Fix build for rack 3.0

lib/api_valve.rb

@@ -12,6 +12,7 @@
 require 'faraday'
 require 'multi_json'
 require 'logger'
+require 'rack'
 
 module ApiValve
   autoload :Benchmarking,      'api_valve/benchmarking'

spec/examples/middlewares_spec.rb

@@ -1,6 +1,6 @@
 RSpec.describe 'Middleware example', type: :feature do
   let(:builder) { example_app 'middleware' }
-  let(:app) { builder[0] }
+  let(:app) { builder }
 
   before do
     stub_request(:get, %r{^http://api.host/api})

spec/examples/permissions_spec.rb

@@ -1,6 +1,6 @@
 RSpec.describe 'Permissions example', type: :request do
   let(:builder) { example_app 'permissions' }
-  let(:app) { builder[0] }
+  let(:app) { builder }
 
   before do
     stub_request(:get, %r{^http://api.host/api})

spec/examples/rewriting_spec.rb

@@ -1,6 +1,6 @@
 RSpec.describe 'Rewriting example', type: :feature do
   let(:builder) { example_app 'rewriting' }
-  let(:app) { builder[0] }
+  let(:app) { builder }
 
   before do
     stub_request(:get, %r{^http://api.host/api})

spec/support/helper.rb

@@ -1,6 +1,8 @@
 module Helper
   def example_app(example)
     path = Pathname.new(__FILE__).join("../../../examples/#{example}/config.ru")
-    Rack::Builder.parse_file(path.to_s)
+    # In rack 2.x parse_file returns a tuple
+    app, _config = *Rack::Builder.parse_file(path.to_s)
+    app
   end
 end