[in_app_purchase] Fix an issue causing StoreKit 2 transactions remain unfinished

[edpizzi]

The StoreKit 2 (iOS, MacOS) in_app_purchase backend causes ordinary client use (eg. the in_app_purchase example app) to leave transactions in an unfinished state, contrary to the StoreKit contract.

This happens because StoreKit 2 purchase updates have pendingCompletePurchase == false, causing clients to not call completePurchase (flutter/flutter#180046). This in turn happens because purchase updates incorrectly have state restored instead of purchased (flutter/flutter#172434).

Fix this by keeping track of which TransactionMessages are created in the restorePurchases code path to set the restoring field correctly. Previously it was set whenever a transaction had receipt data (which is also true for ordinary purchase updates). This keeps ordinary purcahses as state purchased. These purchase records will also have pendingCompletePurchase set to true, since this is gated by state purchased.

Fixes:

• [in_app_purchase] StoreKit2 transactions are not finalized when following documentation (eg. in example app) flutter#180046
• in app purchase in iOS always return status == PurchaseStatus.restored when purchasing product flutter#172434

Pre-Review Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter.
• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I linked to at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or I have commented below to indicate which version change exemption this PR falls under¹.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style, or I have commented below to indicate which CHANGELOG exemption this PR falls under¹.
• I updated/added any relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or I have commented below to indicate which test exemption this PR falls under¹.
• All existing and new tests are passing.

Footnotes

1. Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling. ↩ ↩² ↩³

[gemini-code-assist]

Code Review

This pull request correctly fixes an issue where StoreKit 2 transactions were left unfinished. The introduction of a restoring flag to distinguish between new and restored purchases is a solid approach, ensuring that new purchases get the correct purchased status and can be properly completed by the client. The accompanying test updates effectively validate this fix.

I've added one minor suggestion for code clarity. Also, while I understand you skipped running the auto-formatter to ease the review, please ensure it's run before merging to comply with the repository's style guidelines.

[gemini-code-assist]

The string interpolation "\()" around completedPurchase.jwsRepresentation is redundant because jwsRepresentation is already a String. You can simplify the code by passing the property directly for better readability and to adhere to Swift best practices.

              transaction: purchase, receipt: completedPurchase.jwsRepresentation, restoring: true

References

1. The repository style guide requires following language-specific style guides (lines 10-12). In Swift, it's best practice to avoid redundant operations like wrapping an existing string in string interpolation for code clarity. ^(link)

[edpizzi]

I had overlooked the Swift tests under in_app_purchase_storekit/example/shared.RunnerTests. I've now added to them, and changed the callback to save the last update so we can validate that purchase callbacks do not have restoring set.

I've validated that the new assertions fail before this change.