1 files changed, 79 insertions, 0 deletions
diff --git a/activerecord/test/cases/pooled_connections_test.rb b/activerecord/test/cases/pooled_connections_test.rb
new file mode 100644
index 0000000000..080aeb0989
--- /dev/null
+++ b/activerecord/test/cases/pooled_connections_test.rb
@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+require "cases/helper"
+require "models/project"
+require "timeout"
+
+class PooledConnectionsTest < ActiveRecord::TestCase
+  self.use_transactional_tests = false
+
+  def setup
+    @per_test_teardown = []
+    @connection = ActiveRecord::Base.remove_connection
+  end
+
+  teardown do
+    ActiveRecord::Base.clear_all_connections!
+    ActiveRecord::Base.establish_connection(@connection)
+    @per_test_teardown.each(&:call)
+  end
+
+  # Will deadlock due to lack of Monitor timeouts in 1.9
+  def checkout_checkin_connections(pool_size, threads)
+    ActiveRecord::Base.establish_connection(@connection.merge(pool: pool_size, checkout_timeout: 0.5))
+    @connection_count = 0
+    @timed_out = 0
+    threads.times do
+      Thread.new do
+        conn = ActiveRecord::Base.connection_pool.checkout
+        sleep 0.1
+        ActiveRecord::Base.connection_pool.checkin conn
+        @connection_count += 1
+      rescue ActiveRecord::ConnectionTimeoutError
+        @timed_out += 1
+      end.join
+    end
+  end
+
+  def checkout_checkin_connections_loop(pool_size, loops)
+    ActiveRecord::Base.establish_connection(@connection.merge(pool: pool_size, checkout_timeout: 0.5))
+    @connection_count = 0
+    @timed_out = 0
+    loops.times do
+      conn = ActiveRecord::Base.connection_pool.checkout
+      ActiveRecord::Base.connection_pool.checkin conn
+      @connection_count += 1
+      ActiveRecord::Base.connection.data_sources
+    rescue ActiveRecord::ConnectionTimeoutError
+      @timed_out += 1
+    end
+  end
+
+  def test_pooled_connection_checkin_one
+    checkout_checkin_connections 1, 2
+    assert_equal 2, @connection_count
+    assert_equal 0, @timed_out
+    assert_equal 1, ActiveRecord::Base.connection_pool.connections.size
+  end
+
+  def test_pooled_connection_checkin_two
+    checkout_checkin_connections_loop 2, 3
+    assert_equal 3, @connection_count
+    assert_equal 0, @timed_out
+    assert_equal 2, ActiveRecord::Base.connection_pool.connections.size
+  end
+
+  def test_pooled_connection_remove
+    ActiveRecord::Base.establish_connection(@connection.merge(pool: 2, checkout_timeout: 0.5))
+    old_connection = ActiveRecord::Base.connection
+    extra_connection = ActiveRecord::Base.connection_pool.checkout
+    ActiveRecord::Base.connection_pool.remove(extra_connection)
+    assert_equal ActiveRecord::Base.connection, old_connection
+  end
+
+  private
+
+    def add_record(name)
+      ActiveRecord::Base.connection_pool.with_connection { Project.create! name: name }
+    end
+end unless in_memory_db?