Return success instead of error when transaction not found in finish()

If a transaction is not found in Transaction.unfinished, it means the transaction has already been finished. This should be treated as a success case rather than an error, since the desired outcome (transaction completed) has been achieved.

This ensures that calling completePurchase() multiple times or on already-finished transactions works correctly, allowing consumable products to be repurchased.

Author: ANONYMOUSZED-beep

packages/in_app_purchase/in_app_purchase_storekit/CHANGELOG.md

@@ -1,7 +1,7 @@
 ## 0.4.6+3
 
 * Fixes `finish()` method to always call its completion handler in StoreKit2.
-* `finish()` now returns an error when the transaction is not found in unfinished transactions.
+* `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

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

@@ -267,16 +267,10 @@ extension InAppPurchasePlugin: InAppPurchase2API {
         let transaction = try await fetchUnfinishedTransaction(by: UInt64(id))
         if let transaction = transaction {
           await transaction.finish()
-          completion(.success(Void()))
-        } else {
-          // Transaction not found in unfinished transactions
-          completion(
-            .failure(
-              PigeonError(
-                code: "storekit2_transaction_not_found",
-                message: "Transaction not found in unfinished transactions.",
-                details: "Transaction ID: \(id)")))
         }
+        // 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(

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

@@ -415,19 +415,18 @@ final class InAppPurchase2PluginTests: XCTestCase {
     await fulfillment(of: [finishExpectation], timeout: 5)
   }
 
-  func testFinishNonExistentTransactionReturnsError() async throws {
-    // Test that finishing a non-existent transaction returns an error
+  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 error")
+      description: "Finishing non-existent transaction should return success")
 
     plugin.finish(id: 999999) { result in
       switch result {
       case .success():
-        XCTFail("Finish should fail for non-existent transaction")
-      case .failure(let error):
-        let pigeonError = error as! PigeonError
-        XCTAssertEqual(pigeonError.code, "storekit2_transaction_not_found")
         finishExpectation.fulfill()
+      case .failure(let error):
+        XCTFail("Finish should succeed for non-existent transaction: \(error)")
       }
     }