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Known issues

The Workers Vitest pool is currently in open beta. The following are issues Cloudflare is aware of and fixing:

​​ Coverage

Native code coverage via V8 is not supported. You must use instrumented code coverage via Istanbul instead. Refer to the Vitest Coverage documentation for setup instructions.

​​ Fake timers

Vitest’s fake timers do not apply to KV, R2 and cache simulators. For example, you cannot expire a KV key by advancing fake time.

​​ Automatically re-running tests with SELF

If you are writing integration tests with SELF, you must import your Worker’s main entry point in your test file for tests to re-run when files change. For example, if main was set to ./src/index.ts, include import "./src/index" at the top of each test file. Vite’s module analysis that powers hot-module-reloading is performed statically and currently does not detect the dynamic import of main in our test runner.

​​ console.log()s with SELF

console.log()s inside export default { ... } handlers are not shown when writing integration tests with SELF if the handler does no asynchronous work. You can work around this by including ctx.waitUntil(scheduler.wait(100)) in your tests during debugging to keep the request context alive for long enough.

​​ Dynamic import() statements with SELF and Durable Objects

Dynamic import() statements do not work inside export default { ... } handlers when writing integration tests with SELF, or inside Durable Object event handlers. You must import and call your handlers directly, or use static import statements in the global scope.

​​ Durable Object alarms

Durable Object alarms are not reset between test runs and do not respect isolated storage. Ensure you delete or run all alarms with runDurableObjectAlarm() scheduled in each test before finishing the test.