Shadow's test run feature allows you to preview shadow events for confirmed transactions, before actually deploying changes to your shadow fork.
This makes it easier to:
Iterate on your shadow contract changes
Verify that you're getting the data you expect
Inspect particularly complex transactions
Open editor mode for a contract and make changes
Compile your shadow contract
Click "test run" and paste in a transaction hash
Preview your shadow event data
If you're happy with the data results, deploy the contract
