Published: April 02, 2022 • 2 min read
describe block has two common syntaxes. Which should you use?
# With `RSpec` module name RSpec.describe TestedClass do end # Without module name describe TestedClass do end
Disclaimer: they both work. But I’m assuming since you’re here, you’re curious about the distinction, or want to make an informed choice.
TL;DR: I suggest using the
RSpec module name.
The global availability of
describe is called the Global Namespace
DSL. RSpec made
describe available on
Object, the default root of
all Ruby objects. The intent was to let us write specs without specifying the
All of these are valid:
# With `RSpec` module name RSpec.describe TestedClass do end # Without module name describe TestedClass do end # Called on `Object` Object.describe TestedClass do end # Called on any object TestedClass.describe TestedClass do end
However, RSpec 3 introduced a configuration to disable this namespace:
# spec/spec_helper.rb config.expose_dsl_globally = false
In suites with this setting, only
RSpec.describe is valid. The other three
examples raise a
So, why use the namespace? I use it because it’s boring and pushes my code away from magic.
It’s the boring choice. It works in any RSpec test suite, regardless of configuration. It’s the syntax rspec-rails generates. You can borrow a spec from any other test suite or copy an example from the internet and it just works.
Monkey patching and magic are contentious subjects in Ruby. They are some of the best and worst features of the language, depending on who you ask. The module name lets me skip this debate at the cost of six communicative characters.
The choice is yours!
Get better at programming by learning with me. Subscribe to my newsletter for weekly ideas, creations, and curated resources from across the world of programming. Join me today!