Testing Time (and Other Asyncronicities)
14 days ago
- #concurrency
- #testing
- #Go programming
- Go 1.24 introduced the experimental `testing/synctest` package to simplify testing concurrent, asynchronous code.
- In Go 1.25, `testing/synctest` graduated to general availability, providing tools for testing asynchronous functions reliably.
- Asynchronous functions differ from synchronous ones by returning before completing their operations, making them harder to test.
- Testing asynchronous code traditionally involves trade-offs between speed and reliability, often resulting in slow or flaky tests.
- The `synctest` package introduces 'bubbles' where tests run with fake time, allowing precise control over timing and synchronization.
- Key features of `synctest` include `Test` for running functions in a bubble and `Wait` for ensuring background activity completes.
- The package helps avoid common pitfalls like deadlocks and race conditions by providing synchronization mechanisms.
- `synctest` improves testing for networked and time-dependent code by using fake time and detecting quiescence.
- Changes from Go 1.24 to 1.25 include renaming `Run` to `Test`, stopping time when the root goroutine returns, and better stack traces.
- Future work may focus on enhancing detection of durably blocked goroutines and improving fake network implementations.