```ruby
require 'active_model/cases/helper'

module ClientSideValidations
  class ActiveModelTestBase < ::ActiveModel::TestCase
    include ::ActiveModel::Validations

    def setup
      @person = Person.new
    end
  end
end
```

Use ActiveSupport::TestCase instead of ActiveModel
user
```ruby
require 'active_model/cases/helper'

module ClientSideValidations
  class ActiveModelTestBase < ::ActiveSupport::TestCase
    include ::ActiveModel::Validations

    def setup
      @person = Person.new
    end
  end
end
```
assistant