Add linter for serializable resource

lib/active_model/serializer.rb

@@ -6,6 +6,7 @@ module ActiveModel
     autoload :Configuration
     autoload :ArraySerializer
     autoload :Adapter
+    autoload :Lint
     include Configuration
 
     class << self

lib/active_model/serializer/lint.rb

@@ -0,0 +1,117 @@
+module ActiveModel::Serializer::Lint
+  # == Active \Model \Serializer \Lint \Tests
+  #
+  # You can test whether an object is compliant with the Active \Model \Serializers
+  # API by including <tt>ActiveModel::Serializer::Lint::Tests</tt> 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 Active \Model \Serializers. 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 <tt>serializable_hash</tt> to
+  # always return +{}+, and the tests would pass. It is up to you to ensure
+  # that the values are semantically meaningful.
+  module Tests
+
+    # Passes if the object responds to <tt>serializable_hash</tt> and if it takes
+    # zero or one arguments.
+    # Fails otherwise.
+    #
+    # <tt>serializable_hash</tt> returns a hash representation of a object's attributes.
+    # Typically, it is implemented by including ActiveModel::Serialization.
+    def test_serializable_hash
+      assert_respond_to resource, :serializable_hash, "The resource should respond to serializable_hash"
+      resource.serializable_hash
+      resource.serializable_hash(nil)
+    end
+
+    # Passes if the object responds to <tt>read_attribute_for_serialization</tt>
+    # and if it requires one argument (the attribute to be read).
+    # Fails otherwise.
+    #
+    # <tt>read_attribute_for_serialization</tt> gets the attribute value for serialization
+    # Typically, it is implemented by including ActiveModel::Serialization.
+    def test_read_attribute_for_serialization
+      assert_respond_to resource, :read_attribute_for_serialization, "The resource should respond to read_attribute_for_serialization"
+      assert_equal resource.method(:read_attribute_for_serialization).arity, 1
+    end
+
+    # Passes if the object responds to <tt>as_json</tt> and if it takes
+    # zero or one arguments.
+    # Fails otherwise.
+    #
+    # <tt>as_json</tt> returns a hash representation of a serialized object.
+    # It may delegate to <tt>serializable_hash</tt>
+    # Typically, it is implemented either by including ActiveModel::Serialization
+    # which includes ActiveModel::Serializers::JSON.
+    # or by the JSON gem when required.
+    def test_as_json
+      assert_respond_to resource, :as_json
+      resource.as_json
+      resource.as_json(nil)
+    end
+
+    # Passes if the object responds to <tt>to_json</tt> and if it takes
+    # zero or one arguments.
+    # Fails otherwise.
+    #
+    # <tt>to_json</tt> returns a string representation (JSON) of a serialized object.
+    # It may be called on the result of <tt>as_json</tt>.
+    # Typically, it is implemented on all objects when the JSON gem is required.
+    def test_to_json
+      assert_respond_to resource, :to_json
+      resource.to_json
+      resource.to_json(nil)
+    end
+
+    # Passes if the object responds to <tt>cache_key</tt> and if it takes no
+    # arguments.
+    # Fails otherwise.
+    #
+    # <tt>cache_key</tt> returns a (self-expiring) unique key for the object,
+    # which is used by the adapter.
+    # It is not required unless caching is enabled.
+    def test_cache_key
+      assert_respond_to resource, :cache_key
+      assert_equal resource.method(:cache_key).arity, 0
+    end
+
+    # Passes if the object responds to <tt>id</tt> and if it takes no
+    # arguments.
+    # Fails otherwise.
+    #
+    # <tt>id</tt> returns a unique identifier for the object.
+    # It is not required unless caching is enabled.
+    def test_id
+      assert_respond_to resource, :id
+      assert_equal resource.method(:id).arity, 0
+    end
+
+    # Passes if the object's class responds to <tt>model_name</tt> and if it
+    # is in an instance of +ActiveModel::Name+.
+    # Fails otherwise.
+    #
+    # <tt>model_name</tt> returns an ActiveModel::Name instance.
+    # It is used by the serializer to identify the object's type.
+    # It is not required unless caching is enabled.
+    def test_model_name
+      resource_class = resource.class
+      assert_respond_to resource_class, :model_name
+      assert_instance_of resource_class.model_name, ActiveModel::Name
+    end
+
+    private
+
+    def resource
+      @resource
+    end
+
+    def assert_instance_of(result, name)
+      assert result.instance_of?(name), "#{result} should be an instance of #{name}"
+    end
+
+  end
+end

test/lint_test.rb

@@ -0,0 +1,44 @@
+require 'test_helper'
+
+module ActiveModel
+  class Serializer
+    class LintTest < Minitest::Test
+      include ActiveModel::Serializer::Lint::Tests
+
+      class CompliantResource
+        def serializable_hash(options = nil)
+
+        end
+
+        def read_attribute_for_serialization(name)
+
+        end
+
+        def as_json(options = nil)
+
+        end
+
+        def to_json(options = nil)
+
+        end
+
+        def cache_key
+
+        end
+
+        def id
+
+        end
+
+        def self.model_name
+          @_model_name ||= ActiveModel::Name.new(self)
+        end
+      end
+
+      def setup
+        @resource = CompliantResource.new
+      end
+
+    end
+  end
+end