Jest did not exit one second after the test run has completed.

Jest did not exit one second after the test run has completed.

When running tests using Jest, you may encounter a warning or error stating that Jest did not exit one second after the test run has completed. This usually means that some asynchronous operations are still pending, causing the test runner to wait for them to complete before exiting.

This error commonly occurs when:

• There are unresolved promises or callbacks in your test code.
• There are open connections, processes, or resources that have not been properly closed.
• There are ongoing network requests that have not been terminated or timed out.

To troubleshoot and fix this issue, you can follow these steps:

1. Check for any asynchronous operations in your test code that may not be properly resolved or rejected. Make sure you await promises or use async/await syntax correctly.
2. Verify that all resources, connections, or processes utilized in your tests are being correctly closed or cleaned up after usage. For example, closing database connections or stopping servers.
3. Ensure that all network requests in your tests either complete successfully or time out. You can use Jest’s built-in timeout options to control how long the test runner waits before considering a test as failed.

Here’s an example that demonstrates a possible cause of this error:


afterEach(() => {
// Simulating an unresolved promise that causes Jest to keep waiting
return new Promise((resolve) => {
// Resolution of this promise is missing, leading to Jest not exiting
});
});


In this example, the `afterEach` hook returns a promise that never gets resolved, causing Jest to hang indefinitely after the test run is complete.

Make sure to carefully review your test code and ensure that all asynchronous operations are completed or properly cleaned up to avoid this error and ensure Jest exits correctly after the test run.