# module ActiveModel::Lint::Tests

## 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`.

### Public Instance Methods

test_errors_aref() click to toggle source

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 lib/active_model/lint.rb, line 100
    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() click to toggle source

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 lib/active_model/lint.rb, line 79
    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?() click to toggle source

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 lib/active_model/lint.rb, line 68
    def test_persisted?
      assert model.respond_to?(:persisted?), "The model should respond to persisted?"
      assert_boolean model.persisted?, "persisted?"
    end

test_to_key() click to toggle source

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 lib/active_model/lint.rb, line 29
    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() click to toggle source

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 lib/active_model/lint.rb, line 44
    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() click to toggle source

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 lib/active_model/lint.rb, line 56
    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

### Private Instance Methods

assert_boolean(result, name) click to toggle source

    # File lib/active_model/lint.rb, line 111
    def assert_boolean(result, name)
      assert result == true || result == false, "#{name} should be a boolean"
    end

model() click to toggle source

    # File lib/active_model/lint.rb, line 106
    def model
      assert @model.respond_to?(:to_model), "The object should respond to to_model"
      @model.to_model
    end