Snapshot testing

[simoneb]

What is the problem this feature will solve?

It would be useful to have snapshot testing as part of the built-in test runner or assertion library.

I am aware of earlier work on this, specifically the inclusion and then removal of assert.snapshot as per #44466 and #46112.

I'm wondering if there's a consensus that snapshot testing should not live in Node core or if you would be open to an implementation without the shortcomings of the earlier one.

What is the feature you are proposing to solve the problem?

I would propose an implementation in Node core, which would play well with the built-in test runner

What alternatives have you considered?

The only real alternative at the moment would be using a different testing framework. I haven't considered whether snapshot testing could be implemented as a standalone library though.

[cjihrig]

I would definitely sign off on a new implementation of assert.snapshot() if it addressed the issues raised with the previous implementation.

[MoLow]

I am +1.
I have added common.assertSnapshot to the internal node test suite - this way we can possibly use that as a foundation

[tniessen]

It would be great to clarify expectations and requirements before we implement any API. assert.snapshot() was deeply flawed in many ways. common.assertSnapshot() is a much simpler internal implementation that may be sufficient for some simple use cases.

For example, would users expect snapshot testing to support data types other than strings?

[MrHBS]

I would just see how other test runners, like Vitest and Jest, implement snapshots and do the same.

[hulkish]

Would really like to see this added to node +1

[JakobJingleheimer]

I think this does not belong in node core because it's too specific. But I think we should facilitate it. In order to do so, I believe we need to expose some additional properties on TestContext:

• file (à la the various events emitted)
• fullName (the concatenated names of self and all ancestors)

Then someone (such as me—I just started a basic package for it to include/reference from the nodejs.org Learn article I'm working on) has sufficient data available to do this.