Introduction

RSpec is a powerful testing framework for Ruby that makes testing your code a breeze. But what if you find yourself writing similar test cases again and again? Enter RSpec shared examples and shared contexts! These nifty features allow you to DRY (Don’t Repeat Yourself) up your tests by reusing common setups and expectations. In this two-part blog series, we’ll dive deep into RSpec’s shared examples and shared contexts, starting with part one.

Understanding RSpec Shared Examples

RSpec shared examples are a way to define a set of common examples (test cases) that can be reused across multiple specs (test files). They help you keep your test suite DRY by abstracting away repetitive test code.

Let’s say you’re building a blog application in Ruby, and you have two different classes, Article and Comment, both of which need to be tested for certain behaviors. Instead of duplicating the same tests in both spec files, you can create a shared example group.

Here’s how you can define a shared example group:

RSpec.shared_examples "a publishable resource" do
  it "responds to the publish method" do
    expect(subject).to respond_to(:publish)
  end

  it "is not published by default" do
    expect(subject.published?).to be false
  end
end

Using Shared Examples in Specs

Let’s see how to use the shared example group in a spec file:

describe Article do
  it_behaves_like "a publishable resource" do
    let(:subject) { Article.new }
  end
end

describe Comment do
  it_behaves_like "a publishable resource" do
    let(:subject) { Comment.new }
  end
end

In the above code, we use it_behaves_like to include the shared example group "a publishable resource" in both the Article and Comment spec files. We also define the subject for each case, which specifies the object being tested.

By doing this, you’ve eliminated duplication in your test suite. Any changes or updates to the shared example group will propagate to all spec files that use it, ensuring consistency in your tests.

Conclusion

In this first part on RSpec shared examples and shared contexts, we’ve explored how shared examples can help you keep your tests DRY by encapsulating common test cases in reusable groups. This not only saves you time but also makes your test suite more maintainable and less error-prone.

Stay tuned for part two, where we’ll delve into shared contexts and how they can further enhance your RSpec testing experience. Until then, start cleaning up your specs by harnessing the power of shared examples!