Make object instances in tests readonly

src/StripeTests/Infrastructure/ParameterBuilderTest.cs

@@ -13,7 +13,7 @@ namespace StripeTests
 
     public class ParameterBuilderTest : BaseStripeTest
     {
-        private TestService service;
+        private readonly TestService service;
 
         public ParameterBuilderTest()
         {

src/StripeTests/Infrastructure/StripeResponseTest.cs

@@ -6,7 +6,7 @@ namespace StripeTests
 
     public class StripeResponseTest : BaseStripeTest
     {
-        private StripeList<Charge> charges;
+        private readonly StripeList<Charge> charges;
 
         public StripeResponseTest()
         {

src/StripeTests/Services/Accounts/AccountCreateOptionsTest.cs

@@ -10,7 +10,7 @@ namespace StripeTests
 
     public class AccountCreateOptionsTest : BaseStripeTest
     {
-        private AccountService service;
+        private readonly AccountService service;
 
         public AccountCreateOptionsTest()
         {

src/StripeTests/Services/Accounts/AccountServiceTest.cs

@@ -11,11 +11,11 @@ public class AccountServiceTest : BaseStripeTest
     {
         private const string AccountId = "acct_123";
 
-        private AccountService service;
-        private AccountCreateOptions createOptions;
-        private AccountUpdateOptions updateOptions;
-        private AccountListOptions listOptions;
-        private AccountRejectOptions rejectOptions;
+        private readonly AccountService service;
+        private readonly AccountCreateOptions createOptions;
+        private readonly AccountUpdateOptions updateOptions;
+        private readonly AccountListOptions listOptions;
+        private readonly AccountRejectOptions rejectOptions;
 
         public AccountServiceTest()
         {

src/StripeTests/Services/ApplePayDomains/ApplePayDomainServiceTest.cs

@@ -11,9 +11,9 @@ public class ApplePayDomainServiceTest : BaseStripeTest
     {
         private const string DomainId = "apwc_123";
 
-        private ApplePayDomainService service;
-        private ApplePayDomainCreateOptions createOptions;
-        private ApplePayDomainListOptions listOptions;
+        private readonly ApplePayDomainService service;
+        private readonly ApplePayDomainCreateOptions createOptions;
+        private readonly ApplePayDomainListOptions listOptions;
 
         public ApplePayDomainServiceTest()
         {

src/StripeTests/Services/ApplicationFeeRefunds/ApplicationFeeRefundServiceTest.cs

@@ -12,10 +12,10 @@ public class ApplicationFeeRefundServiceTest : BaseStripeTest
         private const string ApplicationFeeId = "fee_123";
         private const string ApplicationFeeRefundId = "fr_123";
 
-        private ApplicationFeeRefundService service;
-        private ApplicationFeeRefundCreateOptions createOptions;
-        private ApplicationFeeRefundUpdateOptions updateOptions;
-        private ApplicationFeeRefundListOptions listOptions;
+        private readonly ApplicationFeeRefundService service;
+        private readonly ApplicationFeeRefundCreateOptions createOptions;
+        private readonly ApplicationFeeRefundUpdateOptions updateOptions;
+        private readonly ApplicationFeeRefundListOptions listOptions;
 
         public ApplicationFeeRefundServiceTest()
         {

src/StripeTests/Services/ApplicationFees/ApplicationFeeServiceTest.cs

@@ -11,8 +11,8 @@ public class ApplicationFeeServiceTest : BaseStripeTest
     {
         private const string ApplicationFeeId = "fee_123";
 
-        private ApplicationFeeService service;
-        private ApplicationFeeListOptions listOptions;
+        private readonly ApplicationFeeService service;
+        private readonly ApplicationFeeListOptions listOptions;
 
         public ApplicationFeeServiceTest()
         {

src/StripeTests/Services/Balance/BalanceServiceTest.cs

@@ -9,7 +9,7 @@ namespace StripeTests
 
     public class BalanceServiceTest : BaseStripeTest
     {
-        private BalanceService service;
+        private readonly BalanceService service;
 
         public BalanceServiceTest()
         {

src/StripeTests/Services/BalanceTransactions/BalanceTransactionServiceTest.cs

@@ -11,8 +11,8 @@ public class BalanceTransactionServiceTest : BaseStripeTest
     {
         private const string BalanceTransactionId = "txn_123";
 
-        private BalanceTransactionService service;
-        private BalanceTransactionListOptions listOptions;
+        private readonly BalanceTransactionService service;
+        private readonly BalanceTransactionListOptions listOptions;
 
         public BalanceTransactionServiceTest()
         {

src/StripeTests/Services/BankAccounts/BankAccountListOptionsTest.cs

@@ -10,7 +10,7 @@ namespace StripeTests
 
     public class BankAccountListOptionsTest : BaseStripeTest
     {
-        private BankAccountService service;
+        private readonly BankAccountService service;
 
         public BankAccountListOptionsTest()
         {

src/StripeTests/Services/BankAccounts/BankAccountServiceTest.cs

@@ -12,11 +12,11 @@ public class BankAccountServiceTest : BaseStripeTest
         private const string CustomerId = "cus_123";
         private const string BankAccountId = "ba_123";
 
-        private BankAccountService service;
-        private BankAccountCreateOptions createOptions;
-        private BankAccountUpdateOptions updateOptions;
-        private BankAccountListOptions listOptions;
-        private BankAccountVerifyOptions verifyOptions;
+        private readonly BankAccountService service;
+        private readonly BankAccountCreateOptions createOptions;
+        private readonly BankAccountUpdateOptions updateOptions;
+        private readonly BankAccountListOptions listOptions;
+        private readonly BankAccountVerifyOptions verifyOptions;
 
         public BankAccountServiceTest()
         {

src/StripeTests/Services/Cards/CardListOptionsTest.cs

@@ -10,7 +10,7 @@ namespace StripeTests
 
     public class CardListOptionsTest : BaseStripeTest
     {
-        private CardService service;
+        private readonly CardService service;
 
         public CardListOptionsTest()
         {

src/StripeTests/Services/Cards/CardServiceTest.cs

@@ -16,10 +16,10 @@ public class CardServiceTest : BaseStripeTest
         private const string CardId = "card_123";
         private const string CustomerId = "cus_123";
 
-        private CardService service;
-        private CardCreateOptions createOptions;
-        private CardUpdateOptions updateOptions;
-        private CardListOptions listOptions;
+        private readonly CardService service;
+        private readonly CardCreateOptions createOptions;
+        private readonly CardUpdateOptions updateOptions;
+        private readonly CardListOptions listOptions;
 
         public CardServiceTest()
         {

src/StripeTests/Services/Charges/ChargeServiceTest.cs

@@ -11,11 +11,11 @@ public class ChargeServiceTest : BaseStripeTest
     {
         private const string ChargeId = "ch_123";
 
-        private ChargeService service;
-        private ChargeCaptureOptions captureOptions;
-        private ChargeCreateOptions createOptions;
-        private ChargeUpdateOptions updateOptions;
-        private ChargeListOptions listOptions;
+        private readonly ChargeService service;
+        private readonly ChargeCaptureOptions captureOptions;
+        private readonly ChargeCreateOptions createOptions;
+        private readonly ChargeUpdateOptions updateOptions;
+        private readonly ChargeListOptions listOptions;
 
         public ChargeServiceTest()
         {

src/StripeTests/Services/CountrySpecs/CountrySpecServiceTest.cs

@@ -11,8 +11,8 @@ public class CountrySpecServiceTest : BaseStripeTest
     {
         private const string CountrySpecId = "US";
 
-        private CountrySpecService service;
-        private CountrySpecListOptions listOptions;
+        private readonly CountrySpecService service;
+        private readonly CountrySpecListOptions listOptions;
 
         public CountrySpecServiceTest()
         {

src/StripeTests/Services/Coupons/CouponCreateOptionsTest.cs

@@ -10,7 +10,7 @@ namespace StripeTests
 
     public class CouponCreateOptionsTest : BaseStripeTest
     {
-        private CouponService service;
+        private readonly CouponService service;
 
         public CouponCreateOptionsTest()
         {

src/StripeTests/Services/Coupons/CouponServiceTest.cs

@@ -11,10 +11,10 @@ public class CouponServiceTest : BaseStripeTest
     {
         private const string CouponId = "co_123";
 
-        private CouponService service;
-        private CouponCreateOptions createOptions;
-        private CouponUpdateOptions updateOptions;
-        private CouponListOptions listOptions;
+        private readonly CouponService service;
+        private readonly CouponCreateOptions createOptions;
+        private readonly CouponUpdateOptions updateOptions;
+        private readonly CouponListOptions listOptions;
 
         public CouponServiceTest()
         {

src/StripeTests/Services/Customers/CustomerServiceTest.cs

@@ -11,10 +11,10 @@ public class CustomerServiceTest : BaseStripeTest
     {
         private const string CustomerId = "cus_123";
 
-        private CustomerService service;
-        private CustomerCreateOptions createOptions;
-        private CustomerUpdateOptions updateOptions;
-        private CustomerListOptions listOptions;
+        private readonly CustomerService service;
+        private readonly CustomerCreateOptions createOptions;
+        private readonly CustomerUpdateOptions updateOptions;
+        private readonly CustomerListOptions listOptions;
 
         public CustomerServiceTest()
         {

src/StripeTests/Services/Discounts/DiscountServiceTest.cs

@@ -9,7 +9,7 @@ namespace StripeTests
 
     public class DiscountServiceTest : BaseStripeTest
     {
-        private DiscountService service;
+        private readonly DiscountService service;
 
         public DiscountServiceTest()
         {

src/StripeTests/Services/Disputes/DisputeServiceTest.cs

@@ -11,9 +11,9 @@ public class DisputeServiceTest : BaseStripeTest
     {
         private const string DisputeId = "dp_123";
 
-        private DisputeService service;
-        private DisputeUpdateOptions updateOptions;
-        private DisputeListOptions listOptions;
+        private readonly DisputeService service;
+        private readonly DisputeUpdateOptions updateOptions;
+        private readonly DisputeListOptions listOptions;
 
         public DisputeServiceTest()
         {

src/StripeTests/Services/EphemeralKeys/EphemeralKeyServiceTest.cs

@@ -11,8 +11,8 @@ public class EphemeralKeyServiceTest : BaseStripeTest
     {
         private const string EphemeralKeyId = "ephkey_123";
 
-        private EphemeralKeyService service;
-        private EphemeralKeyCreateOptions createOptions;
+        private readonly EphemeralKeyService service;
+        private readonly EphemeralKeyCreateOptions createOptions;
 
         public EphemeralKeyServiceTest()
         {

src/StripeTests/Services/Events/EventServiceTest.cs

@@ -11,8 +11,8 @@ public class EventServiceTest : BaseStripeTest
     {
         private const string EventId = "evt_123";
 
-        private EventService service;
-        private EventListOptions listOptions;
+        private readonly EventService service;
+        private readonly EventListOptions listOptions;
 
         public EventServiceTest()
         {

src/StripeTests/Services/Events/EventUtilityTest.cs

@@ -5,10 +5,10 @@ namespace StripeTests
 
     public class EventUtilityTest : BaseStripeTest
     {
-        private long eventTimestamp;
-        private string signature;
-        private string json;
-        private string secret;
+        private readonly long eventTimestamp;
+        private readonly string signature;
+        private readonly string json;
+        private readonly string secret;
 
         public EventUtilityTest()
         {

src/StripeTests/Services/ExchangeRates/ExchangeRateServiceTest.cs

@@ -9,8 +9,8 @@ namespace StripeTests
 
     public class ExchangeRateServiceTest : BaseStripeTest
     {
-        private ExchangeRateService service;
-        private ExchangeRateListOptions listOptions;
+        private readonly ExchangeRateService service;
+        private readonly ExchangeRateListOptions listOptions;
 
         public ExchangeRateServiceTest()
         {

src/StripeTests/Services/ExternalAccounts/ExternalAccountServiceTest.cs

@@ -12,10 +12,10 @@ public class ExternalAccountServiceTest : BaseStripeTest
         private const string AccountId = "acct_123";
         private const string ExternalAccountId = "ba_123";
 
-        private ExternalAccountService service;
-        private ExternalAccountCreateOptions createOptions;
-        private ExternalAccountUpdateOptions updateOptions;
-        private ExternalAccountListOptions listOptions;
+        private readonly ExternalAccountService service;
+        private readonly ExternalAccountCreateOptions createOptions;
+        private readonly ExternalAccountUpdateOptions updateOptions;
+        private readonly ExternalAccountListOptions listOptions;
 
         public ExternalAccountServiceTest()
         {

src/StripeTests/Services/FileLinks/FileLinkServiceTest.cs

@@ -11,10 +11,10 @@ public class FileLinkServiceTest : BaseStripeTest
     {
         private const string FileLinkId = "link_123";
 
-        private FileLinkService service;
-        private FileLinkCreateOptions createOptions;
-        private FileLinkUpdateOptions updateOptions;
-        private FileLinkListOptions listOptions;
+        private readonly FileLinkService service;
+        private readonly FileLinkCreateOptions createOptions;
+        private readonly FileLinkUpdateOptions updateOptions;
+        private readonly FileLinkListOptions listOptions;
 
         public FileLinkServiceTest()
         {

src/StripeTests/Services/Files/FileServiceTest.cs

@@ -15,9 +15,9 @@ public class FileServiceTest : BaseStripeTest
         private const string FileId = "file_123";
         private const string FileName = "StripeTests.Resources.file_upload_logo.png";
 
-        private FileService service;
-        private FileCreateOptions createOptions;
-        private FileListOptions listOptions;
+        private readonly FileService service;
+        private readonly FileCreateOptions createOptions;
+        private readonly FileListOptions listOptions;
 
         public FileServiceTest()
         {

src/StripeTests/Services/InvoiceItems/InvoiceItemServiceTest.cs

@@ -11,10 +11,10 @@ public class InvoiceItemServiceTest : BaseStripeTest
     {
         private const string InvoiceItemId = "ii_123";
 
-        private InvoiceItemService service;
-        private InvoiceItemCreateOptions createOptions;
-        private InvoiceItemUpdateOptions updateOptions;
-        private InvoiceItemListOptions listOptions;
+        private readonly InvoiceItemService service;
+        private readonly InvoiceItemCreateOptions createOptions;
+        private readonly InvoiceItemUpdateOptions updateOptions;
+        private readonly InvoiceItemListOptions listOptions;
 
         public InvoiceItemServiceTest()
         {

src/StripeTests/Services/Invoices/InvoiceServiceTest.cs

@@ -11,18 +11,18 @@ public class InvoiceServiceTest : BaseStripeTest
     {
         private const string InvoiceId = "in_123";
 
-        private InvoiceService service;
-        private InvoiceCreateOptions createOptions;
-        private InvoiceUpdateOptions updateOptions;
-        private InvoicePayOptions payOptions;
-        private InvoiceListOptions listOptions;
-        private InvoiceListLineItemsOptions listLineItemsOptions;
-        private UpcomingInvoiceOptions upcomingOptions;
-        private UpcomingInvoiceListLineItemsOptions upcomingListLineItemsOptions;
-        private InvoiceFinalizeOptions finalizeOptions;
-        private InvoiceMarkUncollectibleOptions markUncollectibleOptions;
-        private InvoiceSendOptions sendOptions;
-        private InvoiceVoidOptions voidOptions;
+        private readonly InvoiceService service;
+        private readonly InvoiceCreateOptions createOptions;
+        private readonly InvoiceUpdateOptions updateOptions;
+        private readonly InvoicePayOptions payOptions;
+        private readonly InvoiceListOptions listOptions;
+        private readonly InvoiceListLineItemsOptions listLineItemsOptions;
+        private readonly UpcomingInvoiceOptions upcomingOptions;
+        private readonly UpcomingInvoiceListLineItemsOptions upcomingListLineItemsOptions;
+        private readonly InvoiceFinalizeOptions finalizeOptions;
+        private readonly InvoiceMarkUncollectibleOptions markUncollectibleOptions;
+        private readonly InvoiceSendOptions sendOptions;
+        private readonly InvoiceVoidOptions voidOptions;
 
         public InvoiceServiceTest()
         {

src/StripeTests/Services/Issuing/Authorizations/AuthorizationServiceTest.cs

@@ -11,9 +11,9 @@ public class AuthorizationServiceTest : BaseStripeTest
     {
         private const string AuthorizationId = "iauth_123";
 
-        private AuthorizationService service;
-        private AuthorizationUpdateOptions updateOptions;
-        private AuthorizationListOptions listOptions;
+        private readonly AuthorizationService service;
+        private readonly AuthorizationUpdateOptions updateOptions;
+        private readonly AuthorizationListOptions listOptions;
 
         public AuthorizationServiceTest()
         {