diff --git a/test/serializers/reflection_test.rb b/test/serializers/reflection_test.rb
new file mode 100644
index 00000000..e5932aba
--- /dev/null
+++ b/test/serializers/reflection_test.rb
@@ -0,0 +1,389 @@
+require 'test_helper'
+module ActiveModel
+  class Serializer
+    class ReflectionTest < ActiveSupport::TestCase
+      class Blog < ActiveModelSerializers::Model
+        attributes :id
+      end
+      class BlogSerializer < ActiveModel::Serializer
+        type 'blog'
+        attributes :id
+      end
+
+      setup do
+        @expected_meta = { id: 1 }
+        @expected_links = { self: 'no_uri_validation' }
+        @empty_links = {}
+        model_attributes = { blog: Blog.new(@expected_meta) }
+        @model = Class.new(ActiveModelSerializers::Model) do
+          attributes(*model_attributes.keys)
+
+          def self.name
+            'TestModel'
+          end
+        end.new(model_attributes)
+        @instance_options = {}
+      end
+
+      # TODO: Remaining tests
+      # test_reflection_value_block_with_scope
+      # test_reflection_value_uses_serializer_instance_method
+      # test_reflection_excluded_eh_blank_is_false
+      # test_reflection_excluded_eh_if
+      # test_reflection_excluded_eh_unless
+      # test_evaluate_condition_symbol_serializer_method
+      # test_evaluate_condition_string_serializer_method
+      # test_evaluate_condition_proc
+      # test_evaluate_condition_proc_yields_serializer
+      # test_evaluate_condition_other
+      # test_options_key
+      # test_options_polymorphic
+      # test_options_serializer
+      # test_options_virtual_value
+      # test_options_namespace
+
+      def test_reflection_value
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+
+        # Assert
+        assert_nil reflection.block
+        assert_equal Serializer.config.include_data_default, reflection.options.fetch(:include_data_setting)
+        assert_equal true, reflection.options.fetch(:include_data_setting)
+
+        include_slice = :does_not_matter
+        assert_equal @model.blog, reflection.value(serializer_instance, include_slice)
+      end
+
+      def test_reflection_value_block
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            object.blog
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+
+        # Assert
+        assert_respond_to reflection.block, :call
+        assert_equal Serializer.config.include_data_default, reflection.options.fetch(:include_data_setting)
+        assert_equal true, reflection.options.fetch(:include_data_setting)
+
+        include_slice = :does_not_matter
+        assert_equal @model.blog, reflection.value(serializer_instance, include_slice)
+      end
+
+      def test_reflection_value_block_with_explicit_include_data_true
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            include_data true
+            object.blog
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+
+        # Assert
+        assert_respond_to reflection.block, :call
+        assert_equal Serializer.config.include_data_default, reflection.options.fetch(:include_data_setting)
+        assert_equal true, reflection.options.fetch(:include_data_setting)
+
+        include_slice = :does_not_matter
+        assert_equal @model.blog, reflection.value(serializer_instance, include_slice)
+      end
+
+      def test_reflection_value_block_with_include_data_false_mutates_the_reflection_include_data
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            include_data false
+            object.blog
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+
+        # Assert
+        assert_respond_to reflection.block, :call
+        assert_equal true, reflection.options.fetch(:include_data_setting)
+        include_slice = :does_not_matter
+        assert_nil reflection.value(serializer_instance, include_slice)
+        assert_equal false, reflection.options.fetch(:include_data_setting)
+      end
+
+      def test_reflection_value_block_with_include_data_if_sideloaded_included_mutates_the_reflection_include_data
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            include_data :if_sideloaded
+            object.blog
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+
+        # Assert
+        assert_respond_to reflection.block, :call
+        assert_equal true, reflection.options.fetch(:include_data_setting)
+        include_slice = {}
+        assert_nil reflection.value(serializer_instance, include_slice)
+        assert_equal :if_sideloaded, reflection.options.fetch(:include_data_setting)
+      end
+
+      def test_reflection_value_block_with_include_data_if_sideloaded_excluded_mutates_the_reflection_include_data
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            include_data :if_sideloaded
+            object.blog
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+
+        # Assert
+        assert_respond_to reflection.block, :call
+        assert_equal true, reflection.options.fetch(:include_data_setting)
+        include_slice = { blog: :does_not_matter }
+        assert_equal @model.blog, reflection.value(serializer_instance, include_slice)
+        assert_equal :if_sideloaded, reflection.options.fetch(:include_data_setting)
+      end
+
+      def test_reflection_block_with_link_mutates_the_reflection_links
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            link :self, 'no_uri_validation'
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+        assert_equal @empty_links, reflection.options.fetch(:links)
+
+        # Build Association
+        association = reflection.build_association(serializer_instance, @instance_options)
+        assert_equal @expected_links, association.links
+        assert_equal @expected_links, reflection.options.fetch(:links)
+      end
+
+      def test_reflection_block_with_link_block_mutates_the_reflection_links
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            link :self do
+              'no_uri_validation'
+            end
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+        assert_equal @empty_links, reflection.options.fetch(:links)
+
+        # Build Association
+        association = reflection.build_association(serializer_instance, @instance_options)
+        # Assert before instance_eval link
+        link = association.links.fetch(:self)
+        assert_respond_to link, :call
+
+        # Assert after instance_eval link
+        assert_equal @expected_links.fetch(:self), reflection.instance_eval(&link)
+        assert_respond_to reflection.options.fetch(:links).fetch(:self), :call
+      end
+
+      def test_reflection_block_with_meta_mutates_the_reflection_meta
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            meta(id: object.blog.id)
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+        assert_nil reflection.options.fetch(:meta)
+
+        # Build Association
+        association = reflection.build_association(serializer_instance, @instance_options)
+        assert_equal @expected_meta, association.meta
+        assert_equal @expected_meta, reflection.options.fetch(:meta)
+      end
+
+      def test_reflection_block_with_meta_block_mutates_the_reflection_meta
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            meta do
+              { id: object.blog.id }
+            end
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+        assert_nil reflection.options.fetch(:meta)
+
+        # Build Association
+        association = reflection.build_association(serializer_instance, @instance_options)
+        # Assert before instance_eval meta
+        assert_respond_to association.meta, :call
+        assert_respond_to reflection.options.fetch(:meta), :call
+
+        # Assert after instance_eval meta
+        assert_equal @expected_meta, reflection.instance_eval(&association.meta)
+        assert_respond_to reflection.options.fetch(:meta), :call
+        assert_respond_to association.meta, :call
+      end
+
+      # rubocop:disable Metrics/AbcSize
+      def test_reflection_block_with_meta_in_link_block_mutates_the_reflection_meta
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            link :self do
+              meta(id: object.blog.id)
+              'no_uri_validation'
+            end
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+        assert_nil reflection.options.fetch(:meta)
+        assert_equal @empty_links, reflection.options.fetch(:links)
+
+        # Build Association
+        association = reflection.build_association(serializer_instance, @instance_options)
+        # Assert before instance_eval link meta
+        assert_nil association.meta
+        assert_nil reflection.options.fetch(:meta)
+
+        link = association.links.fetch(:self)
+        assert_respond_to link, :call
+        assert_respond_to reflection.options.fetch(:links).fetch(:self), :call
+        assert_nil reflection.options.fetch(:meta)
+
+        # Assert after instance_eval link
+        assert_equal 'no_uri_validation', reflection.instance_eval(&link)
+        assert_equal @expected_meta, reflection.options.fetch(:meta)
+        assert_nil association.meta
+      end
+      # rubocop:enable Metrics/AbcSize
+
+      # rubocop:disable Metrics/AbcSize
+      def test_reflection_block_with_meta_block_in_link_block_mutates_the_reflection_meta
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            link :self do
+              meta do
+                { id: object.blog.id }
+              end
+              'no_uri_validation'
+            end
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+        assert_nil reflection.options.fetch(:meta)
+
+        # Build Association
+        association = reflection.build_association(serializer_instance, @instance_options)
+        assert_nil association.meta
+        assert_nil reflection.options.fetch(:meta)
+
+        # Assert before instance_eval link
+        link = association.links.fetch(:self)
+        assert_nil reflection.options.fetch(:meta)
+        assert_respond_to link, :call
+        assert_respond_to association.links.fetch(:self), :call
+
+        # Assert after instance_eval link
+        assert_equal 'no_uri_validation', reflection.instance_eval(&link)
+        assert_respond_to association.links.fetch(:self), :call
+        # Assert before instance_eval link meta
+        assert_respond_to reflection.options.fetch(:meta), :call
+        assert_nil association.meta
+
+        # Assert after instance_eval link meta
+        assert_equal @expected_meta, reflection.instance_eval(&reflection.options.fetch(:meta))
+        assert_nil association.meta
+      end
+      # rubocop:enable Metrics/AbcSize
+
+      def test_no_href_in_vanilla_reflection
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            link :self do
+              href 'no_uri_validation'
+            end
+          end
+        end
+        serializer_instance = serializer_class.new(@model, @instance_options)
+
+        # Get Reflection
+        reflection = serializer_class._reflections.fetch(:blog)
+        assert_equal @empty_links, reflection.options.fetch(:links)
+
+        # Build Association
+        association = reflection.build_association(serializer_instance, @instance_options)
+        # Assert before instance_eval link
+        link = association.links.fetch(:self)
+        assert_respond_to link, :call
+
+        # Assert after instance_eval link
+        exception = assert_raise(NoMethodError) do
+          reflection.instance_eval(&link)
+        end
+        assert_match(/undefined method `href'/, exception.message)
+      end
+
+      # rubocop:disable Metrics/AbcSize
+      def test_mutating_reflection_block_is_not_thread_safe
+        serializer_class = Class.new(ActiveModel::Serializer) do
+          has_one :blog do
+            meta(id: object.blog.id)
+          end
+        end
+        model1_meta = @expected_meta
+        # Evaluate reflection meta for model with id 1
+        serializer_instance = serializer_class.new(@model, @instance_options)
+        reflection = serializer_class._reflections.fetch(:blog)
+        assert_nil reflection.options.fetch(:meta)
+        association = reflection.build_association(serializer_instance, @instance_options)
+        assert_equal model1_meta, association.meta
+        assert_equal model1_meta, reflection.options.fetch(:meta)
+
+        model2_meta = @expected_meta.merge(id: 2)
+        # Evaluate reflection meta for model with id 2
+        @model.blog.id = 2
+        assert_equal 2, @model.blog.id # sanity check
+        serializer_instance = serializer_class.new(@model, @instance_options)
+        reflection = serializer_class._reflections.fetch(:blog)
+
+        # WARN: Thread-safety issue
+        # Before the reflection is evaluated, it has the value from the previous evaluation
+        assert_equal model1_meta, reflection.options.fetch(:meta)
+
+        association = reflection.build_association(serializer_instance, @instance_options)
+        assert_equal model2_meta, association.meta
+        assert_equal model2_meta, reflection.options.fetch(:meta)
+      end
+      # rubocop:enable Metrics/AbcSize
+    end
+  end
+end