feat: allow a custom API to be configured

lib/pact_broker/app.rb

@@ -60,6 +60,10 @@ def use_custom_ui custom_ui
       @custom_ui = custom_ui
     end
 
+    def use_custom_api custom_api
+      @custom_api = custom_api
+    end
+
     def call env
       running_app.call env
     end
@@ -182,11 +186,13 @@ def build_custom_ui
     def build_api
       logger.info "Mounting PactBroker::API"
       require 'pact_broker/api'
+      api_apps = [PactBroker::API]
+      api_apps.unshift(@custom_api) if @custom_api
       builder = ::Rack::Builder.new
       builder.use @make_it_later_api_auth
       builder.use Rack::PactBroker::Convert404ToHal
       builder.use Rack::PactBroker::DatabaseTransaction, configuration.database_connection
-      builder.run PactBroker::API
+      builder.run Rack::Cascade.new(api_apps)
       builder
     end
 

spec/lib/pact_broker/app_spec.rb

@@ -66,13 +66,15 @@ def self.calls
     end
 
     describe "use_custom_ui" do
+      before do
+        app.use_custom_ui(custom_ui)
+        get "/", nil, { "HTTP_ACCEPT" => "text/html" }
+      end
+
       context "when the UI returns a non 404 response" do
         let(:custom_ui) { double('ui', call: [200, {}, ["hello"]]) }
 
         it "returns the given page" do
-          app.use_custom_ui(custom_ui)
-
-          get "/", nil, { "HTTP_ACCEPT" => "text/html" }
           expect(last_response.body).to eq "hello"
         end
       end
@@ -81,12 +83,34 @@ def self.calls
         let(:custom_ui) { double('ui', call: [404, {}, []]) }
 
         it "passes on the call to the rest of the app" do
-          get "/", nil, { "HTTP_ACCEPT" => "text/html" }
           expect(last_response.status).to eq 200
         end
       end
     end
 
+    describe "use_custom_api" do
+      before do
+        app.use_custom_api(custom_api)
+        get "/", nil, { "HTTP_ACCEPT" => "application/hal+json" }
+      end
+
+      context "when the API returns a non 404 response" do
+        let(:custom_api) { double('api', call: [200, {}, ["hello"]]) }
+
+        it "returns the given resource" do
+          expect(last_response.body).to eq "hello"
+        end
+      end
+
+      context "when the custom API returns a 404 response" do
+        let(:custom_api) { double('api', call: [404, {}, []]) }
+
+        it "passes on the call to the rest of the app" do
+          expect(last_response.body).to_not eq "hello"
+        end
+      end
+    end
+
     describe "use_xxx_auth" do
       class TestAuth
         def initialize app, *args, &block