From 863da48398e3c003556bc4bcde7c165f382ad025 Mon Sep 17 00:00:00 2001
From: Brandur <brandur@brandur.org>
Date: Thu, 10 May 2018 14:56:14 -0700
Subject: [PATCH] Add `frozen_string_literal` to every file and enforce Rubocop
 rule

Adds the magic `frozen_string_literal: true` comment to every file and
enables a Rubocop rule to make sure that it's always going to be there
going forward as well.

See here for more background [1], but the basic idea is that unlike many
other languages, static strings in code are mutable by default. This has
since been acknowledged as not a particularly good idea, and the
intention is to rectify the mistake when Ruby 3 comes out, where all
string literals will be frozen. The `frozen_string_literal` magic
comment was introduced in Ruby 2.3 as a way of easing the transition,
and allows libraries and projects to freeze their literals in advance.

I don't think this is breaking in any way: it's possible that users
might've been pulling out one of are literals somehow and mutating it,
but that would probably not have been useful for anything and would
certainly not be recommended, so I'm quite comfortable pushing this
change through as a minor version.

As discussed in #641.

[1] https://stackoverflow.com/a/37799399
---
 .rubocop.yml                                             | 3 +++
 Gemfile                                                  | 2 ++
 Rakefile                                                 | 2 ++
 bin/stripe-console                                       | 2 ++
 lib/stripe.rb                                            | 2 ++
 lib/stripe/account.rb                                    | 2 ++
 lib/stripe/alipay_account.rb                             | 2 ++
 lib/stripe/api_operations/create.rb                      | 2 ++
 lib/stripe/api_operations/delete.rb                      | 2 ++
 lib/stripe/api_operations/list.rb                        | 2 ++
 lib/stripe/api_operations/nested_resource.rb             | 2 ++
 lib/stripe/api_operations/request.rb                     | 2 ++
 lib/stripe/api_operations/save.rb                        | 2 ++
 lib/stripe/api_resource.rb                               | 2 ++
 lib/stripe/apple_pay_domain.rb                           | 2 ++
 lib/stripe/application_fee.rb                            | 2 ++
 lib/stripe/application_fee_refund.rb                     | 2 ++
 lib/stripe/balance.rb                                    | 2 ++
 lib/stripe/balance_transaction.rb                        | 2 ++
 lib/stripe/bank_account.rb                               | 2 ++
 lib/stripe/bitcoin_receiver.rb                           | 2 ++
 lib/stripe/bitcoin_transaction.rb                        | 2 ++
 lib/stripe/card.rb                                       | 2 ++
 lib/stripe/charge.rb                                     | 2 ++
 lib/stripe/country_spec.rb                               | 2 ++
 lib/stripe/coupon.rb                                     | 2 ++
 lib/stripe/customer.rb                                   | 2 ++
 lib/stripe/dispute.rb                                    | 2 ++
 lib/stripe/ephemeral_key.rb                              | 2 ++
 lib/stripe/errors.rb                                     | 2 ++
 lib/stripe/event.rb                                      | 2 ++
 lib/stripe/exchange_rate.rb                              | 2 ++
 lib/stripe/file_upload.rb                                | 2 ++
 lib/stripe/invoice.rb                                    | 2 ++
 lib/stripe/invoice_item.rb                               | 2 ++
 lib/stripe/invoice_line_item.rb                          | 2 ++
 lib/stripe/issuer_fraud_record.rb                        | 2 ++
 lib/stripe/list_object.rb                                | 2 ++
 lib/stripe/login_link.rb                                 | 2 ++
 lib/stripe/oauth.rb                                      | 2 ++
 lib/stripe/order.rb                                      | 2 ++
 lib/stripe/order_return.rb                               | 2 ++
 lib/stripe/payout.rb                                     | 2 ++
 lib/stripe/plan.rb                                       | 2 ++
 lib/stripe/product.rb                                    | 2 ++
 lib/stripe/recipient.rb                                  | 2 ++
 lib/stripe/recipient_transfer.rb                         | 2 ++
 lib/stripe/refund.rb                                     | 2 ++
 lib/stripe/reversal.rb                                   | 2 ++
 lib/stripe/singleton_api_resource.rb                     | 2 ++
 lib/stripe/sku.rb                                        | 2 ++
 lib/stripe/source.rb                                     | 2 ++
 lib/stripe/source_transaction.rb                         | 2 ++
 lib/stripe/stripe_client.rb                              | 2 ++
 lib/stripe/stripe_object.rb                              | 2 ++
 lib/stripe/stripe_response.rb                            | 2 ++
 lib/stripe/subscription.rb                               | 2 ++
 lib/stripe/subscription_item.rb                          | 2 ++
 lib/stripe/three_d_secure.rb                             | 2 ++
 lib/stripe/token.rb                                      | 2 ++
 lib/stripe/topup.rb                                      | 2 ++
 lib/stripe/transfer.rb                                   | 2 ++
 lib/stripe/usage_record.rb                               | 2 ++
 lib/stripe/util.rb                                       | 2 ++
 lib/stripe/version.rb                                    | 2 ++
 lib/stripe/webhook.rb                                    | 2 ++
 stripe.gemspec                                           | 2 ++
 test/api_stub_helpers.rb                                 | 1 +
 test/stripe/account_external_accounts_operations_test.rb | 2 ++
 test/stripe/account_login_links_operations_test.rb       | 2 ++
 test/stripe/account_test.rb                              | 2 ++
 test/stripe/alipay_account_test.rb                       | 2 ++
 test/stripe/api_operations_test.rb                       | 2 ++
 test/stripe/api_resource_test.rb                         | 2 ++
 test/stripe/apple_pay_domain_test.rb                     | 2 ++
 test/stripe/application_fee_refund_test.rb               | 2 ++
 test/stripe/application_fee_refunds_operations_test.rb   | 2 ++
 test/stripe/application_fee_test.rb                      | 2 ++
 test/stripe/balance_test.rb                              | 2 ++
 test/stripe/bank_account_test.rb                         | 2 ++
 test/stripe/charge_test.rb                               | 2 ++
 test/stripe/country_spec_test.rb                         | 2 ++
 test/stripe/coupon_test.rb                               | 2 ++
 test/stripe/customer_card_test.rb                        | 2 ++
 test/stripe/customer_sources_operations_test.rb          | 2 ++
 test/stripe/customer_test.rb                             | 2 ++
 test/stripe/dispute_test.rb                              | 2 ++
 test/stripe/ephemeral_key_test.rb                        | 2 ++
 test/stripe/errors_test.rb                               | 2 ++
 test/stripe/exchange_rate_test.rb                        | 2 ++
 test/stripe/file_upload_test.rb                          | 2 ++
 test/stripe/invoice_item_test.rb                         | 2 ++
 test/stripe/invoice_line_item_test.rb                    | 2 ++
 test/stripe/invoice_test.rb                              | 2 ++
 test/stripe/issuer_fraud_record_test.rb                  | 2 ++
 test/stripe/list_object_test.rb                          | 2 ++
 test/stripe/login_link_test.rb                           | 2 ++
 test/stripe/oauth_test.rb                                | 2 ++
 test/stripe/order_return_test.rb                         | 2 ++
 test/stripe/order_test.rb                                | 2 ++
 test/stripe/payout_test.rb                               | 2 ++
 test/stripe/plan_test.rb                                 | 2 ++
 test/stripe/product_test.rb                              | 2 ++
 test/stripe/recipient_test.rb                            | 2 ++
 test/stripe/refund_test.rb                               | 2 ++
 test/stripe/reversal_test.rb                             | 2 ++
 test/stripe/sku_test.rb                                  | 2 ++
 test/stripe/source_test.rb                               | 2 ++
 test/stripe/source_transaction_test.rb                   | 2 ++
 test/stripe/stripe_client_test.rb                        | 2 ++
 test/stripe/stripe_object_test.rb                        | 2 ++
 test/stripe/stripe_response_test.rb                      | 2 ++
 test/stripe/subscription_item_test.rb                    | 2 ++
 test/stripe/subscription_test.rb                         | 2 ++
 test/stripe/three_d_secure_test.rb                       | 2 ++
 test/stripe/topup_test.rb                                | 2 ++
 test/stripe/transfer_reversals_operations_test.rb        | 2 ++
 test/stripe/transfer_test.rb                             | 2 ++
 test/stripe/usage_record_test.rb                         | 2 ++
 test/stripe/util_test.rb                                 | 2 ++
 test/stripe/webhook_test.rb                              | 2 ++
 test/stripe_test.rb                                      | 2 ++
 test/test_data.rb                                        | 2 ++
 test/test_helper.rb                                      | 2 ++
 124 files changed, 248 insertions(+)

diff --git a/.rubocop.yml b/.rubocop.yml
index 8c0f48a7f..031686797 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -13,6 +13,9 @@ Layout/IndentArray:
 Layout/IndentHash:
   EnforcedStyle: consistent
 
+Style/FrozenStringLiteralComment:
+  EnforcedStyle: always
+
 Style/StringLiterals:
   EnforcedStyle: double_quotes
 
diff --git a/Gemfile b/Gemfile
index 808b57053..8d13dd037 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source "https://rubygems.org"
 
 gemspec
diff --git a/Rakefile b/Rakefile
index 495981330..0284c1389 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "rake/testtask"
 require "rubocop/rake_task"
 
diff --git a/bin/stripe-console b/bin/stripe-console
index e7b1cce7e..ecf27d2f2 100755
--- a/bin/stripe-console
+++ b/bin/stripe-console
@@ -1,5 +1,7 @@
 #!/usr/bin/env ruby
 
+# frozen_string_literal: true
+
 require "irb"
 require "irb/completion"
 
diff --git a/lib/stripe.rb b/lib/stripe.rb
index ac70d20ca..e5732d19f 100644
--- a/lib/stripe.rb
+++ b/lib/stripe.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Stripe Ruby bindings
 # API spec at https://stripe.com/docs/api
 require "cgi"
diff --git a/lib/stripe/account.rb b/lib/stripe/account.rb
index 966261bf5..000a06100 100644
--- a/lib/stripe/account.rb
+++ b/lib/stripe/account.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Account < APIResource
     extend Gem::Deprecate
diff --git a/lib/stripe/alipay_account.rb b/lib/stripe/alipay_account.rb
index e0e1ee870..ea92b5692 100644
--- a/lib/stripe/alipay_account.rb
+++ b/lib/stripe/alipay_account.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class AlipayAccount < APIResource
     include Stripe::APIOperations::Save
diff --git a/lib/stripe/api_operations/create.rb b/lib/stripe/api_operations/create.rb
index 1ec29873b..831859e2e 100644
--- a/lib/stripe/api_operations/create.rb
+++ b/lib/stripe/api_operations/create.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     module Create
diff --git a/lib/stripe/api_operations/delete.rb b/lib/stripe/api_operations/delete.rb
index aa047bae2..35571cf19 100644
--- a/lib/stripe/api_operations/delete.rb
+++ b/lib/stripe/api_operations/delete.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     module Delete
diff --git a/lib/stripe/api_operations/list.rb b/lib/stripe/api_operations/list.rb
index 4c46930e6..65c46adc0 100644
--- a/lib/stripe/api_operations/list.rb
+++ b/lib/stripe/api_operations/list.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     module List
diff --git a/lib/stripe/api_operations/nested_resource.rb b/lib/stripe/api_operations/nested_resource.rb
index 36deff3a2..bee575b17 100644
--- a/lib/stripe/api_operations/nested_resource.rb
+++ b/lib/stripe/api_operations/nested_resource.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     # Adds methods to help manipulate a subresource from its parent resource so
diff --git a/lib/stripe/api_operations/request.rb b/lib/stripe/api_operations/request.rb
index 70a6ecc05..cf38b482b 100644
--- a/lib/stripe/api_operations/request.rb
+++ b/lib/stripe/api_operations/request.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     module Request
diff --git a/lib/stripe/api_operations/save.rb b/lib/stripe/api_operations/save.rb
index 77add5cdd..566becbb4 100644
--- a/lib/stripe/api_operations/save.rb
+++ b/lib/stripe/api_operations/save.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     module Save
diff --git a/lib/stripe/api_resource.rb b/lib/stripe/api_resource.rb
index 75b25c4ed..d31d0c463 100644
--- a/lib/stripe/api_resource.rb
+++ b/lib/stripe/api_resource.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class APIResource < StripeObject
     include Stripe::APIOperations::Request
diff --git a/lib/stripe/apple_pay_domain.rb b/lib/stripe/apple_pay_domain.rb
index 21fa53fdf..740f1f10d 100644
--- a/lib/stripe/apple_pay_domain.rb
+++ b/lib/stripe/apple_pay_domain.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   # Domains registered for Apple Pay on the Web
   class ApplePayDomain < APIResource
diff --git a/lib/stripe/application_fee.rb b/lib/stripe/application_fee.rb
index 375f08520..0691a70a4 100644
--- a/lib/stripe/application_fee.rb
+++ b/lib/stripe/application_fee.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class ApplicationFee < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/application_fee_refund.rb b/lib/stripe/application_fee_refund.rb
index 1b29a75ea..27fded1cc 100644
--- a/lib/stripe/application_fee_refund.rb
+++ b/lib/stripe/application_fee_refund.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class ApplicationFeeRefund < APIResource
     include Stripe::APIOperations::Save
diff --git a/lib/stripe/balance.rb b/lib/stripe/balance.rb
index bd1fc6d57..34b9d64e2 100644
--- a/lib/stripe/balance.rb
+++ b/lib/stripe/balance.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Balance < SingletonAPIResource
     OBJECT_NAME = "balance".freeze
diff --git a/lib/stripe/balance_transaction.rb b/lib/stripe/balance_transaction.rb
index 0232c3386..2bc646760 100644
--- a/lib/stripe/balance_transaction.rb
+++ b/lib/stripe/balance_transaction.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class BalanceTransaction < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/bank_account.rb b/lib/stripe/bank_account.rb
index a57ba5b14..53d0688a7 100644
--- a/lib/stripe/bank_account.rb
+++ b/lib/stripe/bank_account.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class BankAccount < APIResource
     include Stripe::APIOperations::Save
diff --git a/lib/stripe/bitcoin_receiver.rb b/lib/stripe/bitcoin_receiver.rb
index b5091f1b8..f9f960f31 100644
--- a/lib/stripe/bitcoin_receiver.rb
+++ b/lib/stripe/bitcoin_receiver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class BitcoinReceiver < APIResource
     # Directly creating or retrieving BitcoinReceivers is deprecated. Please use
diff --git a/lib/stripe/bitcoin_transaction.rb b/lib/stripe/bitcoin_transaction.rb
index 941a30560..966937cb0 100644
--- a/lib/stripe/bitcoin_transaction.rb
+++ b/lib/stripe/bitcoin_transaction.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class BitcoinTransaction < APIResource
     # Directly retrieving BitcoinTransactions is deprecated. Please use the
diff --git a/lib/stripe/card.rb b/lib/stripe/card.rb
index 523e9f5eb..0bd1dc32d 100644
--- a/lib/stripe/card.rb
+++ b/lib/stripe/card.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Card < APIResource
     include Stripe::APIOperations::Save
diff --git a/lib/stripe/charge.rb b/lib/stripe/charge.rb
index eff0a6c65..96ce19d94 100644
--- a/lib/stripe/charge.rb
+++ b/lib/stripe/charge.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Charge < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/country_spec.rb b/lib/stripe/country_spec.rb
index 06bdc2f60..4bae8ffd4 100644
--- a/lib/stripe/country_spec.rb
+++ b/lib/stripe/country_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class CountrySpec < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/coupon.rb b/lib/stripe/coupon.rb
index 5439abe51..767500e32 100644
--- a/lib/stripe/coupon.rb
+++ b/lib/stripe/coupon.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Coupon < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/customer.rb b/lib/stripe/customer.rb
index 21bce5bae..c37033901 100644
--- a/lib/stripe/customer.rb
+++ b/lib/stripe/customer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Customer < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/dispute.rb b/lib/stripe/dispute.rb
index abfbd1ae3..5b7f2892f 100644
--- a/lib/stripe/dispute.rb
+++ b/lib/stripe/dispute.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Dispute < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/ephemeral_key.rb b/lib/stripe/ephemeral_key.rb
index 16431f760..96c18493c 100644
--- a/lib/stripe/ephemeral_key.rb
+++ b/lib/stripe/ephemeral_key.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class EphemeralKey < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/errors.rb b/lib/stripe/errors.rb
index c4af5a7a1..b5c2032ca 100644
--- a/lib/stripe/errors.rb
+++ b/lib/stripe/errors.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   # StripeError is the base error from which all other more specific Stripe
   # errors derive.
diff --git a/lib/stripe/event.rb b/lib/stripe/event.rb
index 18fe68fd5..5a627a523 100644
--- a/lib/stripe/event.rb
+++ b/lib/stripe/event.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Event < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/exchange_rate.rb b/lib/stripe/exchange_rate.rb
index ccebbbbfa..2db05dfac 100644
--- a/lib/stripe/exchange_rate.rb
+++ b/lib/stripe/exchange_rate.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class ExchangeRate < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/file_upload.rb b/lib/stripe/file_upload.rb
index 983548a40..f598ab012 100644
--- a/lib/stripe/file_upload.rb
+++ b/lib/stripe/file_upload.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class FileUpload < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/invoice.rb b/lib/stripe/invoice.rb
index bc84d3592..495d66691 100644
--- a/lib/stripe/invoice.rb
+++ b/lib/stripe/invoice.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Invoice < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/invoice_item.rb b/lib/stripe/invoice_item.rb
index 12f6373a8..e5d9b6268 100644
--- a/lib/stripe/invoice_item.rb
+++ b/lib/stripe/invoice_item.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class InvoiceItem < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/invoice_line_item.rb b/lib/stripe/invoice_line_item.rb
index 4703d7fcb..a2056bbc4 100644
--- a/lib/stripe/invoice_line_item.rb
+++ b/lib/stripe/invoice_line_item.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class InvoiceLineItem < StripeObject
     OBJECT_NAME = "line_item".freeze
diff --git a/lib/stripe/issuer_fraud_record.rb b/lib/stripe/issuer_fraud_record.rb
index c686ae590..835b5a8c1 100644
--- a/lib/stripe/issuer_fraud_record.rb
+++ b/lib/stripe/issuer_fraud_record.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class IssuerFraudRecord < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/list_object.rb b/lib/stripe/list_object.rb
index 343d141ee..58cae0adb 100644
--- a/lib/stripe/list_object.rb
+++ b/lib/stripe/list_object.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class ListObject < StripeObject
     include Enumerable
diff --git a/lib/stripe/login_link.rb b/lib/stripe/login_link.rb
index f2b41e4c2..09eba2f4b 100644
--- a/lib/stripe/login_link.rb
+++ b/lib/stripe/login_link.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class LoginLink < APIResource
     OBJECT_NAME = "login_link".freeze
diff --git a/lib/stripe/oauth.rb b/lib/stripe/oauth.rb
index d1b55efa1..a07778ae6 100644
--- a/lib/stripe/oauth.rb
+++ b/lib/stripe/oauth.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module OAuth
     module OAuthOperations
diff --git a/lib/stripe/order.rb b/lib/stripe/order.rb
index c0d682314..3ad042de1 100644
--- a/lib/stripe/order.rb
+++ b/lib/stripe/order.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Order < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/order_return.rb b/lib/stripe/order_return.rb
index ee0683a7a..6940a6f57 100644
--- a/lib/stripe/order_return.rb
+++ b/lib/stripe/order_return.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class OrderReturn < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/payout.rb b/lib/stripe/payout.rb
index 91893a5df..335da40e2 100644
--- a/lib/stripe/payout.rb
+++ b/lib/stripe/payout.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Payout < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/plan.rb b/lib/stripe/plan.rb
index fe01be2be..192bf301b 100644
--- a/lib/stripe/plan.rb
+++ b/lib/stripe/plan.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Plan < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/product.rb b/lib/stripe/product.rb
index f7fe6c5b5..56466908e 100644
--- a/lib/stripe/product.rb
+++ b/lib/stripe/product.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Product < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/recipient.rb b/lib/stripe/recipient.rb
index da20d07a6..bd2d603e8 100644
--- a/lib/stripe/recipient.rb
+++ b/lib/stripe/recipient.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   # Recipients objects are deprecated. Please use Stripe Connect instead.
   class Recipient < APIResource
diff --git a/lib/stripe/recipient_transfer.rb b/lib/stripe/recipient_transfer.rb
index 7128a689d..30faaaee3 100644
--- a/lib/stripe/recipient_transfer.rb
+++ b/lib/stripe/recipient_transfer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class RecipientTransfer < StripeObject
     OBJECT_NAME = "recipient_transfer".freeze
diff --git a/lib/stripe/refund.rb b/lib/stripe/refund.rb
index c08330103..b832b0f07 100644
--- a/lib/stripe/refund.rb
+++ b/lib/stripe/refund.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Refund < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/reversal.rb b/lib/stripe/reversal.rb
index 42d9de732..725de0672 100644
--- a/lib/stripe/reversal.rb
+++ b/lib/stripe/reversal.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Reversal < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/singleton_api_resource.rb b/lib/stripe/singleton_api_resource.rb
index 2748647d5..00abb51ff 100644
--- a/lib/stripe/singleton_api_resource.rb
+++ b/lib/stripe/singleton_api_resource.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class SingletonAPIResource < APIResource
     def self.resource_url
diff --git a/lib/stripe/sku.rb b/lib/stripe/sku.rb
index ada998bb9..c60e70984 100644
--- a/lib/stripe/sku.rb
+++ b/lib/stripe/sku.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class SKU < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/source.rb b/lib/stripe/source.rb
index 399eaba3b..cfa60715a 100644
--- a/lib/stripe/source.rb
+++ b/lib/stripe/source.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Source < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/source_transaction.rb b/lib/stripe/source_transaction.rb
index a661a9a51..545162a03 100644
--- a/lib/stripe/source_transaction.rb
+++ b/lib/stripe/source_transaction.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class SourceTransaction < StripeObject
     OBJECT_NAME = "source_transaction".freeze
diff --git a/lib/stripe/stripe_client.rb b/lib/stripe/stripe_client.rb
index c98a47687..523f4873d 100644
--- a/lib/stripe/stripe_client.rb
+++ b/lib/stripe/stripe_client.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   # StripeClient executes requests against the Stripe API and allows a user to
   # recover both a resource a call returns as well as a response object that
diff --git a/lib/stripe/stripe_object.rb b/lib/stripe/stripe_object.rb
index 3aca0757e..de92a4568 100644
--- a/lib/stripe/stripe_object.rb
+++ b/lib/stripe/stripe_object.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class StripeObject
     include Enumerable
diff --git a/lib/stripe/stripe_response.rb b/lib/stripe/stripe_response.rb
index 3bae162f9..2028d1cc7 100644
--- a/lib/stripe/stripe_response.rb
+++ b/lib/stripe/stripe_response.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   # StripeResponse encapsulates some vitals of a response that came back from
   # the Stripe API.
diff --git a/lib/stripe/subscription.rb b/lib/stripe/subscription.rb
index 90ec34429..285953dac 100644
--- a/lib/stripe/subscription.rb
+++ b/lib/stripe/subscription.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Subscription < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/subscription_item.rb b/lib/stripe/subscription_item.rb
index ab3da8360..91689feb1 100644
--- a/lib/stripe/subscription_item.rb
+++ b/lib/stripe/subscription_item.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class SubscriptionItem < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/three_d_secure.rb b/lib/stripe/three_d_secure.rb
index 191056f4e..e713eb0a9 100644
--- a/lib/stripe/three_d_secure.rb
+++ b/lib/stripe/three_d_secure.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class ThreeDSecure < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/token.rb b/lib/stripe/token.rb
index 71ed05249..acf35275c 100644
--- a/lib/stripe/token.rb
+++ b/lib/stripe/token.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Token < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/topup.rb b/lib/stripe/topup.rb
index 619310fd1..21218e71a 100644
--- a/lib/stripe/topup.rb
+++ b/lib/stripe/topup.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Topup < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/transfer.rb b/lib/stripe/transfer.rb
index a8d5bbaaf..a96e89cae 100644
--- a/lib/stripe/transfer.rb
+++ b/lib/stripe/transfer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Transfer < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/usage_record.rb b/lib/stripe/usage_record.rb
index 255001d54..9f18788ed 100644
--- a/lib/stripe/usage_record.rb
+++ b/lib/stripe/usage_record.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class UsageRecord < APIResource
     def self.create(params = {}, opts = {})
diff --git a/lib/stripe/util.rb b/lib/stripe/util.rb
index c2a4691d2..ebdfa23a2 100644
--- a/lib/stripe/util.rb
+++ b/lib/stripe/util.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "cgi"
 
 module Stripe
diff --git a/lib/stripe/version.rb b/lib/stripe/version.rb
index 91b27e6f4..24f9e11ac 100644
--- a/lib/stripe/version.rb
+++ b/lib/stripe/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   VERSION = "3.14.0".freeze
 end
diff --git a/lib/stripe/webhook.rb b/lib/stripe/webhook.rb
index 0e00890f0..ae8615b4c 100644
--- a/lib/stripe/webhook.rb
+++ b/lib/stripe/webhook.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module Webhook
     DEFAULT_TOLERANCE = 300
diff --git a/stripe.gemspec b/stripe.gemspec
index ad18963d7..e77dcad2e 100644
--- a/stripe.gemspec
+++ b/stripe.gemspec
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 $LOAD_PATH.unshift(File.join(File.dirname(__FILE__), "lib"))
 
 require "stripe/version"
diff --git a/test/api_stub_helpers.rb b/test/api_stub_helpers.rb
index e69de29bb..8e9b8f90f 100644
--- a/test/api_stub_helpers.rb
+++ b/test/api_stub_helpers.rb
@@ -0,0 +1 @@
+# frozen_string_literal: true
diff --git a/test/stripe/account_external_accounts_operations_test.rb b/test/stripe/account_external_accounts_operations_test.rb
index 94ff50e00..703ef6a50 100644
--- a/test/stripe/account_external_accounts_operations_test.rb
+++ b/test/stripe/account_external_accounts_operations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/account_login_links_operations_test.rb b/test/stripe/account_login_links_operations_test.rb
index a2e3f7409..3671ce3dd 100644
--- a/test/stripe/account_login_links_operations_test.rb
+++ b/test/stripe/account_login_links_operations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/account_test.rb b/test/stripe/account_test.rb
index 198bc68f8..2cbc7980d 100644
--- a/test/stripe/account_test.rb
+++ b/test/stripe/account_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/alipay_account_test.rb b/test/stripe/alipay_account_test.rb
index f59253f27..e960f1cf4 100644
--- a/test/stripe/alipay_account_test.rb
+++ b/test/stripe/alipay_account_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/api_operations_test.rb b/test/stripe/api_operations_test.rb
index 4412d1df4..962eaaea3 100644
--- a/test/stripe/api_operations_test.rb
+++ b/test/stripe/api_operations_test.rb
@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/api_resource_test.rb b/test/stripe/api_resource_test.rb
index 336b31c5f..f160fe86d 100644
--- a/test/stripe/api_resource_test.rb
+++ b/test/stripe/api_resource_test.rb
@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/apple_pay_domain_test.rb b/test/stripe/apple_pay_domain_test.rb
index 5c792dca6..3ac50d9fb 100644
--- a/test/stripe/apple_pay_domain_test.rb
+++ b/test/stripe/apple_pay_domain_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/application_fee_refund_test.rb b/test/stripe/application_fee_refund_test.rb
index 07d7c5e7c..c63d7834e 100644
--- a/test/stripe/application_fee_refund_test.rb
+++ b/test/stripe/application_fee_refund_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/application_fee_refunds_operations_test.rb b/test/stripe/application_fee_refunds_operations_test.rb
index 223c3cac7..2f4ad683e 100644
--- a/test/stripe/application_fee_refunds_operations_test.rb
+++ b/test/stripe/application_fee_refunds_operations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/application_fee_test.rb b/test/stripe/application_fee_test.rb
index bed487876..0cabb9b0c 100644
--- a/test/stripe/application_fee_test.rb
+++ b/test/stripe/application_fee_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/balance_test.rb b/test/stripe/balance_test.rb
index 22a707204..772508b54 100644
--- a/test/stripe/balance_test.rb
+++ b/test/stripe/balance_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/bank_account_test.rb b/test/stripe/bank_account_test.rb
index 7ddc201c2..f0ebc0655 100644
--- a/test/stripe/bank_account_test.rb
+++ b/test/stripe/bank_account_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/charge_test.rb b/test/stripe/charge_test.rb
index dadc3530d..44b0da7ce 100644
--- a/test/stripe/charge_test.rb
+++ b/test/stripe/charge_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/country_spec_test.rb b/test/stripe/country_spec_test.rb
index 2dc9e5632..c1e69b787 100644
--- a/test/stripe/country_spec_test.rb
+++ b/test/stripe/country_spec_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/coupon_test.rb b/test/stripe/coupon_test.rb
index bc8e491c2..848be4498 100644
--- a/test/stripe/coupon_test.rb
+++ b/test/stripe/coupon_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/customer_card_test.rb b/test/stripe/customer_card_test.rb
index ab844a146..3e6658fc8 100644
--- a/test/stripe/customer_card_test.rb
+++ b/test/stripe/customer_card_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/customer_sources_operations_test.rb b/test/stripe/customer_sources_operations_test.rb
index c86abcc1f..b89b688e5 100644
--- a/test/stripe/customer_sources_operations_test.rb
+++ b/test/stripe/customer_sources_operations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/customer_test.rb b/test/stripe/customer_test.rb
index ae94b4f3d..d119d1563 100644
--- a/test/stripe/customer_test.rb
+++ b/test/stripe/customer_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/dispute_test.rb b/test/stripe/dispute_test.rb
index 373a4f3f5..8539140e6 100644
--- a/test/stripe/dispute_test.rb
+++ b/test/stripe/dispute_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/ephemeral_key_test.rb b/test/stripe/ephemeral_key_test.rb
index f03409ff3..90dd4f861 100644
--- a/test/stripe/ephemeral_key_test.rb
+++ b/test/stripe/ephemeral_key_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/errors_test.rb b/test/stripe/errors_test.rb
index 4f8a1fe59..9f94e0a87 100644
--- a/test/stripe/errors_test.rb
+++ b/test/stripe/errors_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/exchange_rate_test.rb b/test/stripe/exchange_rate_test.rb
index 65a2ff678..8156eb779 100644
--- a/test/stripe/exchange_rate_test.rb
+++ b/test/stripe/exchange_rate_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/file_upload_test.rb b/test/stripe/file_upload_test.rb
index b2448fcf2..fa79a09d5 100644
--- a/test/stripe/file_upload_test.rb
+++ b/test/stripe/file_upload_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/invoice_item_test.rb b/test/stripe/invoice_item_test.rb
index b40ca8d66..04a0616aa 100644
--- a/test/stripe/invoice_item_test.rb
+++ b/test/stripe/invoice_item_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/invoice_line_item_test.rb b/test/stripe/invoice_line_item_test.rb
index 428fe7cb6..542902782 100644
--- a/test/stripe/invoice_line_item_test.rb
+++ b/test/stripe/invoice_line_item_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/invoice_test.rb b/test/stripe/invoice_test.rb
index dd145c033..ebf8582ad 100644
--- a/test/stripe/invoice_test.rb
+++ b/test/stripe/invoice_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/issuer_fraud_record_test.rb b/test/stripe/issuer_fraud_record_test.rb
index 1b0cc2021..b7462bbc6 100644
--- a/test/stripe/issuer_fraud_record_test.rb
+++ b/test/stripe/issuer_fraud_record_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/list_object_test.rb b/test/stripe/list_object_test.rb
index 296c8ff0f..a9b22ae59 100644
--- a/test/stripe/list_object_test.rb
+++ b/test/stripe/list_object_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/login_link_test.rb b/test/stripe/login_link_test.rb
index 56480a04c..b23397a35 100644
--- a/test/stripe/login_link_test.rb
+++ b/test/stripe/login_link_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/oauth_test.rb b/test/stripe/oauth_test.rb
index 12022d54d..33fcebec6 100644
--- a/test/stripe/oauth_test.rb
+++ b/test/stripe/oauth_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/order_return_test.rb b/test/stripe/order_return_test.rb
index d87f5ad36..2bc2578be 100644
--- a/test/stripe/order_return_test.rb
+++ b/test/stripe/order_return_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/order_test.rb b/test/stripe/order_test.rb
index 8c8258297..ed992f260 100644
--- a/test/stripe/order_test.rb
+++ b/test/stripe/order_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/payout_test.rb b/test/stripe/payout_test.rb
index 0b656c90c..e70f6ade7 100644
--- a/test/stripe/payout_test.rb
+++ b/test/stripe/payout_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/plan_test.rb b/test/stripe/plan_test.rb
index c22adf9d1..531b8ecee 100644
--- a/test/stripe/plan_test.rb
+++ b/test/stripe/plan_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/product_test.rb b/test/stripe/product_test.rb
index 997ce66bd..cff7512f7 100644
--- a/test/stripe/product_test.rb
+++ b/test/stripe/product_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/recipient_test.rb b/test/stripe/recipient_test.rb
index 8265c558f..990a5159d 100644
--- a/test/stripe/recipient_test.rb
+++ b/test/stripe/recipient_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/refund_test.rb b/test/stripe/refund_test.rb
index b82647c88..4708e0b77 100644
--- a/test/stripe/refund_test.rb
+++ b/test/stripe/refund_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/reversal_test.rb b/test/stripe/reversal_test.rb
index 757e6d318..a691866f6 100644
--- a/test/stripe/reversal_test.rb
+++ b/test/stripe/reversal_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/sku_test.rb b/test/stripe/sku_test.rb
index f97f67b42..3b0d3b4b5 100644
--- a/test/stripe/sku_test.rb
+++ b/test/stripe/sku_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/source_test.rb b/test/stripe/source_test.rb
index 33be36909..7a03aa5a7 100644
--- a/test/stripe/source_test.rb
+++ b/test/stripe/source_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/source_transaction_test.rb b/test/stripe/source_transaction_test.rb
index f5ce90c45..f7322cb66 100644
--- a/test/stripe/source_transaction_test.rb
+++ b/test/stripe/source_transaction_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/stripe_client_test.rb b/test/stripe/stripe_client_test.rb
index 137b7eaa2..c9ef34359 100644
--- a/test/stripe/stripe_client_test.rb
+++ b/test/stripe/stripe_client_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/stripe_object_test.rb b/test/stripe/stripe_object_test.rb
index a6c21a02b..aa18aba6f 100644
--- a/test/stripe/stripe_object_test.rb
+++ b/test/stripe/stripe_object_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/stripe_response_test.rb b/test/stripe/stripe_response_test.rb
index a24346977..025d6da62 100644
--- a/test/stripe/stripe_response_test.rb
+++ b/test/stripe/stripe_response_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/subscription_item_test.rb b/test/stripe/subscription_item_test.rb
index 08b37aa61..8033e0c68 100644
--- a/test/stripe/subscription_item_test.rb
+++ b/test/stripe/subscription_item_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/subscription_test.rb b/test/stripe/subscription_test.rb
index ecccf26db..d2c404097 100644
--- a/test/stripe/subscription_test.rb
+++ b/test/stripe/subscription_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/three_d_secure_test.rb b/test/stripe/three_d_secure_test.rb
index c9493cda1..5296e59a2 100644
--- a/test/stripe/three_d_secure_test.rb
+++ b/test/stripe/three_d_secure_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/topup_test.rb b/test/stripe/topup_test.rb
index 14d3c3d36..cd23ba7a8 100644
--- a/test/stripe/topup_test.rb
+++ b/test/stripe/topup_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/transfer_reversals_operations_test.rb b/test/stripe/transfer_reversals_operations_test.rb
index 5fb971178..3101223da 100644
--- a/test/stripe/transfer_reversals_operations_test.rb
+++ b/test/stripe/transfer_reversals_operations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/transfer_test.rb b/test/stripe/transfer_test.rb
index 72de926a8..1f2c26078 100644
--- a/test/stripe/transfer_test.rb
+++ b/test/stripe/transfer_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/usage_record_test.rb b/test/stripe/usage_record_test.rb
index b2742fc22..c3e1f9b66 100644
--- a/test/stripe/usage_record_test.rb
+++ b/test/stripe/usage_record_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/util_test.rb b/test/stripe/util_test.rb
index 90b115ab6..a36ea1ede 100644
--- a/test/stripe/util_test.rb
+++ b/test/stripe/util_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/webhook_test.rb b/test/stripe/webhook_test.rb
index cf4990242..4f4ff4e78 100644
--- a/test/stripe/webhook_test.rb
+++ b/test/stripe/webhook_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe_test.rb b/test/stripe_test.rb
index 0d6f53d80..571a8ac88 100644
--- a/test/stripe_test.rb
+++ b/test/stripe_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../test_helper", __FILE__)
 
 class StripeTest < Test::Unit::TestCase
diff --git a/test/test_data.rb b/test/test_data.rb
index 93c1184e9..d4f030d4f 100644
--- a/test/test_data.rb
+++ b/test/test_data.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module TestData
     def make_error(type, message)
diff --git a/test/test_helper.rb b/test/test_helper.rb
index ba3ec80d0..0a722c379 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "coveralls"
 Coveralls.wear!("test_frameworks")