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Active Model Lint Tests

You can test whether an object is compliant with the Active Model API by including ActiveModel::Lint::Tests in your TestCase. It will include tests that tell you whether your object is fully compliant, or if not, which aspects of the API are not implemented.

Note an object is not required to implement all APIs in order to work with Action Pack. This module only intends to provide guidance in case you want all features out of the box.

These tests do not attempt to determine the semantic correctness of the returned values. For instance, you could implement valid? to always return true, and the tests would pass. It is up to you to ensure that the values are semantically meaningful.

Objects you pass in are expected to return a compliant object from a call to to_model. It is perfectly fine for to_model to return self.

Methods
T
Instance Public methods
test_errors_aref()

Passes if the object's model responds to errors and if calling [](attribute) on the result of this method returns an array. Fails otherwise.

errors[attribute] is used to retrieve the errors of a model for a given attribute. If errors are present, the method should return an array of strings that are the errors for the attribute in question. If localization is used, the strings should be localized for the current locale. If no error is present, the method should return an empty array.

# File activemodel/lib/active_model/lint.rb, line 101
def test_errors_aref
  assert model.respond_to?(:errors), "The model should respond to errors"
  assert model.errors[:hello].is_a?(Array), "errors#[] should return an Array"
end
test_model_naming()

Passes if the object's model responds to model_name both as an instance method and as a class method, and if calling this method returns a string with some convenience methods: :human, :singular and :plural.

Check ActiveModel::Naming for more information.

# File activemodel/lib/active_model/lint.rb, line 80
def test_model_naming
  assert model.class.respond_to?(:model_name), "The model class should respond to model_name"
  model_name = model.class.model_name
  assert model_name.respond_to?(:to_str)
  assert model_name.human.respond_to?(:to_str)
  assert model_name.singular.respond_to?(:to_str)
  assert model_name.plural.respond_to?(:to_str)

  assert model.respond_to?(:model_name), "The model instance should respond to model_name"
  assert_equal model.model_name, model.class.model_name
end
test_persisted?()

Passes if the object's model responds to persisted? and if calling this method returns either true or false. Fails otherwise.

persisted? is used when calculating the URL for an object. If the object is not persisted, a form for that object, for instance, will route to the create action. If it is persisted, a form for the object will route to the update action.

# File activemodel/lib/active_model/lint.rb, line 69
def test_persisted?
  assert model.respond_to?(:persisted?), "The model should respond to persisted?"
  assert_boolean model.persisted?, "persisted?"
end
test_to_key()

Passes if the object's model responds to to_key and if calling this method returns nil when the object is not persisted. Fails otherwise.

to_key returns an Enumerable of all (primary) key attributes of the model, and is used to a generate unique DOM id for the object.

# File activemodel/lib/active_model/lint.rb, line 30
def test_to_key
  assert model.respond_to?(:to_key), "The model should respond to to_key"
  def model.persisted?() false end
  assert model.to_key.nil?, "to_key should return nil when `persisted?` returns false"
end
test_to_param()

Passes if the object's model responds to to_param and if calling this method returns nil when the object is not persisted. Fails otherwise.

to_param is used to represent the object's key in URLs. Implementers can decide to either raise an exception or provide a default in case the record uses a composite primary key. There are no tests for this behavior in lint because it doesn't make sense to force any of the possible implementation strategies on the implementer.

# File activemodel/lib/active_model/lint.rb, line 45
def test_to_param
  assert model.respond_to?(:to_param), "The model should respond to to_param"
  def model.to_key() [1] end
  def model.persisted?() false end
  assert model.to_param.nil?, "to_param should return nil when `persisted?` returns false"
end
test_to_partial_path()

Passes if the object's model responds to to_partial_path and if calling this method returns a string. Fails otherwise.

to_partial_path is used for looking up partials. For example, a BlogPost model might return “blog_posts/blog_post”.

# File activemodel/lib/active_model/lint.rb, line 57
def test_to_partial_path
  assert model.respond_to?(:to_partial_path), "The model should respond to to_partial_path"
  assert_kind_of String, model.to_partial_path
end