fix: do not subclass session class to make it play along with default

class overrides

the faraday adapter was relying on subclassing the session to load
custom plugins. this doesn't play well with other integrations
monkeypatching the original session class, such as datadog or webmock,
which redefine it. from now on, we not only defer the creation of the
custom until necessary, we also use Session#plugin

Fixes #187

lib/httpx/adapters/faraday.rb

@@ -99,33 +99,31 @@ module Faraday
         end
       end
 
-      class Session < ::HTTPX::Session
-        plugin(:compression)
-        plugin(:persistent)
-
-        module ReasonPlugin
+      module ReasonPlugin
+        if RUBY_VERSION < "2.5"
+          def self.load_dependencies(*)
+            require "webrick"
+          end
+        else
+          def self.load_dependencies(*)
+            require "net/http/status"
+          end
+        end
+        module ResponseMethods
           if RUBY_VERSION < "2.5"
-            def self.load_dependencies(*)
-              require "webrick"
+            def reason
+              WEBrick::HTTPStatus::StatusMessage.fetch(@status)
             end
           else
-            def self.load_dependencies(*)
-              require "net/http/status"
-            end
-          end
-          module ResponseMethods
-            if RUBY_VERSION < "2.5"
-              def reason
-                WEBrick::HTTPStatus::StatusMessage.fetch(@status)
-              end
-            else
-              def reason
-                Net::HTTP::STATUS_CODES.fetch(@status)
-              end
+            def reason
+              Net::HTTP::STATUS_CODES.fetch(@status)
             end
           end
         end
-        plugin(ReasonPlugin)
+      end
+
+      def self.session
+        @session ||= ::HTTPX.plugin(:compression).plugin(:persistent).plugin(ReasonPlugin)
       end
 
       class ParallelManager
@@ -161,7 +159,6 @@ module Faraday
         include RequestMixin
 
         def initialize
-          @session = Session.new
           @handlers = []
         end
 
@@ -174,7 +171,7 @@ module Faraday
         def run
           env = @handlers.last.env
 
-          session = @session.with(options_from_env(env))
+          session = HTTPX.session.with(options_from_env(env))
           session = session.plugin(:proxy).with(proxy: { uri: env.request.proxy }) if env.request.proxy
           session = session.plugin(OnDataPlugin) if env.request.stream_response?
 
@@ -205,7 +202,7 @@ module Faraday
 
       def initialize(app, options = {})
         super(app)
-        @session = Session.new(options)
+        @session_options = options
       end
 
       def call(env)
@@ -221,7 +218,9 @@ module Faraday
           return handler
         end
 
-        session = @session.with(options_from_env(env))
+        session = HTTPX.session
+        session = session.with(@session_options) unless @session_options.empty?
+        session = session.with(options_from_env(env))
         session = session.plugin(:proxy).with(proxy: { uri: env.request.proxy }) if env.request.proxy
         session = session.plugin(OnDataPlugin) if env.request.stream_response?
 

standalone_tests/faraday_with_webmock_test.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+require "test_helper"
+require "support/http_helpers"
+require "support/minitest_extensions"
+require "httpx/adapters/faraday"
+require "webmock/minitest"
+require "httpx/adapters/webmock"
+
+class FaradayWithWebmockTest < Minitest::Test
+  include HTTPHelpers
+
+  def setup
+    super
+    WebMock.enable!
+    WebMock.disable_net_connect!
+  end
+
+  def teardown
+    super
+    WebMock.reset!
+    WebMock.allow_net_connect!
+    WebMock.disable!
+  end
+
+  def test_0_19_5_bug_faraday_and_webmock_dont_play_along
+    stub_http_request(:any, "https://www.smthfishy.com").to_return(status: 200)
+    faraday = Faraday.new { |builder| builder.adapter :httpx }
+    response = faraday.get("https://www.smthfishy.com/")
+    assert response.status == 200
+  end
+end