NullStore implementation

lib/any_cache/adapters.rb

@@ -36,7 +36,12 @@ def build(driver)
       when ActiveSupportDalliStore.supported_driver?(driver)      then ActiveSupportDalliStore.new(driver)
       when Delegator.supported_driver?(driver)                    then Delegator.new(driver)
       else
-        raise AnyCache::UnsupportedDriverError
+        # Explicit check because NullStore isn't loaded by default
+        if defined?(::AnyCache::Adapters::NullStore) && ::AnyCache::Adapters::NullStore.supported_driver?(driver)
+          NullStore.new(driver)
+        else
+          raise AnyCache::UnsupportedDriverError
+        end
       end
     end
     # rubocop:enable Metrics/LineLength, Metrics/AbcSize

lib/any_cache/adapters/null_store.rb

@@ -0,0 +1,191 @@
+# frozen_string_literal: true
+
+module AnyCache::Adapters
+  # @api private
+  # @since 0.1.0
+  class NullStore
+    # @since 0.1.0
+    extend Forwardable
+    # @since 0.4.0
+    include AnyCache::Dumper::InterfaceAccessMixin
+
+    class << self
+      # @param driver [Object]
+      # @return [Boolean]
+      #
+      # @api private
+      # @since 0.1.0
+      def supported_driver?(driver)
+        driver.nil?
+      end
+    end
+
+    # @return [Object]
+    #
+    # @api private
+    # @since 0.1.0
+    attr_reader :driver
+
+    # @param driver [Object]
+    # @return [void]
+    #
+    # @api private
+    # @since 0.1.0
+    def initialize(driver)
+      @driver = driver
+    end
+
+    # @param key [String]
+    # @param options [Hash]
+    # @return [Object]
+    #
+    # @api private
+    # @since 0.1.0
+    def read(key, **options)
+      # no-op
+    end
+
+    # @param keys [Array<String>]
+    # @param options [Hash]
+    # @return [Hash]
+    #
+    # @api private
+    # @since 0.3.0
+    def read_multi(*keys, **options)
+      # no-op
+    end
+
+    # @param key [String]
+    # @param value [Object]
+    # @param options [Hash]
+    # @return [void]
+    #
+    # @api private
+    # @sinc 0.1.0
+    def write(key, value, **options)
+      # no-op
+    end
+
+    # @param entries [Hash]
+    # @param options [Hash]
+    # @return [void]
+    #
+    # @api private
+    # @since 0.3.0
+    def write_multi(entries, **options)
+      # no-op
+    end
+
+    # @param key [String]
+    # @param options [Hash]
+    # @param fallback [Proc]
+    # @return [Object]
+    #
+    # @api private
+    # @since 0.2.0
+    def fetch(key, **options, &fallback)
+      # no-op
+    end
+
+    # @param keys [Array<String>]
+    # @param options [Hash]
+    # @param fallback [Proc]
+    # @return [Hash]
+    #
+    # @api private
+    # @since 0.3.0
+    def fetch_multi(*keys, **options, &fallback)
+      # no-op
+    end
+
+    # @param key [String]
+    # @param options [Hash]
+    # @return [void]
+    #
+    # @api private
+    # @since 0.1.0
+    def delete(key, **options)
+      # no-op
+    end
+
+    # @param pattern [Regexp, String, Object]
+    # @param options [Hash]
+    # @return [void]
+    #
+    # @api private
+    # @since 0.3.0
+    def delete_matched(pattern, **options)
+      # no-op
+    end
+
+    # @param key [String]
+    # @param value [Integer, Float]
+    # @param options [Hash]
+    # @return [Integer, Float]
+    #
+    # @api private
+    # @sinc 0.1.0
+    def increment(key, value, **options)
+      value
+    end
+
+    # @param key [String]
+    # @param value [Integer, Float]
+    # @param options [Hash]
+    # @return [Integer, Float]
+    #
+    # @api private
+    # @since 0.1.0
+    def decrement(key, value, **options)
+      value
+    end
+
+    # @param key [String]
+    # @option expires_in [Integer]
+    # @return [void]
+    #
+    # @api private
+    # @since 0.1.0
+    def expire(key, expires_in:)
+      # no-op
+    end
+
+    # @param key [String]
+    # @param options [Hash]
+    # @return [void]
+    #
+    # @api private
+    # @since 0.1.0
+    def persist(key, **options)
+      # no-op
+    end
+
+    # @param options [Hash]
+    # @return [void]
+    #
+    # @api private
+    # @since 0.1.0
+    def clear(**options)
+      # no-op
+    end
+
+    # @param options [Hash]
+    # @return [void]
+    #
+    # @api private
+    # @since 0.4.0
+    def cleanup(**options)
+      # no-op
+    end
+
+    # @param key [String]
+    # @param options [Hash]
+    # @return [Boolean]
+    #
+    # @api private
+    # @since 0.2.0
+    def exist?(key, **options)
+      false
+    end
+  end
+end

spec/lib/any_cache/adapters/null_store_spec.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+describe "::AnyCache::Adapters::NullStore" do
+  it "has a null store if it's been explicitly loaded" do
+    load "any_cache/adapters/null_store.rb"
+
+    expect(AnyCache.build(nil).adapter).to be_instance_of(AnyCache::Adapters::NullStore)
+  end
+
+  it "doesn't load unless it's been explicitly loaded" do
+    AnyCache::Adapters.send(:remove_const, :NullStore) if AnyCache::Adapters.constants.include?(:NullStore)
+
+    expect { AnyCache.build(nil).adapter }.to raise_error(AnyCache::UnsupportedDriverError)
+  end
+end