Ruby – How to load a spec_helper.rb automatically in RSpec 2

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When developing gems in Ruby, I almost always need a file in which I can configure RSpec to my needs and maybe before doing that, require some helper modules which should be available in all my spec examples.

In Rails applications a file named spec/spec_helper.rb is used for that. One thing that annoys me is that in the typical Rails environment, you have to require this spec_helper.rb file in every file that contains examples for it to be loaded. In the past I had a lot of problems with this related to changing load paths and relative require paths inside the example files.

Now for my gems, I would wish to have a way to just say RSpec to require the spec_helper.rb file before loading any of the examples files. Independent of the fact if I call rspec executable, or the rake spec task which I may define in my Rakefile.

I know I can tell RSpec only the location of my spec_helper.rb is this spec_helper.rb requires all the example files manually, but I would also like to avoid the additional maintenance of that approach.

Is there a nicer way to accomplish this?

Best Answer

In RSpec 2, the /spec folder is always automatically on your load path. This means that all you need is:

require 'spec_helper'

at the top of your spec files. This will always load /spec/spec_helper.rb, and is the minimum you'll be able to get away with.

This means you don't need a horrid approach such as:

require File.join(File.dirname(File.dirname(__FILE__)), 'spec_helper.rb')

(which needs to be updated for different nesting levels).

Also you can add to your .rspec file the option: --require spec_helper, which will require this file in each spec file, without the manual require statement at the top.

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Ruby – How to write a switch statement in Ruby

Ruby uses the case expression instead.

case x
when 1..5
  "It's between 1 and 5"
when 6
  "It's 6"
when "foo", "bar"
  "It's either foo or bar"
when String
  "You passed a string"
else
  "You gave me #{x} -- I have no idea what to do with that."
end

Ruby compares the object in the when clause with the object in the case clause using the === operator. For example, 1..5 === x, and not x === 1..5.

This allows for sophisticated when clauses as seen above. Ranges, classes and all sorts of things can be tested for rather than just equality.

Unlike switch statements in many other languages, Ruby’s case does not have fall-through, so there is no need to end each when with a break. You can also specify multiple matches in a single when clause like when "foo", "bar".

Ruby – When to use RSpec let()

I always prefer let to an instance variable for a couple of reasons:

Instance variables spring into existence when referenced. This means that if you fat finger the spelling of the instance variable, a new one will be created and initialized to nil, which can lead to subtle bugs and false positives. Since let creates a method, you'll get a NameError when you misspell it, which I find preferable. It makes it easier to refactor specs, too.
A before(:each) hook will run before each example, even if the example doesn't use any of the instance variables defined in the hook. This isn't usually a big deal, but if the setup of the instance variable takes a long time, then you're wasting cycles. For the method defined by let, the initialization code only runs if the example calls it.
You can refactor from a local variable in an example directly into a let without changing the referencing syntax in the example. If you refactor to an instance variable, you have to change how you reference the object in the example (e.g. add an @).
This is a bit subjective, but as Mike Lewis pointed out, I think it makes the spec easier to read. I like the organization of defining all my dependent objects with let and keeping my it block nice and short.

A related link can be found here: http://www.betterspecs.org/#let

Best Answer

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