NameError: undefined local variable or method `logger'

You can use the Rails logger outside of models and controllers:

Rails.logger.info "..."

Source

The logger method isn't available to test cases instance methods.

You have defined a local variable in your class definition but this isn't enough. The logger variable falls out of scope once the class is initialized. You may be looking for a class variable (@@logger). But a cleaner solution would be wrapping it in a method like this.

class Test::Unit::TestCase  def logger    RAILS_DEFAULT_LOGGER ||= Logger.new(STDOUT)  endend

Notice this code will use the default logger if it is available (which it should be). If this isn't desired, you can make your own just as easily.

def logger  @logger ||= Logger.new(STDOUT)end

you should use RAILS_DEFAULT_LOGGER.debug the constant in your test case is_valid_checksum? not the variable logger(class level variable ) which cannot be used in a instance method.

I would suggest to wrap the code in a instance method something like

def logger  logger = Logger.new(STDOUT)  logger.level = Logger::WARN  loggerend

and then use logger