The LogMixin module provides (you guessed it) a mixin to make logging more convenient. It is intended to work both with and without Rails, to silence logging in tests by default but provide access to it when explicitly requested, to log to stderr (or Rails.logger) by default but accept other logging targets, and other conveniences.

Released under the three-clause BSD open source license. http://opensource.org/licenses/BSD-3-Clause

class Foo
  include LogMixin

  def do_something_harmless
    self.debug("Arcane internal debugging parameters: foo=#{foo} bar=#{bar}")
    self.info("Doing something harmless...")
    # ...
  end

  def do_something_risky
    if self.on_fire?
      self.err("Ignition initiated")
      self.fatal("HELP!  I'm on fire!") if on_fire
    else
      self.warn("Temperature is rising, but not on fire yet")
    end
    # ...
  end
end

By default, log messages are silenced during tests. This is usually what you want.

Sometimes you may want to test logging behavior. It's usually not advisable to test the content of log messages. If you know what you're signing up for, you might test that an INFO message was logged rather than a WARNING, however. Be careful -- you're creating an implicit contract. That having been said, here is how you can test log messages in RSpec:

it 'should log correctly' do
  obj = MyClass.new
  obj.__handle.msgs.should have(0).messages
  obj.do_something_that_logs_twice
  obj.__handle.msgs.should have(2).messages
  obj.do_something_that_logs_an_error
  obj.__handle.msgs.select {|msg| msg =~ /ERROR/}.should have(1).message
end

What if you're running your tests and you have a bug, but you can't figure out what's going on, so you actually want to see the log messages? Well, you can. Here is how you activate logging during tests, which you should presumably only do temporarily:

  ['TESTING', 'RAILS'].each do |c|
    LogMixin.send(:remove_const, c)
    LogMixin.const_set(c, false)
  end

LogMixin supports both inclusion (i.e., instances of the class get the logging methods) and extension (i.e., the class or module itself get the logging methods).

class ChattyInstance
  include LogMixin
  ...
end

module ChattyModule
  extend LogMixin
  ...
end

c = ChattyInstance.new
c.info("I'm an instance!")
ChattyModule.info("I'm a module!")
LogMixin.info("You can even log with LogMixin itself...")
LogMixin.warn("...but 'mixin' is a bit of a misnomer in that case.")

Want to change the log message format? You have lots of flexibility. See the documentation for #configure_logs and VBLM_DEFAULT_FORMAT.