You are deploying a new feature to the test environment and it causes the test environment to go down. What will you do?

First, quickly revert the changes to restore the test environment to a working state and minimize team downtime. Then, analyze logs and errors to understand the cause of the failure. You can use monitoring and debugging tools, such as Node.js logs or tracing. Next, fix the issue in the code, test locally, and only after that, redeploy to the test environment. It is also important to implement automated tests to detect such errors earlier.