Added extension exchange request builder

Necessary to build fully rendered requests -- via Liquid templates -- for an exchange.

Issue: 352
Milestone: minor

app/aspects/extensions/exchanges/request_builder.rb

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+require "dry/core"
+require "dry/monads"
+require "initable"
+
+module Terminus
+  module Aspects
+    module Extensions
+      module Exchanges
+        # Builds fully rendereed requests.
+        class RequestBuilder
+          include Deps["aspects.extensions.contextualizer", renderer: "liquid.basic"]
+          include Initable[request: Fetchers::Request]
+          include Dry::Monads[:result]
+
+          def call exchange, extension
+            context = contextualizer.call extension
+            headers = render_values :headers, exchange, context
+            body = render_values :body, exchange, context
+
+            renderer.call(exchange.template, context).split.map do |uri|
+              request[headers:, verb: exchange.verb, uri:, body:]
+            end
+          end
+
+          private
+
+          def render_values method, exchange, context
+            Hash(exchange.public_send(method)).each.with_object({}) do |(key, value), all|
+              all[key] = renderer.call value, context
+            end
+          end
+        end
+      end
+    end
+  end
+end

spec/app/aspects/extensions/exchanges/request_builder_spec.rb

@@ -0,0 +1,84 @@
+# frozen_string_literal: true
+
+require "hanami_helper"
+
+RSpec.describe Terminus::Aspects::Extensions::Exchanges::RequestBuilder do
+  subject(:builder) { described_class.new }
+
+  describe "#call" do
+    let :extension do
+      Factory.structs[
+        :extension,
+        data: {
+          "content_type" => "application/json",
+          "sort" => "desc",
+          "source_1" => "1",
+          "source_2" => "2"
+        }
+      ]
+    end
+
+    it "answers single request without rendering" do
+      exchange = Factory.structs[:extension_exchange]
+
+      expect(builder.call(exchange, extension)).to contain_exactly(
+        Terminus::Aspects::Extensions::Fetchers::Request[uri: exchange.template]
+      )
+    end
+
+    it "answers single request when headers and data are nil" do
+      exchange = Factory.structs[:extension_exchange, headers: nil, body: nil]
+
+      expect(builder.call(exchange, extension)).to contain_exactly(
+        Terminus::Aspects::Extensions::Fetchers::Request[uri: exchange.template]
+      )
+    end
+
+    it "answers single request, fully rendered" do
+      exchange = Factory.structs[
+        :extension_exchange,
+        headers: {"content_type" => "{{ extension.data.content_type }}"},
+        verb: "post",
+        template: "https://test.io/{{ extension.data.source_1 }}",
+        body: {"sort" => "{{ extension.data.sort }}"}
+      ]
+
+      expect(builder.call(exchange, extension)).to contain_exactly(
+        Terminus::Aspects::Extensions::Fetchers::Request[
+          headers: {"content_type" => "application/json"},
+          verb: "post",
+          uri: "https://test.io/1",
+          body: {"sort" => "desc"}
+        ]
+      )
+    end
+
+    it "answers mulitiple requests, fully rendered" do
+      exchange = Factory.structs[
+        :extension_exchange,
+        headers: {"content_type" => "{{ extension.data.content_type }}"},
+        verb: "post",
+        template: "https://test.io/{{ extension.data.source_1 }}\n" \
+                  "https://test.io/{{ extension.data.source_2 }}",
+        body: {"sort" => "{{ extension.data.sort }}"}
+      ]
+
+      expect(builder.call(exchange, extension)).to eq(
+        [
+          Terminus::Aspects::Extensions::Fetchers::Request[
+            headers: {"content_type" => "application/json"},
+            verb: "post",
+            uri: "https://test.io/1",
+            body: {"sort" => "desc"}
+          ],
+          Terminus::Aspects::Extensions::Fetchers::Request[
+            headers: {"content_type" => "application/json"},
+            verb: "post",
+            uri: "https://test.io/2",
+            body: {"sort" => "desc"}
+          ]
+        ]
+      )
+    end
+  end
+end