programming is hard

Nothing special, just a simple helper I threw together in a few minutes.  It is used in model tests to verify that a column is required.  A few usages follow.

  def should_require_attribute(model, attrib_name, error_messages=[], invalid_value=nil)
    # Collect the valid value
    valid_value = model.send(attrib_name)
    error_messages = error_messages.to_a.sort
    
    # Set it to nil
    model.send("#{attrib_name.to_s}=", invalid_value)

    model.should_not_be_valid
    model.should_have(error_messages.size).errors
    model.errors.on(attrib_name).to_a.sort.should == error_messages
    
    # Put things back where you found them
    model.send("#{attrib_name.to_s}=", valid_value)
    model.should_be_valid
  end

# Simple case
specify "should be invalid without state" do
   should_require_attribute(your_model, :state, "is required")   
end

# More than one error expected
specify "should require a valid email address" do
   should_require_attribute(your_model, :email_address, ["is required", "should be a valid format"])   
end

# Invalid value other than nil
specify "should require a non .gov email address" do
   should_require_attribute(your_model, :email_address, "can't contain .gov domains", "bigbrother@government.gov")   
end