api_caller_spec.rb

RSpec.describe ApiCaller do
  describe '#run' do
    let(:route_builder_mock) { instance_double(RouteBuilder }
      
    before do
      allow(RouteBuilder).to receive(:new).and_return(route_builder_mock)
    end
    
    context 'route builder threw an error' do
      before do
        allow(route_builder_mock).to receive(:run).and_raise('some error')
      end
      
      # Do something
      ...
    end
    
    context 'route builder returned a proper url' do
      before do
        allow(route_builder_mock).to receive(:run).and_return('http://some.url.com')
      end

      # Do a different thing
      ...
    end
  end
end