[in_app_purchase_storekit] Fix consumable repurchase issue in StoreKit2

packages/in_app_purchase/in_app_purchase_storekit/CHANGELOG.md

@@ -1,3 +1,9 @@
+## 0.4.6+3
+
+* Fixes `finish()` method to always call its completion handler in StoreKit2.
+* `finish()` now returns success when the transaction is not found in unfinished transactions (since it's already complete).
+* Adds `fetchUnfinishedTransaction()` helper for looking up transactions that need to be completed.
+
 ## 0.4.6+2
 
 * Updates to Pigeon 26.

packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit/StoreKit2/InAppPurchasePlugin+StoreKit2.swift

@@ -263,10 +263,21 @@ extension InAppPurchasePlugin: InAppPurchase2API {
   /// Wrapper method around StoreKit2's finish() method https://developer.apple.com/documentation/storekit/transaction/3749694-finish
   func finish(id: Int64, completion: @escaping (Result<Void, Error>) -> Void) {
     Task {
-      let transaction = try await fetchTransaction(by: UInt64(id))
-      if let transaction = transaction {
-        await transaction.finish()
+      do {
+        let transaction = try await fetchUnfinishedTransaction(by: UInt64(id))
+        if let transaction = transaction {
+          await transaction.finish()
+        }
+        // If transaction is not found, it means it's already been finished.
+        // This is a success case - the transaction is complete.
         completion(.success(Void()))
+      } catch {
+        completion(
+          .failure(
+            PigeonError(
+              code: "storekit2_finish_transaction_failed",
+              message: "Failed to finish transaction: \(error.localizedDescription)",
+              details: "Transaction ID: \(id)")))
       }
     }
   }
@@ -362,7 +373,24 @@ extension InAppPurchasePlugin: InAppPurchase2API {
     return transactions
   }
 
-  /// Helper function to fetch specific transaction
+  /// Helper function to fetch specific transaction by ID from unfinished transactions.
+  /// Used by finish() to find transactions that need to be completed.
+  func fetchUnfinishedTransaction(by id: UInt64) async throws -> Transaction? {
+    for await result in Transaction.unfinished {
+      switch result {
+      case .verified(let transaction):
+        if transaction.id == id {
+          return transaction
+        }
+      case .unverified:
+        continue
+      }
+    }
+    return nil
+  }
+
+  /// Helper function to fetch specific transaction by ID from all transactions.
+  /// Used for general transaction lookups.
   func fetchTransaction(by id: UInt64) async throws -> Transaction? {
     for await result in Transaction.all {
       switch result {

packages/in_app_purchase/in_app_purchase_storekit/example/shared/RunnerTests/InAppPurchaseStoreKit2PluginTests.swift

@@ -415,6 +415,67 @@ final class InAppPurchase2PluginTests: XCTestCase {
     await fulfillment(of: [finishExpectation], timeout: 5)
   }
 
+  func testFinishNonExistentTransactionReturnsSuccess() async throws {
+    // Test that finishing a non-existent transaction returns success
+    // (since if it's not in unfinished transactions, it's already complete)
+    let finishExpectation = self.expectation(
+      description: "Finishing non-existent transaction should return success")
+
+    plugin.finish(id: 999999) { result in
+      switch result {
+      case .success():
+        finishExpectation.fulfill()
+      case .failure(let error):
+        XCTFail("Finish should succeed for non-existent transaction: \(error)")
+      }
+    }
+
+    await fulfillment(of: [finishExpectation], timeout: 5)
+  }
+
+  func testConsumableCanBeRepurchasedAfterFinish() async throws {
+    // Test that a consumable can be purchased again after finishing
+    let firstPurchaseExpectation = self.expectation(description: "First purchase should succeed")
+    let finishExpectation = self.expectation(description: "Finishing purchase should succeed")
+    let secondPurchaseExpectation = self.expectation(description: "Second purchase should succeed")
+
+    // First purchase
+    plugin.purchase(id: "consumable", options: nil) { result in
+      switch result {
+      case .success:
+        firstPurchaseExpectation.fulfill()
+      case .failure(let error):
+        XCTFail("First purchase should NOT fail. Failed with \(error)")
+      }
+    }
+
+    await fulfillment(of: [firstPurchaseExpectation], timeout: 5)
+
+    // Finish the transaction
+    plugin.finish(id: 0) { result in
+      switch result {
+      case .success():
+        finishExpectation.fulfill()
+      case .failure(let error):
+        XCTFail("Finish should NOT fail. Failed with \(error)")
+      }
+    }
+
+    await fulfillment(of: [finishExpectation], timeout: 5)
+
+    // Second purchase - this should also succeed
+    plugin.purchase(id: "consumable", options: nil) { result in
+      switch result {
+      case .success:
+        secondPurchaseExpectation.fulfill()
+      case .failure(let error):
+        XCTFail("Second purchase should NOT fail. Failed with \(error)")
+      }
+    }
+
+    await fulfillment(of: [secondPurchaseExpectation], timeout: 5)
+  }
+
   @available(iOS 18.0, macOS 15.0, *)
   func testIsWinBackOfferEligibleEligible() async throws {
     let purchaseExpectation = self.expectation(description: "Purchase should succeed")

packages/in_app_purchase/in_app_purchase_storekit/pubspec.yaml

@@ -2,7 +2,7 @@ name: in_app_purchase_storekit
 description: An implementation for the iOS and macOS platforms of the Flutter `in_app_purchase` plugin. This uses the StoreKit Framework.
 repository: https://github.com/flutter/packages/tree/main/packages/in_app_purchase/in_app_purchase_storekit
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+in_app_purchase%22
-version: 0.4.6+2
+version: 0.4.6+3
 
 environment:
   sdk: ^3.9.0