Resolving Jest Database Test Timeout Issues with Testcontainers in Node.js and TypeScript

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Troubleshooting Jest Database Test Timeout Issues with Testcontainers

The Problem

You may often find that even though your tests appear to run successfully, they do not terminate as expected, leaving you stuck in a moment of uncertainty. This scenario usually arises from issues related to database connections and timers.

In this specific case:

You are using Testcontainers to manage PostgreSQL during testing.

Your createUser method is being tested, which interacts with the database to create a user, fetch its details, and manage associated tags.

While manual testing works, running tests through Jest does not terminate properly.

Understanding the Code

Here's a brief breakdown of the code at play:

createUser Function

This function begins a database transaction, attempts to create a user, and if successful, it commits the transaction. If there is an error, it rolls back the transaction.

It also handles the creation of any tags associated with the user.

Test Setup

The Jest test initializes a PostgreSQL container and prepares the database schema.

It runs a test to verify that a user can be created and returned with the correct values.

The Solution

Steps to Resolve the Issue

Remove Fake Timers:

Since using fake timers can impact asynchronous code properly closing out and terminating, you should consider removing this line unless absolutely necessary.

Test Implementation:

Ensure that your test properly cleans up by making sure you release any connections and resources.

Confirm that all operations in your database are awaited; not awaiting an operation could lead to unexpected behavior.

Use Real Timers:

If your tests do rely on timestamps or any timing-related functionalities, revert to using real timers to ensure that Jest waits appropriately for all promises to resolve before closing out the tests.

Here’s the modified part of the test file:

[[See Video to Reveal this Text or Code Snippet]]

Additional Debugging

If the problem persists after making the above changes, try these additional debug steps:

Inspect connection logs closely to ensure there are no lingering connections.

Add logging statements in your finally blocks to verify that the client connections are releasing properly.

Check if there are unhandled promise rejections that might be causing your tests to hang.

Conclusion

By identifying and addressing the use of fake timers in Jest, along with ensuring proper connection management, you can ensure that your database tests using Testcontainers run effectively and terminate as expected.

The next time you grapple with Jest tests not terminating, consider these solutions, and happy testing!