Allow StripeClient to be configured per instance

This changes allows for each instance of `StripeClient` to have its own
configuration object instead of relying on the global config. Each
instance can be configured to override any global config values
previously set.

lib/stripe.rb

@@ -62,6 +62,8 @@ module Stripe
   class << self
     extend Forwardable
 
+    attr_reader :configuration
+
     # User configurable options
     def_delegators :@configuration, :api_key, :api_key=
     def_delegators :@configuration, :api_version, :api_version=

lib/stripe/connection_manager.rb

@@ -15,8 +15,10 @@ class ConnectionManager
     # by `StripeClient` to determine whether a connection manager should be
     # garbage collected or not.
     attr_reader :last_used
+    attr_reader :config
 
-    def initialize
+    def initialize(config = Stripe.configuration)
+      @config = config
       @active_connections = {}
       @last_used = Util.monotonic_time
 
@@ -117,17 +119,17 @@ def execute_request(method, uri, body: nil, headers: nil, query: nil)
       # reused Go's default for `DefaultTransport`.
       connection.keep_alive_timeout = 30
 
-      connection.open_timeout = Stripe.open_timeout
-      connection.read_timeout = Stripe.read_timeout
+      connection.open_timeout = config.open_timeout
+      connection.read_timeout = config.read_timeout
       if connection.respond_to?(:write_timeout=)
-        connection.write_timeout = Stripe.write_timeout
+        connection.write_timeout = config.write_timeout
       end
 
       connection.use_ssl = uri.scheme == "https"
 
-      if Stripe.verify_ssl_certs
+      if config.verify_ssl_certs
         connection.verify_mode = OpenSSL::SSL::VERIFY_PEER
-        connection.cert_store = Stripe.ca_store
+        connection.cert_store = config.ca_store
       else
         connection.verify_mode = OpenSSL::SSL::VERIFY_NONE
         warn_ssl_verify_none
@@ -141,10 +143,10 @@ def execute_request(method, uri, body: nil, headers: nil, query: nil)
     # out those pieces to make passing them into a new connection a little less
     # ugly.
     private def proxy_parts
-      if Stripe.proxy.nil?
+      if config.proxy.nil?
         [nil, nil, nil, nil]
       else
-        u = URI.parse(Stripe.proxy)
+        u = URI.parse(config.proxy)
         [u.host, u.port, u.user, u.password]
       end
     end

lib/stripe/oauth.rb

@@ -7,8 +7,8 @@ module OAuthOperations
 
       def self.execute_resource_request(method, url, params, opts)
         opts = Util.normalize_opts(opts)
-        opts[:client] ||= StripeClient.active_client
-        opts[:api_base] ||= Stripe.connect_base
+        opts[:client] ||= opts[:client] || StripeClient.active_client
+        opts[:api_base] ||= opts[:client].config.connect_base
 
         super(method, url, params, opts)
       end
@@ -29,7 +29,8 @@ def self.get_client_id(params = {})
     end
 
     def self.authorize_url(params = {}, opts = {})
-      base = opts[:connect_base] || Stripe.connect_base
+      client = opts[:client] || StripeClient.active_client
+      base = opts[:connect_base] || client.config.connect_base
 
       path = "/oauth/authorize"
       path = "/express" + path if opts[:express]

lib/stripe/resources/account.rb

@@ -45,12 +45,8 @@ def resource_url
     end
 
     # @override To make id optional
-    def self.retrieve(id = ARGUMENT_NOT_PROVIDED, opts = {})
-      id = if id.equal?(ARGUMENT_NOT_PROVIDED)
-             nil
-           else
-             Util.check_string_argument!(id)
-           end
+    def self.retrieve(id = nil, opts = {})
+      Util.check_string_argument!(id) if id
 
       # Account used to be a singleton, where this method's signature was
       # `(opts={})`. For the sake of not breaking folks who pass in an OAuth
@@ -136,11 +132,10 @@ def deauthorize(client_id = nil, opts = {})
         client_id: client_id,
         stripe_user_id: id,
       }
+      opts = @opts.merge(Util.normalize_opts(opts))
       OAuth.deauthorize(params, opts)
     end
 
-    ARGUMENT_NOT_PROVIDED = Object.new
-
     private def serialize_additional_owners(legal_entity, additional_owners)
       original_value =
         legal_entity

lib/stripe/resources/file.rb

@@ -25,8 +25,9 @@ def self.create(params = {}, opts = {})
         end
       end
 
+      config = opts[:client]&.config || Stripe.configuration
       opts = {
-        api_base: Stripe.uploads_base,
+        api_base: config.uploads_base,
         content_type: MultipartEncoder::MULTIPART_FORM_DATA,
       }.merge(Util.normalize_opts(opts))
       super