Test CachedSerializer#fragment_cached?

CHANGELOG.md

@@ -7,6 +7,8 @@ Features:
   relationship-level links and meta attributes. (@beauby)
 - [#1340](https://github.com/rails-api/active_model_serializers/pull/1340) Add support for resource-level meta. (@beauby)
 Fixes:
+- [#1477](https://github.com/rails-api/active_model_serializers/pull/1477) Fix `fragment_cached?`
+  method to check if caching (@bdmac)
 - [#1501](https://github.com/rails-api/active_model_serializers/pull/1501) Adds tests for SerializableResource::use_adapter?,doc typos (@domitian)
 - [#1488](https://github.com/rails-api/active_model_serializers/pull/1488) Require ActiveSupport's string inflections (@nate00)
 Misc:

test/serializers/cached_serializer_test.rb

@@ -0,0 +1,82 @@
+require 'test_helper'
+module ActiveModel
+  class Serializer
+    module Adapter
+      class CachedSerializerTest < ActiveSupport::TestCase
+        def test_cached_false_without_cache_store
+          cached_serializer = build do |serializer|
+            serializer._cache = nil
+          end
+          refute cached_serializer.cached?
+        end
+
+        def test_cached_true_with_cache_store_and_without_cache_only_and_cache_except
+          cached_serializer = build do |serializer|
+            serializer._cache = Object
+          end
+          assert cached_serializer.cached?
+        end
+
+        def test_cached_false_with_cache_store_and_with_cache_only
+          cached_serializer = build do |serializer|
+            serializer._cache = Object
+            serializer._cache_only = [:name]
+          end
+          refute cached_serializer.cached?
+        end
+
+        def test_cached_false_with_cache_store_and_with_cache_except
+          cached_serializer = build do |serializer|
+            serializer._cache = Object
+            serializer._cache_except = [:content]
+          end
+          refute cached_serializer.cached?
+        end
+
+        def test_fragment_cached_false_without_cache_store
+          cached_serializer = build do |serializer|
+            serializer._cache = nil
+            serializer._cache_only = [:name]
+          end
+          refute cached_serializer.fragment_cached?
+        end
+
+        def test_fragment_cached_true_with_cache_store_and_cache_only
+          cached_serializer = build do |serializer|
+            serializer._cache = Object
+            serializer._cache_only = [:name]
+          end
+          assert cached_serializer.fragment_cached?
+        end
+
+        def test_fragment_cached_true_with_cache_store_and_cache_except
+          cached_serializer = build do |serializer|
+            serializer._cache = Object
+            serializer._cache_except = [:content]
+          end
+          assert cached_serializer.fragment_cached?
+        end
+
+        def test_fragment_cached_false_with_cache_store_and_cache_except_and_cache_only
+          cached_serializer = build do |serializer|
+            serializer._cache = Object
+            serializer._cache_except = [:content]
+            serializer._cache_only = [:name]
+          end
+          refute cached_serializer.fragment_cached?
+        end
+
+        private
+
+        def build
+          serializer = Class.new(ActiveModel::Serializer)
+          serializer._cache_key = nil
+          serializer._cache_options = nil
+          yield serializer if block_given?
+          serializer_instance = serializer.new(Object)
+          ActiveModel::Serializer::Adapter::CachedSerializer.new(serializer_instance)
+        end
+      end
+    end
+  end
+end