Need to teardown the dynamically added method

test/action_controller/serialization_scope_name_test.rb

@@ -1,6 +1,17 @@
 require 'test_helper'
 
 module SerializationScopeTesting
+  def self.undef_serializer_dynamic_scope_methods
+    [PostSerializer, PostViewContextSerializer]. each do |serializer_class|
+      instance_method_cache = serializer_class.instance_variable_get(:@_serializer_instance_methods)
+      class_method_cache    = serializer_class.class_variable_get(:@@_serializer_instance_methods)[serializer_class]
+      [:view_context, :current_user].each do |scope_method|
+        serializer_class.send(:undef_method, scope_method) if serializer_class.method_defined?(scope_method)
+        instance_method_cache && instance_method_cache.delete(scope_method)
+        class_method_cache && class_method_cache.delete(scope_method)
+      end
+    end
+  end
   class User < ActiveModelSerializers::Model
     attr_accessor :id, :name, :admin
     def admin?
@@ -70,6 +81,10 @@ def comments
   class DefaultScopeTest < ActionController::TestCase
     tests PostTestController
 
+    teardown do
+      SerializationScopeTesting.undef_serializer_dynamic_scope_methods
+    end
+
     def test_default_serialization_scope
       assert_equal :current_user, @controller._serialization_scope
     end
@@ -120,6 +135,10 @@ def serializer
     end
     tests PostViewContextTestController
 
+    teardown do
+      SerializationScopeTesting.undef_serializer_dynamic_scope_methods
+    end
+
     def test_defined_serialization_scope
       assert_equal :view_context, @controller._serialization_scope
     end
@@ -187,6 +206,10 @@ def new_post
     end
     tests PostViewContextTestController
 
+    teardown do
+      SerializationScopeTesting.undef_serializer_dynamic_scope_methods
+    end
+
     def test_nil_serialization_scope
       assert_nil @controller._serialization_scope
     end
@@ -196,14 +219,8 @@ def test_nil_serialization_scope_object
     end
 
     def test_nil_scope
-      if Rails.version.start_with?('4.0')
-        exception_class = NoMethodError
-        exception_matcher = 'admin?'
-      else
-        exception_class = NameError
-        exception_matcher = /admin|current_user/
-      end
-      exception = assert_raises(exception_class) do
+      exception_matcher = /current_user/
+      exception = assert_raises(NameError) do
         get :render_post_with_no_scope
       end
       assert_match exception_matcher, exception.message
@@ -225,18 +242,11 @@ def test_serialization_scope_is_and_nil_scope_passed_in_current_user
     end
 
     def test_serialization_scope_is_nil_and_scope_passed_in_current_user_without_scope_name
-      get :render_post_with_passed_in_scope_without_scope_name
-      expected_json = {
-        post: {
-          id: 4,
-          title: 'Title',
-          body: "The 'scope' is the 'current_user': true",
-          comments: [
-            { id: 2, body: 'Scoped' }
-          ]
-        }
-      }.to_json
-      assert_equal expected_json, @response.body
+      exception_matcher = /current_user/
+      exception = assert_raises(NameError) do
+        get :render_post_with_passed_in_scope_without_scope_name
+      end
+      assert_match exception_matcher, exception.message
     end
   end
 end