Add validation to catch blank ephemeral keys in CustomerConfiguration

We currently don't validate that an ephemeral key is non-empty when a
user includes it in the `CustomerConfiguration`. This ends up giving
users a pretty obscure error in the API response, and is difficult to
debug today.

Including this validation will catch this issue early and provide users
a better debugging experience.

StripePaymentSheet/Project.swift

@@ -12,5 +12,5 @@ let project = Project.stripeFramework(
  .project(target: "StripePayments", path: "//StripePayments"),
  .project(target: "StripePaymentsUI", path: "//StripePaymentsUI"),
  ],
- unitTestOptions: .testOptions()
+ unitTestOptions: .testOptions(usesPreconditionTesting: true)
 )

StripePaymentSheet/StripePaymentSheet.xcodeproj/project.pbxproj

@@ -136,6 +136,7 @@
  791D8D5E9AD66572132CF18A /* [email protected] in Resources */ = {isa = PBXBuildFile; fileRef = 6C599C4F3933B4A6F0D99004 /* [email protected] */; };
  7B52F499141CCA2514A361F3 /* LinkKeyboardAvoidingScrollView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 37130B660E4A5D6297F83EE8 /* LinkKeyboardAvoidingScrollView.swift */; };
  7B6F620759307A9E1D223E8C /* Date+Distance.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3898FF5D7EBA6D48F7B16647 /* Date+Distance.swift */; };
+ 7B730323DC024AB253FD972C /* CwlPreconditionTesting in Frameworks */ = {isa = PBXBuildFile; productRef = 055CD8CC02F886381222CFD8 /* CwlPreconditionTesting */; };
  7B76E1348EF5FE3C19619E49 /* LinkPaymentMethodPicker-CellContentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5DC05704665DAAA925897779 /* LinkPaymentMethodPicker-CellContentView.swift */; };
  7D840FBB66787B0A8BE16901 /* [email protected] in Resources */ = {isa = PBXBuildFile; fileRef = 1A40E15840B1B116B2A6C188 /* [email protected] */; };
  7E73F6BB38F72678C7302C5F /* [email protected] in Resources */ = {isa = PBXBuildFile; fileRef = 0F4F1936B8B820E7355BC438 /* [email protected] */; };
@@ -246,6 +247,7 @@
  F86342791A503A98C40004F4 /* [email protected] in Resources */ = {isa = PBXBuildFile; fileRef = F63F6E62695BEAC410F641F0 /* [email protected] */; };
  F8CAEC73CE96F289226AE760 /* [email protected] in Resources */ = {isa = PBXBuildFile; fileRef = 5D7B682C467DD8466DFAD143 /* [email protected] */; };
  F90B7028426261188B66C834 /* Error+PaymentSheet.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0EA56C3880C50858583CE468 /* Error+PaymentSheet.swift */; };
+ F99455BCF386126F4D2BD64E /* PaymentSheetConfigurationTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = E578E39D2BDD6444B6C306B4 /* PaymentSheetConfigurationTests.swift */; };
  FA565C353EAD9D94B39CFE16 /* AddressViewController+Configuration.swift in Sources */ = {isa = PBXBuildFile; fileRef = 88F07B4F8F79F5A01F830180 /* AddressViewController+Configuration.swift */; };
  FAB721318163CB8DF4EA2286 /* Stripe3DS2.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 9300105117D75EDBB229C14F /* Stripe3DS2.framework */; };
  FAEB5ABECF32197709B2B19E /* PaymentSheet+SwiftUI.swift in Sources */ = {isa = PBXBuildFile; fileRef = B9A9FDAE66ADA08D85D74E19 /* PaymentSheet+SwiftUI.swift */; };
@@ -548,6 +550,7 @@
  E32B3AC4CC1C4F2DEEC5F292 /* WalletHeaderView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WalletHeaderView.swift; sourceTree = "<group>"; };
  E41AA4E90E5BB28D588FDE51 /* StripeCore.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = StripeCore.framework; sourceTree = BUILT_PRODUCTS_DIR; };
  E5240ECFD40B8605939C4E09 /* LinkMoreInfoView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LinkMoreInfoView.swift; sourceTree = "<group>"; };
+ E578E39D2BDD6444B6C306B4 /* PaymentSheetConfigurationTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PaymentSheetConfigurationTests.swift; sourceTree = "<group>"; };
  E5AC1850BF283EEA0DF89679 /* SavedPaymentMethodsViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SavedPaymentMethodsViewController.swift; sourceTree = "<group>"; };
  E6DDBBAAC2892467CED23402 /* PaymentSheetError.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PaymentSheetError.swift; sourceTree = "<group>"; };
  E77A5A5E70770575F1D02837 /* LinkEnabledPaymentMethodElement.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LinkEnabledPaymentMethodElement.swift; sourceTree = "<group>"; };
@@ -588,6 +591,7 @@
  files = (
  935E8F18F1468A215A06ED29 /* XCTest.framework in Frameworks */,
  8CFF112D4CA7DC217CC36FF7 /* StripePaymentSheet.framework in Frameworks */,
+ 7B730323DC024AB253FD972C /* CwlPreconditionTesting in Frameworks */,
  );
  runOnlyForDeploymentPostprocessing = 0;
  };
@@ -996,6 +1000,7 @@
  children = (
  CBB05D43F6A475F28E0BD38D /* DictionaryTests.swift */,
  BB48D1FD7CD00B3DF85C5FC1 /* Info.plist */,
+ E578E39D2BDD6444B6C306B4 /* PaymentSheetConfigurationTests.swift */,
  7D8FE374BAAD0EDA9FEEF550 /* STPAnalyticsClient+PaymentSheetTests.swift */,
  );
  path = StripePaymentSheetTests;
@@ -1359,6 +1364,9 @@
  73532AF26E428E7914BA99B8 /* PBXTargetDependency */,
  );
  name = StripePaymentSheetTests;
+ packageProductDependencies = (
+ 055CD8CC02F886381222CFD8 /* CwlPreconditionTesting */,
+ );
  productName = StripePaymentSheetTests;
  productReference = 4C6AA41454A6757B3E26AE67 /* StripePaymentSheetTests.xctest */;
  productType = "com.apple.product-type.bundle.unit-test";
@@ -1441,6 +1449,9 @@
  "zh-Hant",
  );
  mainGroup = AEBF7882CCDBB20F4DF60861;
+ packageReferences = (
+ 8B63060E38D65571F89E0AB2 /* XCRemoteSwiftPackageReference "CwlPreconditionTesting" */,
+ );
  productRefGroup = 5A3D81E5A62FDBB1DDA44C53 /* Products */;
  projectDirPath = "";
  projectRoot = "";
@@ -1533,6 +1544,7 @@
  buildActionMask = 2147483647;
  files = (
  D90987C72BBD76D20D60CE04 /* DictionaryTests.swift in Sources */,
+ F99455BCF386126F4D2BD64E /* PaymentSheetConfigurationTests.swift in Sources */,
  52B734BA0B91706F37025523 /* STPAnalyticsClient+PaymentSheetTests.swift in Sources */,
  );
  runOnlyForDeploymentPostprocessing = 0;
@@ -1886,6 +1898,24 @@
  defaultConfigurationName = Release;
  };
 /* End XCConfigurationList section */
+
+/* Begin XCRemoteSwiftPackageReference section */
+ 8B63060E38D65571F89E0AB2 /* XCRemoteSwiftPackageReference "CwlPreconditionTesting" */ = {
+ isa = XCRemoteSwiftPackageReference;
+ repositoryURL = "https://github.com/mattgallagher/CwlPreconditionTesting";
+ requirement = {
+ kind = upToNextMajorVersion;
+ minimumVersion = 2.1.2;
+ };
+ };
+/* End XCRemoteSwiftPackageReference section */
+
+/* Begin XCSwiftPackageProductDependency section */
+ 055CD8CC02F886381222CFD8 /* CwlPreconditionTesting */ = {
+ isa = XCSwiftPackageProductDependency;
+ productName = CwlPreconditionTesting;
+ };
+/* End XCSwiftPackageProductDependency section */
  };
  rootObject = 803994135025BA7DC77E3F4A /* Project object */;
 }

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/PaymentSheetConfiguration.swift

@@ -172,11 +172,13 @@ extension PaymentSheet {
  /// See https://stripe.com/docs/api/customers/object#customer_object-id
  public let id: String
 
- /// A short-lived token that allows the SDK to access a Customer's payment methods
+ /// A short-lived token that allows the SDK to access a Customer's payment methods. Cannot be empty
  public let ephemeralKeySecret: String
 
  /// Initializes a CustomerConfiguration
  public init(id: String, ephemeralKeySecret: String) {
+ assert(!ephemeralKeySecret.isEmpty, "Ephemeral key secret cannot be empty")
+
  self.id = id
  self.ephemeralKeySecret = ephemeralKeySecret
  }

StripePaymentSheet/StripePaymentSheetTests/PaymentSheetConfigurationTests.swift

@@ -0,0 +1,21 @@
+//
+// PaymentSheetConfigurationTests.swift
+// StripePaymentSheetTests
+//
+// Copyright © 2023 Stripe, Inc. All rights reserved.
+//
+
+import CwlPreconditionTesting
+import StripePaymentSheet
+import XCTest
+
+final class PaymentSheetConfigurationTests: XCTestCase {
+
+ func test_customerConfigurationInit_assertsWhenEphemeralKeyIsBlank() throws {
+ let exception = catchBadInstruction {
+ _ = PaymentSheet.CustomerConfiguration(id: "foo", ephemeralKeySecret: "")
+ }
+
+ XCTAssertNotNil(exception)
+ }
+}