Given the comment below to move the let's into the shared examples, this should then be"

```ruby
describe '#call' do
  context 'when the request scheme is HTTP' do
   let(:base_uri) { "#{config.alps_base_uri}" }
   it_behaves_like 'any sheme'
  end

  context 'when the request scheme is TCP' do
   let(:base_uri) { "tcp://alps.example.org" }
   it_behaves_like 'any sheme'
  end
end
```