Fix flaky net/http spec (#2667)

Author: solnic

sentry-ruby/spec/contexts/with_request_mock.rb

@@ -36,4 +36,14 @@ def stub_sentry_response
   def stub_normal_response(code: "200", &block)
     sentry_stub_request(build_fake_response(code), &block)
   end
+
+  def stub_response(http, code: "200", &block)
+    fake_response = build_fake_response(code)
+
+    allow(http).to receive(:connect)
+
+    allow(http).to receive(:transport_request) do |http_obj, request|
+      block.call(request, http_obj) if block
+    end.and_return(fake_response)
+  end
 end

sentry-ruby/spec/sentry/net/http_spec.rb

@@ -370,13 +370,15 @@ def verify_spans(transaction)
       end
 
       it "doesn't mess different requests' data together when making multiple requests with Net::HTTP.start" do
+        allow_any_instance_of(Net::HTTP).to receive(:connect)
+
         Net::HTTP.start("example.com") do |http|
-          stub_normal_response(code: "200")
+          stub_response(http, code: "200")
           request = Net::HTTP::Get.new("/path?foo=bar")
           response = http.request(request)
           expect(response.code).to eq("200")
 
-          stub_normal_response(code: "404")
+          stub_response(http, code: "404")
           request = Net::HTTP::Get.new("/path?foo=bar")
           response = http.request(request)
           expect(response.code).to eq("404")