Using Rspec DescribeMethod

Using Rspec DescribeMethod is super simple.

In your Gemfile:

group :development, :testing do
  gem 'rspec-describe-method'
end

In your spec_helper.rb:

require 'rspec/describe-method'

And your specs can look like this:

describe String do
    describe_method '.new' do
        it{ should be_a String }
    end

    describe_method '#concat', 'argument' do
        it{ should match /argument/i }
    end

    context 'with an instance' do
        subject{ String.new 'test' }

        describe_method '#upcase' do
            it{ should eq 'TEST' }
        end
    end
end

Describe a method call on the current test subject in your specs with 'describe_method', and a # for instance methods and a . for class methods.

Instances will automatically delagate to their class, and classes will automatically create an instance of themselves.

Alias method: when_calling

The alias method when_calling is provided which makes specs more human-readable, especially when calls are nested within eachother:

describe String do
    subject{ String.new 'test' }

    when_calling '#upcase' {
        it{ should eq 'TEST' }

        when_calling '#+', 'ING' {
            it{ should eq 'TESTING' }
        }
    }
end

NOTE

When the subject is a Class, and you call an instance method describe_method "#something" the class will call .new on itself with NO ARGUMENTS, you may not want this behavior.