After you add or update tags to support purchase-detail reports, you can use Google Tag Assistant to validate the tags.
Tag Assistant will:
Check the syntax of the purchase-details variable. For example, if you accidently define two IDs for a single product, or specify the wrong data type for a field, Tag Assistant will display an error.
Provide a preview of the data that's collected by the tag.
Perform checks on other variables within each tag