Testing should help developers move faster and not break things. When building indexers, that often feels different. That's why we decided to add a built-in tool to Apibara to quickly test your indexers.

If you want to start testing your indexers, update the Apibara CLI to the latest version with:

curl -sL https://install.apibara.com | bash

The new apibara test command implements snapshot testing for Apibara indexers. The first time you run a test, it will fetch actual data from a DNA stream and run your indexer on this data, storing all relevant data (configuration, input stream, and output data) to a snapshot file. You can inspect this file with any text editor and check that the output matches your expectations (pro tip: you can manually edit the result to your liking). Now, you can rerun the test command, and it will replay the stream data from the snapshot file and compare the output of the indexer with what is stored in the snapshot. If the output matches, the test is considered a success. If it fails, the CLI will print an error message showing a difference between the expected and actual results.

The test command provides some options to customize the input stream by specifying a specific block range for replaying data, among other customizations. You can also decide to overwrite an existing snapshot file. We will publish a more detailed testing tutorial in the upcoming days. You can read more by running apibara test --help.