Implement configurable storage backend (#242)

* Implement configurable storage backend

* Refactor `Configuration` class and its usage

* Update tests

* Fix flake test

lib/rails-settings-cached.rb

@@ -10,6 +10,7 @@
 require_relative "rails-settings/fields/string"
 
 require_relative "rails-settings/base"
+require_relative "rails-settings/configuration"
 require_relative "rails-settings/request_cache"
 require_relative "rails-settings/middleware"
 require_relative "rails-settings/railtie"

lib/rails-settings/base.rb

@@ -33,7 +33,7 @@ def clear_cache
     class << self
       def clear_cache
         RequestCache.reset
-        Rails.cache.delete(cache_key)
+        cache_storage.delete(cache_key)
       end
 
       def field(key, **opts)
@@ -127,13 +127,17 @@ def rails_initialized?
       end
 
       def _all_settings
-        RequestCache.all_settings ||= Rails.cache.fetch(cache_key, expires_in: 1.week) do
+        RequestCache.all_settings ||= cache_storage.fetch(cache_key, expires_in: 1.week) do
           vars = unscoped.select("var, value")
           result = {}
           vars.each { |record| result[record.var] = record.value }
           result.with_indifferent_access
         end
       end
+
+      def cache_storage
+        RailsSettings.config.cache_storage
+      end
     end
   end
 end

lib/rails-settings/configuration.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module RailsSettings
+  class Configuration
+    # Caching storage backend.
+    # Default: `Rails.cache`
+    attr_accessor :cache_storage
+  end
+
+  class << self
+    def config
+      return @config if defined?(@config)
+
+      @config = Configuration.new
+      @config.cache_storage = Rails.cache
+      @config
+    end
+
+    def configure(&block)
+      config.instance_exec(&block)
+    end
+  end
+end

test/base_test.rb

@@ -424,4 +424,27 @@ class NewSetting < RailsSettings::Base
     assert_equal %(SELECT "settings".* FROM "settings" WHERE (var like 'readonly_%')), Setting.by_prefix("readonly_").to_sql
     assert_equal "foo", Setting.by_prefix("readonly_").foo
   end
+
+  class CustomCacheStorageTest < ActiveSupport::TestCase
+    setup do
+      RailsSettings.configure do
+        self.cache_storage = ActiveSupport::Cache.lookup_store(:dummy_store)
+      end
+    end
+
+    teardown do
+      RailsSettings.configure do
+        self.cache_storage = Rails.cache
+      end
+    end
+
+    test "uses expected cached storage" do
+      Setting.user_limits = 42
+
+      assert_equal Setting.user_limits, 42
+      assert RailsSettings.config.cache_storage.data.keys.any? do |key|
+        key.start_with?("rails-settings-cached")
+      end
+    end
+  end
 end

test/configuration_test.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class ConfigurationTest < ActiveSupport::TestCase
+  test "configuration" do
+    RailsSettings.configure do
+      self.cache_storage = ActiveSupport::Cache.lookup_store(:dummy_store)
+    end
+
+    assert RailsSettings.config.cache_storage.instance_of? ActiveSupport::Cache::DummyStore
+  end
+end

test/dummy/lib/active_support/cache/dummy_store.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+module ActiveSupport
+  module Cache
+    class DummyStore < Store
+      attr_reader :data
+
+      def initialize(options = {})
+        super(options)
+
+        @data = {}
+      end
+
+      def read_entry(key, **options)
+        data[key]
+      end
+
+      def write_entry(key, value, **options)
+        data[key] = value
+      end
+
+      def delete_entry(key, **options)
+        data.delete(key)
+      end
+    end
+  end
+end