Question

Like most people, I have learned Rails before Ruby and now I would like to get a better knowledge of Ruby.
I am making some scripts and I would like to test them.
I was surprised by the fact that you can’t use Rails’ test syntax in plain ruby scripts. The following code does not work:

require "test/unit"
class MyTest < Test::Unit::TestCase
  test "one plus one should be equal to two" do
    assert_equal 1 + 1, 2
  end
end

# Error: wrong number of arguments (1 for 2) (ArgumentError)

You have to use this code instead:

require "test/unit"
class MyTest < Test::Unit::TestCase
  def one_plus_one_should_be_equal_to_two
    assert_equal 1 + 1, 2
  end
end

Which seems less readable to me.
Is it possible to use the "declarative" syntax in plain Ruby scripts?

Answer 1

According to Rails’ APIs, the test method is defined inside ActiveSupport::Testing::Declarative module and uses a sort of metaprogramming to add new test methods.

If you don’t already have the Rails gem installed, you can just install the activesupport gem:

gem install activesupport

Now you just have to require it and make your class inherit from ActiveSupport::TestCase.
Here is the complete code:

require "test/unit"
require "active_support"
class MyTest < ActiveSupport::TestCase
  test "one plus one should be equal to two" do
    assert_equal 1 + 1, 2
  end
end