Specs for custom cache clients

Rakefile

@@ -2,6 +2,16 @@
 
 require 'bundler/gem_tasks'
 require 'rspec/core/rake_task'
+require 'rubocop'
+require 'rubocop-rspec'
+require 'rubocop/rake_task'
+
+RuboCop::RakeTask.new(:rubocop) do |t|
+  config_path = File.expand_path(File.join('.rubocop.yml'), __dir__)
+
+  t.options = ['--config', config_path]
+  t.requires << 'rubocop-rspec'
+end
 
 RSpec::Core::RakeTask.new(:rspec)
 

lib/any_cache.rb

@@ -8,6 +8,7 @@
 # @since 0.1.0
 class AnyCache
   require_relative 'any_cache/version'
+  require_relative 'any_cache/error'
   require_relative 'any_cache/drivers'
   require_relative 'any_cache/adapters'
 

lib/any_cache/adapters.rb

@@ -18,7 +18,7 @@ class << self
     # @param driver [Object]
     # @return [AnyCache::Adapters::Basic]
     #
-    # @raise [AnyCache::UnsupportedCacheDriverError]
+    # @raise [AnyCache::UnsupportedDriverError]
     #
     # @api private
     # @since 0.1.0
@@ -34,7 +34,7 @@ def build(driver)
       when ActiveSupportMemCacheStore.supported_driver?(driver)   then ActiveSupportMemCacheStore.new(driver)
       when Delegator.supported_driver?(driver)                    then Delegator.new(driver)
       else
-        raise AnyCache::UnsupportedCacheDriverError
+        raise AnyCache::UnsupportedDriverError
       end
     end
     # rubocop:enable Metrics/LineLength

spec/features/custom_cache_clients_spec.rb

@@ -0,0 +1,111 @@
+# frozen_string_literal: true
+
+describe 'Custom cache clients' do
+  context 'when custom cache clinet supports all required methods' do
+    let(:custom_client) do
+      Class.new do
+        # rubocop:disable Layout/EmptyLineBetweenDefs
+        def read(key, **); end
+        def write(key, value, **); end
+        def delete(key, **); end
+        def increment(key, value, **); end
+        def decrement(key, value, **); end
+        def expire(key, **); end
+        def persist(key, **); end
+        def clear(key, **); end
+        def exist?(key, **); end
+        # rubocop:enable Layout/EmptyLineBetweenDefs
+      end.new
+    end
+
+    let(:dumb_client) do
+      # rubocop:disable Layout/EmptyLineBetweenDefs
+      Class.new do
+        def read; end
+        def write; end
+        def delete; end
+        def increment; end
+        def decrement; end
+        def expire; end
+        def persist; end
+        def clear; end
+        def exist?; end
+      end.new
+      # rubocop:enable Layout/EmptyLineBetweenDefs
+    end
+
+    specify 'returns AnyCache instance' do
+      expect(AnyCache.build(custom_client)).to be_a(AnyCache)
+    end
+
+    specify 'requires only a delegation' do
+      expect(AnyCache.build(dumb_client)).to be_a(AnyCache)
+    end
+
+    %i[
+      read
+      delete
+      expire
+      persist
+      clear
+      exist?
+    ].each do |operation|
+      specify "AnyCache instance delegates :#{operation} operation to the custom client" do
+        cache_store = AnyCache.build(custom_client)
+
+        entry_key      = SecureRandom.hex
+        method_options = { SecureRandom.hex.to_sym => SecureRandom.hex }
+
+        expect(custom_client).to receive(operation).with(entry_key, method_options)
+        cache_store.send(operation, entry_key, **method_options)
+      end
+    end
+
+    %i[
+      write
+      increment
+      decrement
+    ].each do |operation|
+      specify "AnyCache instance delegates :#{operation} operation to the custom client" do
+        cache_store = AnyCache.build(custom_client)
+
+        entry_key      = SecureRandom.hex
+        method_value   = SecureRandom.hex
+        method_options = { SecureRandom.hex.to_sym => SecureRandom.hex }
+
+        expect(custom_client).to receive(operation).with(entry_key, method_value, method_options)
+        cache_store.send(operation, entry_key, method_value, **method_options)
+      end
+    end
+  end
+
+  context 'when custom cache client supports a part of required methods' do
+    let(:required_methods) do
+      %i[
+        read
+        write
+        delete
+        increment
+        decrement
+        expire
+        persist
+        clear
+        exist?
+      ]
+    end
+
+    specify 'fails due to instantiation' do
+      while required_methods.shift
+        incomplete_cache_client = Class.new.tap do |klass|
+          required_methods.each do |required_method|
+            klass.define_method(required_method) {}
+          end
+        end.new
+
+        expect do
+          AnyCache.build(incomplete_cache_client)
+        end.to raise_error(AnyCache::UnsupportedDriverError)
+      end
+    end
+  end
+end