How to stub a method in ActiveSupport::TestCase

Question

In RSpec I could stub method like this:

allow(company).to receive(:foo){300}

How can I stub a method with ActiveSupport::TestCase?

I have a test like this.

class CompanyTest < ActiveSupport::TestCase
  test 'foobar' do
    company = companies(:base)
    #company.stubs(:foo).returns(300)
    assert_nil(company.calculate_bar)
  end
end

Answer 1

Minitest comes with a stub method out of the box, in case you don't wanna use external tools:

require 'minitest/mock'
class CompanyTest < ActiveSupport::TestCase
  test 'foobar' do
    company = companies(:base)
    Company.stub :foo, 300 do
      assert_nil(company.calculate_bar)
    end
  end
end

Answer 2

Minitest has some limited functionality for mocks, but I'd suggest using the mocha gem for these kinds of stubs.

The syntax for Mocha is exactly what you have on the commented out line:

class CompanyTest < ActiveSupport::TestCase
  test 'foobar' do
    company = companies(:base)
    company.stubs(:foo).returns(300)
    assert_nil(company.calculate_bar)
  end
end