Within a factory definition, the add_attribute method defines a key/value pair that will be set when the object is built.

The add_attribute method takes two arguments: a name (Symbol or String) and a block. This block is called each time this object is constructed. The block is not called when the attribute is overriden by a build strategy.

Assignment is done by calling the Ruby attribute setter. For example, given

FactoryBot.define do
  factory :user do
    add_attribute(:name) { "Acid Burn" }

This will use the #name= setter:

user = = "Acid Burn"

Also see method_missing for a shorthand.