cheat sheets.

* Associations:
    Verify that the association has been defined. 
      (doesn't verify that the association works!)

    object.should have_many(:association)
    object.should belong_to(:association)
    object.should have_one(:association)
    object.should have_and_belong_to_many(:association)
    project.should have_and_belong_to_many(:categories)

  * Validations:
    Verify that a validation has been defined.
      (doesn't test the validation itself)

    object.should validate_presence_of(:attribute)
    object.should validate_confirmation_of(:attribute)
    object.should validate_uniqueness_of(:attribute)
    object.should validate_length_of(:attribute, :within => 5..10)
    object.should validate_length_of(:attribute, :is => 5)

  * Observers:
    Verify that the observer is observing a class.
      (doesn't verify that the observation works)
    
    Class.should observe(:model)
    example: GroupObserver.should observe(Group)

  * Views:
    Verifies that the views contains some tags.

    response.should have_form_posting_to(url_or_path)
    response.should have_form_putting_to(url_or_path)
    response.should have_text_field_for(:attribute)
    response.should have_label_for(:attribute)
    response.should have_password_field_for(:attribute)
    response.should have_checkbox_for(:attribute)
    response.should have_submit_button
    response.should have_link_to(url_or_path, "optional_text")

    * have_form_*ing_to take a block so the rest can be nested