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Rails Kata - Part 1: Library

Code kata in ruby on Rails where you have to write a library of books and magazines.

A code kata is an exercise in programming which helps a programmer hone their skills through practice and repetition.


You have to implement an abstracted and simple library system.

Frame conditions

  1. You have exact 2.5 hours of time - no minute longer.

    If you reach this time limit stop your work immediately. It is one part of the kata to respect this time limit.

  2. There are no restrictions on how to use the provided time. If you want to code the entire time, take a break or a cigaret - it’s up to you.

  3. This is a real world situation. You are allowed to consult the Internet, use every library you want, call a friend ...

    BUT: You are not allowed to do pair programming. AND If you have already done this kata before to have a look at your previous implementation.

  4. Develop your code based on Rails 5.

  5. Keep the following priorities in mind while you implementing - in the mentioned order:

    1. Code quality
    2. Usage of object oriented methods
    3. Functionality
  6. Given resources:

    Hint: There is a reason why there are so many books and authors in german with umlauts.

    • authors.csv: Contains authors with its email, firstName and lastName.
    • books.csv: Contains books with its title, description, one or more authors and an isbn.
    • magazines.csv: Contains magazines with its title, one or more authors, a publishedAt and an isbn.


Main tasks

  1. Your software should read all data from the given CSV files in a meaningful structure.

  2. Print out all books and magazines (could be a GUI, console, …) with all their details (with a meaningful output format).

    Hint: Do not call printBooks(...) first and then printMagazines(...) ;-)

  3. Find a book or magazine by its isbn.

  4. Find all books and magazines by their authors’ email.

  5. Print out all books and magazines with all their details sorted by title. This sort should be done for books and magazines together.

Optional tasks

Hint: Optional means optional.

  1. Write Unit tests for one or more methods.

  2. Implement an interactive user interface for one or more of the main tasks mentioned above. This could be done by a website, on the console, etc.

  3. Add a book and a magazine to the data structure of your software and export it to a new CSV files.


  1. Get the code. There are several ways for it:

    1. With fork (makes it possible to preserve your work):

      1. Fork this repository
      2. Clone this fork to your computer:
        git clone <your github url>
        # Example: git clone
    2. Clone this repository with local branch:

      git clone
      git checkout -b run-<yourname>-<iteration number> 
      # Example: git checkout -b run-blaubaer-1
    3. Just download it from here

  2. Open in your favorite IDE.

  3. Start the kata.

  4. Discuss with your friends and/or colleges your solution.

  5. Repeat after some days/weeks.


See LICENSE file.


Coding kata for Ruby on Rails aimed to improve your development skills in continues sessions.







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