CODEWITHSUNDEEP
rspec
ecbrodie
ecbrodie

Reputation: 11896

Rspec shared example: Access parameter in a helper method

Suppose I create an Rspec shared example group with one parameter (the business purpose of the tests are irrelevant, it is an overly simplified version of my current codebase):

shared_examples "some example group" do |parameter|
  it "does something" do
    puts "parameter=#{parameter}"

    print_the_parameter
  end

  def print_the_parameter
    puts "parameter=#{parameter}"
  end
end

I am able to access the parameter as a variable just fine with the it test block. However, I am running into an "undefined local variable or method" when I try to access parameter from a method. Why is that? I have proven in my codebase (and is prevalently shown in Rspec documentation) that the parameter is available in test blocks, lifecycle methods like before, and in let variable declarations. But why not helper methods?

Thank you.

Upvotes: 0

Views: 129

Answers (1)

Jon Rowe
Jon Rowe

Reputation: 356

This is standard Ruby scoping, the parameter passed to the block is available within the block's closure. So the evaluated string "parameter=#{parameter}" being within the closure works just fine.

What you're trying to do the same as is this:

b = "Hi!"

def a
  puts b
end

a()
# NameError (undefined local variable or method `b' for main:Object)

The solution is to wrap parameter in a let, (note I strongly encourage using a different name to prevent confusion about precedence.) e.g.

let(:param) { parameter }

This is the same (roughly) as doing:

b = "Hi!"

def a
  puts b
end

define_method(:b) { b }

a()
# Hi!
# => nil

Upvotes: 1

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