much of the concepts and details one should focus on while doing TDD.  I wish the examples mentioned in "Fake It till you make it" and "Triangulation" was a bit more involved rather than the basic ones presented so that the techniques could be better understood.  I thank Mr. Paranj and Udemy for the course, it really helped me. Hope more advanced Ruby related materials can be brought out.

Pawel Jackowski

Instructor knows TDD and explains it with ease. I am quite familiar with technique and just wanted to refresh knowledge and I still recommend course. I definitely learned something about common mistakes and importance of every step in TDD sequence. I enrolled for free.

Steve Freeman

Instructor uses katas very effectively to show the patterns behind TDD. His clear examples and pointers to material for further study were very helpful and I look forward to practicing katas on my own. If you're trying to make sense of TDD I highly recommend this class!

What are the requirements?

Basic programming skills
You need to have your favorite text editor installed on your machine
You need Ruby 2.0 or above installed on your machine.

What am I going to get from this course?

Do Problem Domain Analysis
Do Solution Domain Analysis
Design Test Cases
Write Tests First
Apply Canonical Test Structure when having difficulty in writing a test first.

Who is the target audience?

Beginners to Test Driven Development
You should already know how to write programs in Ruby
You should already know how to create an instance of a class and invoke methods.

Course Description

In this course you will learn the basics of Test Driven Development. You will learn how to do Problem Domain Analysis, Solution Domain Analysis, Designing Test Cases and Writing Tests First. Learn the Basics of Test Driven Development in Ruby using this Beginner Course. This course will take 4 hours to complete.

Practice skills using 7 katas

  • Use the downloadable checklists to guide you when coding
  • Learn 3 different techniques to do Test Driven Development
  • You can be more productive if you practice TDD at work. Companies that adopt Test Driven Development are great places to work.
The material used in this course is the result of feedback from students who attended my TDD bootcamps and tutorials. This is a course designed by a developer for developers.

The concepts are first explained in a presentation. Then a coding demo illustrates how to apply the theory in practice. At the end of the lesson an exercise is given to reinforce the material.

You will learn the following concepts:
  • Assertions
  • The structure of a test
  • TDD Cycle
  • Minimal Implementation
  • Starter Test
  • Story Test
  • Next Test
  • Refactoring
  • Obvious Implementation
  • Fake It Till You Make It
  • Triangulation
  • Hiding Implementation Details
You will be able to attend interviews for companies that demand TDD skills to get a six-figure salary. Complete with working files and code samples, you'll be able to work alongside the instructor and will receive a verifiable certificate of completion upon finishing the course. I have interviewed people and I have seen the common mistakes made by candidates.

Subscribe Now

For only $9 / month, you get my support and access to all of the above. Send me payment via Paypal to to get access today!

Friday, December 02, 2016

Find gems that are depending on a given gem

To find the gems that are dependent on a given gem, you can use the following command:

gem dependency eventmachine --reverse-dependencies

Gem eventmachine-
  rake-compiler (~> 0.9.5, development)
  rake-compiler-dock (~> 0.5.1, development)
  test-unit (~> 2.0, development)
  Used by
    excon-0.51.0 (eventmachine (>= 1.0.4, development))
    thin-1.7.0 (eventmachine (>= 1.0.4, ~> 1.0))

I wanted to find out what is depending on eventmachine in my project. Because, concurrent-ruby is a better alternative to eventmachine. My suspicion was that sucker_punch gem was using it. I was wrong because as you see in the about output, it is not the culprit. The version 2.0 of sucker punch uses concurrent-ruby. Luckily, only the development environment has dependency on the eventmachin gem.

How to provide proper error messages to users of your software

Shitty error message when the Internet connection is turned off. When you do:

git remote show origin

Error is:

ssh: Could not resolve hostname nodename nor servname provided, or not known
fatal: Could not read from remote repository.
Please make sure you have the correct access rights and the repository exists.

This is meaningless error message. Does not tell the user in simple language the cause of the problem and how to resolve it. How about:

Hey, you dummy, you are not connected to the Internet. Check your Internet connection and try again.

Auto-Complete Association in Rails 5

Checkout the Rails screencast latest episode Auto-Complete Association in Rails 5.

Cool Places to Hack

Being able to upload the screenshot of Internet speed test would be great.

Wednesday, November 30, 2016

rails date_select examples

<%= date_select 'episode', 'published_at' %>

This generates date selection drop down that has 5 previous years, current year and the next 5 years.

<%= date_select 'episode', 'published_at', start_year: Date.current.year, end_year: 2000 %>

This starts from current year and goes back till year 2000.

<%= date_select 'episode', 'published_at', start_year: 1980 , end_year: Date.current.year - 10 %>

You can provide fixed start year and go back 10 years from current year as shown above.

<%= date_select 'episode', 'published_at', order: [:month, :day, :year], start_year: 1980 , end_year: Date.current.year - 10 %>

You can provide the order of month, day and year in the order option as shown above.

RubyPlus Podcast Episode 19

Friday, November 25, 2016

Dynamic Select Menus in Rails 5

Watch the latest Rails screencast on Dynamic Select Menus in Rails 5

Gilded Rose Kata

I am writing TDD in Ruby book that has a chapter on Gilded Rose Kata. I have watched the presentations by Sandi Metz and Paul on this kata. They take different approaches to solve the problem. Sandi Metz's presentation was more engaging. I thought it was a great idea when she gradually refactored by trapping one type of cheese at a time by short-circuiting the code path for a certain cheese and make those tests fail and gradually making them pass one at a time. I don't think inheritance is the right choice in the final design. The problem is we are not inheriting any behavior from the superclass. Only the state is shared between the superclass and the subclasses so composition would have been the right choice.

I liked Paul's design of wrapping the item class and not using any dynamic class creation like Sandi Metz. Paul had a great examples of making the code express the domain concepts. But fell short in the end because he failed to recognize the data duplication and perhaps missed an opportunity to make it more expressive. Sandi Metz failed to raise the level of abstraction in the unit tests. Surprising thing is when she is describing what the test does, it could have easily been made a domain specific assertion like assert_quality_decrease etc. Hopefully, my book will address these shortcomings and perhaps I will push myself to produce something that I use in a conference talk.

Paul's presentation was a bit dry but he still had some good refactoring patterns and discussion about De Morgan's Law. I never thought what I had learned in high school would be relevant to coding today.

Emily Bache Presentation
Ruby Code to Use as a Starting Point
If you would like to download the vimeo video, follow this link: