How to use let variables in rails console?

问题

using

rspec 2.6.4
rails 3.1.6

How to use let variables in rails test console?

1.9.3-p0 :032 > let(:user) { create(:user) }
NoMethodError: undefined method `let' for main:Object

Please advise, which library should be required here?

For example: below is executed in console to use stub methods in console.

require 'rspec/mocks/standalone'

Is it possible, to define and call let variables in rails console?

回答1:

If you are fine with let just creating globals, you can polyfill it like this:

def let(name)
  Object.send :instance_variable_set, "@#{name}", yield
  Object.send :define_method, name do
    Object.send :instance_variable_get, "@#{name}"
  end
end

Usage is the same as rspec:

irb(main):007:0> let(:foo) { 1 }
=> :foo
irb(main):008:0> foo
=> 1

though you really shouldn't be pasting your test code into console to debug it. It's much better to use a breakpoint tool like pry or byebug.

回答2:

let in rspec is not much more than a lazily executed and memoized method definition. If you must have in the irb you could define it like this:

 $ cat let.rb
 def let(sym)
   $let ||= {}

   define_method sym do
     $let[sym] ||= yield
   end
 end

require './let in irb or place it in .irbrc and you have your rspec-like let. Note, that rspec reevaluates let in each new example (it or specify block). Since you don't have them in irb you may need to clear your let cache manually ($let = {}) to force re-evaluation.

来源：https://stackoverflow.com/questions/48436445/how-to-use-let-variables-in-rails-console

标签

ruby

rspec

rails-console