Build your own Ruby gem
As an avid Ruby on Rails user, setting up and running a Rails API with a test environment pretty much requires utilizing ruby gems all over the place. You can check my article about it here
In this article, we will build a somewhat useful gem from a Codewars kata problem.
Write a function called that takes a string of parentheses and determines if the order of the parentheses is valid. The function should return true if the string is valid, and false if it’s invalid.
“()” => true
“)(()))” => false
“(“ => false
“(())((()())())” => true
We are going to modify this problem to include an actual code in them instead of just parentheses. So our gem will notify us if we have mismatching parentheses in our code before we run it.
Creating the Gem scaffold
We are going to use Bundler gem. Bundler provides a consistent environment for Ruby projects by tracking and installing the exact gems and versions that are needed. Be sure that you have it via
$ gem install bundler command.
Bundler gives us the ability to create gems and we are going to scaffold our gem firstly.
$ bundle gem CheckParans
You will be prompted with a few yes/no questions, you should select test environment as RSpec because, of course, we are going to test our gem! Then you have a license and code of conduct prompts, you can say no to both because this will be just a test gem.
Now we should focus on
CheckParans.gemspec file, there is some setup that needs to be done in this file
We must attend to TODO’s and change them accordingly in order to proceed.
changelog_uri is not needed for now and can be deleted. Let me share with you the latest gemspec;
That should do it! We are ready to write our tests but run
$ bundle install on your command line first to get RSpec ready.
Testing with RSpec
Our test file is created when we scaffolded the project, it is located at
spec/CheckParans_spec.rb , let’s add some simple tests to that;
If you type
$ rspec now it will say that
undefined method 'valid_parentheses' as expected, let’s go and define our core functionality to
This will check if the parentheses are valid in any given string, return false or true depending on validity. Now if we try to run
$ rspec on CLI, all tests should be green!
Build the Gem
Only the easiest part left now, we just need to run the following command;
$ gem build CheckParans.gemspec
Gem file is created and now we can install it like we do with other gem packages
$ gem install CheckParans-0.1.0.gem
Our in house made gem package is ready to use, you can type
$ gem list and find installed gem packages in the system. CheckParans is there! (and also I realized that we didn’t obey naming conventions but that’s not the point now)
Use the Gem
Since the gem is installed we can require it any rb file we wish
our_test_code_2 has an extra invalid parenthese at the end of the code. Our gem provides us functionality to check it, we will receive true and false respectively for
Next time we will look at how to publish our gem and use it with in command line!