Fix MT6 assert_nil warnings

test/serializers/caching_configuration_test_isolated.rb

@@ -69,9 +69,9 @@ class CachingConfigurationTest < ActiveSupport::TestCase
     end
 
     test 'the non-cached serializer cache_store is nil' do
-      assert_equal nil, @non_cached_serializer._cache
-      assert_equal nil, @non_cached_serializer.cache_store
-      assert_equal nil, @non_cached_serializer._cache
+      assert_nil @non_cached_serializer._cache
+      assert_nil @non_cached_serializer.cache_store
+      assert_nil @non_cached_serializer._cache
     end
 
     test 'the non-cached serializer does not have cache_enabled?' do
@@ -136,9 +136,9 @@ class CachingConfigurationTest < ActiveSupport::TestCase
     end
 
     test 'the non-cached serializer cache_store is nil' do
-      assert_equal nil, @non_cached_serializer._cache
-      assert_equal nil, @non_cached_serializer.cache_store
-      assert_equal nil, @non_cached_serializer._cache
+      assert_nil @non_cached_serializer._cache
+      assert_nil @non_cached_serializer.cache_store
+      assert_nil @non_cached_serializer._cache
     end
 
     test 'the non-cached serializer does not have cache_enabled?' do

test/serializers/serializer_for_test.rb

@@ -59,7 +59,7 @@ module ActiveModel
 
         def test_serializer_for_non_ams_serializer
           serializer = ActiveModel::Serializer.serializer_for(@tweet)
-          assert_equal nil, serializer
+          assert_nil serializer
         end
 
         def test_serializer_for_existing_serializer
@@ -71,12 +71,12 @@ module ActiveModel
           serializer = with_serializer_lookup_disabled do
             ActiveModel::Serializer.serializer_for(@profile)
           end
-          assert_equal nil, serializer
+          assert_nil serializer
         end
 
         def test_serializer_for_not_existing_serializer
           serializer = ActiveModel::Serializer.serializer_for(@model)
-          assert_equal nil, serializer
+          assert_nil serializer
         end
 
         def test_serializer_inherited_serializer
@@ -88,7 +88,7 @@ module ActiveModel
           serializer = with_serializer_lookup_disabled do
             ActiveModel::Serializer.serializer_for(@my_profile)
           end
-          assert_equal nil, serializer
+          assert_nil serializer
         end
 
         def test_serializer_custom_serializer
@@ -114,7 +114,7 @@ module ActiveModel
           serializer = with_serializer_lookup_disabled do
             ActiveModel::Serializer.serializer_for(post)
           end
-          assert_equal nil, serializer
+          assert_nil serializer
         end
 
         def test_serializer_for_nested_resource
@@ -128,7 +128,7 @@ module ActiveModel
           serializer = with_serializer_lookup_disabled do
             ResourceNamespace::PostSerializer.serializer_for(comment)
           end
-          assert_equal nil, serializer
+          assert_nil serializer
         end
       end
     end