Figure out which tests are causing weird warnings.

example_controller_test.rb

class ExampleControllerTest < Test::Unit
  # setup etc.

  test "something should do something" do
    get :new
    # assert something
  end
  
  # more tests
end

running_tests_with_modification.sh

/path/to/some/_partial.html.erb:48: warning: Object#id will be deprecated; use Object#object_id
.test_something_should_do_something(ExampleControllerTest)

some_partial.html.erb

<li>
  <%= @something.try(:id) %>
</li>

test_modification.rb

def teardown
  puts "#{name}\n"
end