feat: allow a custom UI to be configured

lib/pact_broker/app.rb

@@ -32,7 +32,6 @@ def initialize &block
       yield configuration
       post_configure
       prepare_database
-      prepare_app
     end
 
     # Allows middleware to be inserted at the bottom of the shared middlware stack
@@ -54,12 +53,18 @@ def use_ui_auth middleware
       @make_it_later_ui_auth.make_it_later(middleware)
     end
 
+    def use_custom_ui custom_ui
+      @custom_ui = custom_ui
+    end
+
     def call env
       running_app.call env
     end
 
     private
 
+    attr_reader :custom_ui
+
     def post_configure
       configure_logger
       SuckerPunch.logger = configuration.custom_logger || SemanticLogger['SuckerPunch']
@@ -101,6 +106,7 @@ def prepare_app
       configure_middleware
 
       # need this first so UI login logic is performed before API login logic
+      @cascade_apps << build_custom_ui if custom_ui
       @cascade_apps << build_ui
 
       if configuration.enable_diagnostic_endpoints
@@ -139,6 +145,14 @@ def build_ui
       builder
     end
 
+    def build_custom_ui
+      logger.info "Mounting Custom UI"
+      builder = ::Rack::Builder.new
+      builder.use Rack::PactBroker::AcceptsHtmlFilter
+      builder.run @custom_ui
+      builder
+    end
+
     def build_api
       logger.info "Mounting PactBroker::API"
       require 'pact_broker/api'
@@ -174,6 +188,7 @@ def configure_logger
 
     def running_app
       @running_app ||= begin
+        prepare_app
         apps = @cascade_apps
         @app_builder.map "/" do
           run Rack::Cascade.new(apps)

spec/lib/pact_broker/app_spec.rb

@@ -65,6 +65,28 @@ def self.calls
       end
     end
 
+    describe "use_custom_ui" do
+      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
+
+      context "when the UI returns a 404 response" do
+        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_xxx_auth" do
       class TestAuth
         def initialize app, *args, &block