Cannot set created_at / updated_at in fixture definitions — NoMethodError

[siklodi-mariusz]

Setting created_at or updated_at on a fixture definition raises NoMethodError:

FixtureBot.define do
  user :john do
    created_at '<%= 7.months.ago %>'
  end
end

NoMethodError: undefined method 'created_at' for #<FixtureBot::Row::Definition:0x000000012e820328>

      created_at '<%= 7.months.ago %>'
      ^^^^^^^^^^

This also affects updated_at:

FixtureBot.define do
  user :john do
    updated_at '<%= 7.months.ago %>'
  end
end

Use case

Many test scenarios require fixtures with specific timestamps. For example:

• Scoping by created_at: A test for "users created more than 6 months ago" needs created_at: <%= 7.months.ago %>
• Time-window queries: Event fixtures need specific created_at to fall inside or outside a date range

Standard Rails YAML fixtures support this without issue:

# test/fixtures/users.yml
john:
 created_at: <%= 7.months.ago %>

FixtureBot should be able to express the same thing.