Stubs

Stubs are classes that build a network response from provided values instead of performing a real network call. They are used in tests to control output. Stubs have a 1:1 mapping to Smithy structure shapes.

The stub classes take an empty Response object and valid stubbing data as a hash. Following protocol rules, the Response object is populated with the data as if it came from a service response.

module SampleService
  # @api private
  module Stubs

    class CreateHighScore
      def self.build(params, context:)
        Params::CreateHighScoreOutput.build(params, context: context)
      end

      def self.validate!(output, context:)
        Validators::CreateHighScoreOutput.validate!(output, context: context)
      end

      def self.default(visited = [])
        {
          high_score: HighScoreAttributes.default(visited),
          location: 'location',
        }
      end

      def self.stub(http_resp, stub:)
        data = {}
        http_resp.status = 201
        http_resp.headers['Location'] = stub[:location] unless stub[:location].nil? || stub[:location].empty?
        http_resp.headers['Content-Type'] = 'application/json'
        data = Stubs::HighScoreAttributes.stub(stub[:high_score]) unless stub[:high_score].nil?
        http_resp.body.write(Hearth::JSON.dump(data))
      end
    end

  end
end

The Response object is populated with a status code, a body, and any appropriate headers. The Response object is eventually parsed by the parser middleware into an output object with a corresponding Type or as an error.

Default values are provided in a class method and are built in a nested context. When no values are provided, the defaults for all structures are used. When any value is provided, all other values are nil. Structures can be recursive, so previously visited defaults are tracked and checked.