Today, I'll share a trademark secret that allows us to move fast and make huge changes without fear.

When we're starting a new [Symfony 2.8-7.2 upgrade project](/blog/off-the-beaten-path-to-upgrade-symfony-28-to-72), we cover it with a couple of tests first. These tests are not units, but smoke tests - with a couple of lines they cover a huge portion of the Symfony framework layer we use.

With a couple of lines, we can cover complex container operations and avoid most dummy yet destructive bugs while working with services.

Tomas Votruba

Learn how to implement cost-effective container smoke tests for Symfony upgrades. These tests, which do not depend on Symfony versions, help quickly catch complex bugs in container operations without needing database setups or heavy frameworks. The post goes through the creation of a simple container test case and provides examples for event subscribers and controller instantiations, ensuring reliable testing over various Symfony versions.

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