module ActionDispatch::Integration::Runner

simultaneously.
can use this method to open multiple sessions that ought to be tested
By default, a single session is automatically created for you, but you

end
sess.extend(CustomAssertions)
session = open_session do |sess|

yielded to the block before being returned.
Open a new session instance. If a block is given, the new session is

def open_session(app = nil)
  dup.tap do |session|
    yield session if block_given?
  end
end