Restore backwards compatibility broken in 4.3.0 (#51)

Fixes #50

lib/modis.rb

@@ -18,11 +18,14 @@
 require 'modis/model'
 
 module Modis
-  @mutex = Mutex.new
   class << self
     attr_writer :connection_pool_size, :connection_pool_timeout,
                 :connection_pools
 
+    def mutex
+      @mutex ||= Mutex.new
+    end
+
     def redis_options
       @redis_options ||= { default: {} }
     end
@@ -31,7 +34,20 @@ def redis_options=(options)
       if options.is_a?(Hash) && options.values.first.is_a?(Hash)
         @redis_options = options.transform_values(&:dup)
       else
-        @redis_options[:default] = options
+        redis_options[:default] = options
+      end
+    end
+
+    def reset!
+      connection_pools.each do |key, _|
+        with_connection(key) do |connection|
+          keys = connection.keys "#{config.namespace}:*"
+          connection.del(*keys) unless keys.empty?
+        end
+      end
+      instance_variables.each do |var|
+        instance_variable_set(var, nil)
+        remove_instance_variable(var)
       end
     end
 
@@ -49,7 +65,7 @@ def connection_pools
 
     def connection_pool(pool_name = :default)
       connection_pools[pool_name] ||= begin
-        @mutex.synchronize do
+        mutex.synchronize do
           ConnectionPool.new(
             size: connection_pool_size,
             timeout: connection_pool_timeout

lib/modis/configuration.rb

@@ -9,8 +9,8 @@ class Configuration < Struct.new(:namespace)
   end
 
   class << self
-    attr_reader :config
+    def config
+      @config ||= Configuration.new
+    end
   end
-
-  @config = Configuration.new
 end

spec/multi_redis_spec.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'spec_helper'
+
 module MultiRedisSpec
   class DefaultUserModel
     include Modis::Model

spec/spec_helper.rb

@@ -14,18 +14,12 @@
 
 Redis.raise_deprecations = true if Gem.loaded_specs['redis'].version >= Gem::Version.new('4.6.0')
 
-Modis.configure do |config|
-  config.namespace = 'modis'
-end
-
 RSpec.configure do |config|
   config.after :each do
     RSpec::Mocks.space.proxy_for(Modis).reset
-    Modis.connection_pools.each do |key, _|
-      Modis.with_connection(key) do |connection|
-        keys = connection.keys "#{Modis.config.namespace}:*"
-        connection.del(*keys) unless keys.empty?
-      end
+    Modis.reset!
+    Modis.configure do |modis_config|
+      modis_config.namespace = 'modis'
     end
   end
 end