Add license and README

LICENSE

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Package.swift

@@ -5,6 +5,9 @@ import PackageDescription
 
 let package = Package(
     name: "StoreKitTestHelpers",
+    platforms: [
+        .iOS(.v16),
+    ],
     products: [
         // Products define the executables and libraries a package produces, making them visible to other packages.
         .library(

README.md

@@ -0,0 +1,36 @@
+# StoreKitTestHelpers
+
+StoreKitTestHelpers is a little utility to help reduce test flakiness when using StoreKitTest. 
+
+The root of the problem seems to be that Apple's StoreKitTest mock server sometimes does not get shut down properly between test runs, and can alternate between the correct response and stale incorrect response. This package provides some helpers to spin until StoreKit returns consistent results (by default, 3 times in a row).
+
+## Installation
+
+### Swift Package Manager
+
+Add the following to your `Package.swift` file:
+
+```swift
+.package(url: "https://github.com/dropbox/StoreKitTestHelpers.git", .upToNextMajor(from: "1.0.0")),
+```
+
+## Usage
+
+```swift
+import StoreKitTest
+import StoreKitTestHelpers
+
+func testBlockingExample() {
+    // set up your test session
+    let skTestSession = try SKTestSession.clearedNonInteractiveSession() 
+    // buys product and waits until StoreKit has expected auto-renewable subscription
+    try await skTestSession.buyProductAndWait(identifier: "com.example.product")
+    // alternatively - make purchase other ways and wait
+    try await skTestSession.spinUntilActiveAutoRenewableProductIdsContains("com.example.product")
+
+    // you can also wait until arbitrary conditions are met X times in a row
+    try await Task.spinUntilCondition {
+        await example.shouldBlockPurchase()
+    }
+}
+```

Sources/StoreKitTestHelpers/SKTestSession+TestHelpers.swift

@@ -0,0 +1,136 @@
+import StoreKitTest
+import XCTest
+
+@available(iOS 17.0, *)
+extension SKTestSession {
+    /// This will buy the product(s) and then wait until internal StoreKit state is updated before returning. This is necessary to prevent StoreKitTest/StoreKit2 test flakes
+    @MainActor
+    public func buyProductAndWait(
+        identifier: String,
+        options: Set<Product.PurchaseOption> = [],
+        file: StaticString = #filePath,
+        line: UInt = #line
+    ) async throws {
+        try await buyProduct(identifier: identifier, options: options)
+        try await spinUntilActiveAutoRenewableProductIdsContains(identifier: identifier, file: file, line: line)
+    }
+}
+
+@available(iOS 16.0, *)
+extension SKTestSession {
+    /// For some reason the internal StoreKit state is not updated immediately, even after awaiting the previous step.
+    /// We have to wait some indeterminate amount of time to avoid flakes, but I'm guessing this is still probably a little flakey
+    @MainActor
+    @discardableResult public func spinUntilActiveAutoRenewableProductIdsContains(
+        identifier: String,
+        maxTries: Int = 1_000,
+        file: StaticString = #filePath,
+        line: UInt = #line
+    ) async throws -> Int {
+        let prefix = "\(((file.description) as NSString).lastPathComponent) L\(line)"
+        let attempts = try await Task.spinUntilCondition(condition: {
+            let activeAutoRenewableProductIDs = await Transaction.activeAutoRenewableProductIDs()
+            return activeAutoRenewableProductIDs.contains(identifier)
+        }, maxTries: maxTries, file: file, line: line)
+        let activeAutoRenewableProductIDs = await Transaction.activeAutoRenewableProductIDs()
+        // SKTestSession.allTransactions will probably contain the transaction immediately
+        // but querying StoreKit2 directly will not reflect that state for usually ~25 attempts
+        let allTransactions = allTransactions()
+        let purchasedTransactionProductIDs = Set(allTransactions.filter {
+            $0.state == .purchased
+        }.map(\.productIdentifier))
+        if Set(activeAutoRenewableProductIDs) != purchasedTransactionProductIDs {
+            print(
+                "\(prefix): WARNING: activeAutoRenewableProductIDs[\(activeAutoRenewableProductIDs.joined(separator: ","))] != purchasedTransactionProductIDs[\(purchasedTransactionProductIDs.joined(separator: ","))]"
+            )
+        }
+        return attempts
+    }
+}
+
+@available(iOS 16.0, *)
+extension Task where Failure == Never, Success == Never {
+    enum SpinError: Error { case exceededTimeout }
+
+    /// Sometimes we have to wait some indeterminate amount of time to avoid flakes, this is a utility to help you tear out your hair less
+    @MainActor
+    @discardableResult public static func spinUntilCondition(
+        condition: () async throws -> Bool,
+        maxTries: Int = 1_000,
+        minimumConsecutiveConsistency: Int = 3,
+        skipTestForTimeouts: Bool = true,
+        sleepDuration: TimeInterval = 0.025,
+        file: StaticString = #filePath,
+        line: UInt = #line
+    ) async throws -> Int {
+        let start = Date()
+
+        var lastConditionResults: [Bool] = []
+        for i in 0 ... maxTries {
+            let prefix = "\(((file.description) as NSString).lastPathComponent) L\(line)"
+
+            if !lastConditionResults.isEmpty, lastConditionResults.count > minimumConsecutiveConsistency {
+                _ = lastConditionResults.removeFirst()
+            }
+            let conditionResult = try await condition()
+            lastConditionResults.append(conditionResult)
+            if lastConditionResults.count >= minimumConsecutiveConsistency,
+               lastConditionResults.allSatisfy({ $0 }) {
+                let end = Date()
+                let duration = end.timeIntervalSince(start)
+                let formattedDuration = "(\(duration.formatted(.number.precision(.fractionLength(1)))) seconds)"
+                if i > minimumConsecutiveConsistency {
+                    print(
+                        "\(prefix): Took \(i + 1) tries \(formattedDuration) until conditions are what we expect"
+                    )
+                } else {
+                    print(
+                        "\(prefix): condition hit on the first \(minimumConsecutiveConsistency) tries \(formattedDuration), nice!"
+                    )
+                }
+                return i
+            }
+            if i > maxTries / 2 {
+                try await Task.sleep(for: .nanoseconds(UInt64(TimeInterval(NSEC_PER_SEC) * sleepDuration)))
+            } else {
+                await Task.yield()
+            }
+        }
+        let end = Date()
+        let duration = end.timeIntervalSince(start)
+        let failureMessage =
+            "Internal state failed to update after \(maxTries) tries (\(duration.formatted(.number.precision(.fractionLength(1)))) seconds), this is a known flake"
+        if skipTestForTimeouts {
+            throw XCTSkip(
+                failureMessage,
+                file: file,
+                line: line
+            )
+        } else {
+            throw SpinError.exceededTimeout
+        }
+    }
+}
+
+extension Transaction {
+    static func activeAutoRenewableProductIDs() async -> [String] {
+        await currentAutoRenewableTransactions().map(\.productID)
+    }
+
+    /// This includes `Transaction.currentEntitlements` which is limited to subscribed or inGracePeriod, however it does not check validity
+    static func currentAutoRenewableTransactions() async -> [Transaction] {
+        var transactions = [Transaction]()
+        // Iterate through all of the user's purchased products.
+        for await result in Transaction.currentEntitlements {
+            do {
+                let transaction = try result.payloadValue
+                if transaction.productType == .autoRenewable {
+                    transactions.append(transaction)
+                }
+            } catch {
+                print("currentAutoRenewableTransactions transaction error, skipping: \(result.unsafePayloadValue.productID) \(error)")
+            }
+        }
+        return transactions
+    }
+}

Tests/StoreKitTestHelpersTests/StoreKitTestHelpersTests.swift

@@ -1,4 +1,6 @@
 import XCTest
+import StoreKitTest
+
 @testable import StoreKitTestHelpers
 
 final class StoreKitTestHelpersTests: XCTestCase {