Allow connection_pool 3.x

statsig.gemspec

@@ -29,7 +29,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'simplecov-cobertura', '~> 2.1'
   s.add_runtime_dependency 'user_agent_parser', '~> 2.18.0'
   s.add_runtime_dependency 'http', '>= 4.4', '< 6.0'
-  s.add_runtime_dependency 'connection_pool', '~> 2.4', '>= 2.4.1'
+  s.add_runtime_dependency 'connection_pool', '>= 2.5.4', '< 4.0'
   s.add_runtime_dependency 'ip3country', '~> 0.2.1'
   s.add_runtime_dependency 'concurrent-ruby', '~> 1.1'
   s.add_runtime_dependency 'zlib', '>= 3.1', '< 4.0'

test/test_network.rb

@@ -182,6 +182,28 @@ def test_retry_until_out_of_retries
     assert(!e.nil?)
   end
 
+  def test_discards_failed_connection_without_masking_error
+    connection_error = IOError.new('broken connection')
+    failed_builder = FakeHTTPBuilder.new { raise connection_error }
+    builders = [failed_builder, FakeHTTPBuilder.new { FakeHTTPResponse.new }]
+
+    HTTP.stub(:use, ->(_) { builders.shift }) do
+      net = Statsig::Network.new('secret-abc', StatsigOptions.new(local_mode: false))
+      failed_response, error = net.get('https://statsigapi.net/health')
+
+      assert_nil(failed_response)
+      assert_same(connection_error, error)
+      assert(failed_builder.clients['https://statsigapi.net'].closed)
+
+      response, error = net.get('https://statsigapi.net/health')
+
+      assert_nil(error)
+      assert(response.status.success?)
+    ensure
+      net&.shutdown
+    end
+  end
+
   def test_reuses_persistent_clients_per_origin_and_drains_response_bodies
     builder = FakeHTTPBuilder.new { FakeHTTPResponse.new }
     options = StatsigOptions.new(local_mode: false, network_timeout: 2)