jQuery plugin to do sanity checks on your selectors

assert.coffee

# I live in constant fear of velociraptors, hipsters, and the risk that my jQuery 
# selectors won't match the DOM at runtime.
#
# I've been using this pattern lately to assert that a jQuery object contains the
# elements that I expect.  BeatLab.warn is a wrapper around the hoptoad notifier 
# that sends me a warning message with a stacktrace.
#
# This is of course not a replacement for good unit tests, for which I highly 
# recommend jasmine.
#
# Example:
#    $('#please_be_there').assert().show()
#    $('.a_few_things').assert(3).hide()
#
jQuery.fn.assert = (length) ->
  if length?
    if length != @length
      BeatLab.warn("Expected '#{@selector}' to match #{length} elements")
  else
    if @length == 0
      BeatLab.warn("Expected '#{@selector}' to match some elements")

  this