Rewrite Middleware without sinatra

lib/puma/acme/middleware.rb

@@ -3,25 +3,34 @@
 module Puma
   module Acme
     # ACME challenge response handler for HTTP-01 challenges.
-    class Middleware < Sinatra::Base
+    class Middleware
       def initialize(app, manager:)
         @app = app
         @manager = manager
+      end
 
-        super(app)
+      def call(env)
+        dup._call(env)
       end
 
-      get '/.well-known/acme-challenge/:token' do
-        if (token = params[:token]).nil?
+      def _call(env)
+        if (token = token(env)).nil?
           return @app.call(env)
         end
 
         if (answer = @manager.answer(type: CHALLENGE_TYPE, token: token)).nil?
           return @app.call(env)
         end
 
-        content_type 'text/plain'
-        answer.value
+        [200, {'content-type' => 'text/plain;charset=utf-8'}, [answer.value]]
+      end
+
+      private
+
+      def token(env)
+        path = ::Rack::Request.new(env).path_info
+        prefix = '/.well-known/acme-challenge/'
+        path[prefix.size..-1] if path.start_with?(prefix)
       end
     end
   end

puma-acme.gemspec

@@ -30,6 +30,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'minitest', '~> 5.14'
   s.add_development_dependency 'minitest-mock_expectations', '~> 1.2'
   s.add_development_dependency 'r509', '~> 1.0'
+  s.add_development_dependency 'rack-test'
   s.add_development_dependency 'rake', '~> 13.0'
   s.add_development_dependency 'vcr', '~> 6.1'
   s.add_development_dependency 'webmock', '~> 3.19'

test/puma/acme/middleware_test.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+require_relative '../.././test_helper'
+require "rack/test"
+
+module Puma
+  module Acme
+    class MiddlewareTest < Minitest::Test
+      include ::Rack::Test::Methods
+
+      def test_it_returns_the_manager_answer_value_when_present
+        get '/.well-known/acme-challenge/good-token'
+        assert_equal '42', last_response.body
+        assert_equal 'text/plain;charset=utf-8', last_response.headers['content-type']
+      end
+
+      def test_it_passes_through_if_manager_provides_no_answer
+        get '/.well-known/acme-challenge/unknown-token'
+        assert_equal 'request not handled by middleware', last_response.body
+      end
+
+      def test_it_passes_unrecognized_requests_through
+        get '/'
+        assert_equal 'request not handled by middleware', last_response.body
+
+        get '/any-other/path'
+        assert_equal 'request not handled by middleware', last_response.body
+      end
+
+      class App
+        def call(env)
+          [200, {}, ['request not handled by middleware']]
+        end
+      end
+
+      class FakeManager
+        class Answer
+          def initialize(value)
+            @value = value
+          end
+          attr_reader :value
+        end
+
+        def answer(type:, token:)
+          Answer.new('42') if token == 'good-token'
+        end
+      end
+
+      def app
+        Puma::Acme::Middleware.new(
+          App.new,
+          manager: FakeManager.new
+        )
+      end
+    end
+  end
+end