Rails: I can't call a function in a module in /lib - what am I doing wrong?

Question

I know I\'m doing something stupid or failing to do something intelligent - I\'m frequently guilty of both.

Here\'s an example of what\'s causing me pain:

I have

Answer 1

Today you can do it using module_function notation.

module TestFunctions
  def abc
    puts 123
  end
end

Now TestFunctions.abc prints "123"

A little more about module_function: https://apidock.com/ruby/Module/module_function

Answer 2

Try this code:

service = Class.new { extend TestFunctions }
service.method_four

Answer 3

You can also use module_function like so:

module TestFunctions
  def abc
    puts 123
  end

  module_function :abc
end

TestFunctions.abc  # => 123

Now you can include TestFunctions in class and call "abc" from within TestFunctions module.

Answer 4

I messed with this for a while and learned several things. Hopefully this will help someone else out. I am running Rails 3.2.8.

My module (utilities.rb) looks like this and is in the /lib directory of my rails app:

module Utilities

  def compute_hello(input_string)
     return "Hello #{input_string}"
  end

end

My test (my_test.rb) looks like this and is in the /test/unit directory of my rails app:

require "test_helper"
require "utilities"

class MyTest < ActiveSupport::TestCase
  include Utilities

  def test_compute_hello
    x = compute_hello(input_string="Miles")
    print x
    assert x=="Hello Miles", "Incorrect Response"
  end

end

Here are a few things to note: My test extends ActiveSupport::TestCase. This is important because ActiveSupport adds /lib to the $LOAD_PATH. (seehttp://stackoverflow.com/questions/1073076/rails-lib-modules-and)

Secondly, I needed to both "require" my module file, and also "include" the module. Lastly, it is important to note that the stuff that gets included from the module essentially gets placed in the test class. So... be careful that the module that you include doesn't start with "test_". Otherwise, Rails will attempt to run your module method as a test.

Answer 5

You need to prefix your function with the module name because modules are not classes:

Your /lib/test_functions.rb:

module TestFunctions
  def TestFunctions.abc
    puts 123
  end
end

Your code using the module method:

require 'test_functions'
TestFunctions.abc

Answer 6

You can't call a method in a Module directly. You need to include it in a class. Try this:

>> class MyTest
>>   include TestFunctions
>> end
=> MyTest
>> MyTest.new.abc
123
=> nil