Use new expect() syntax in script templates

[andrewslotin]

What?

Update script templates used by k6 new to use the new expect() syntax introduced in k6-jslib-testing

Why?

k6-jslib-testing aims to replace the old check() API with a flexible and user-friendly set o matchers. This PR updates the templates used by k6 new to use this API.

Checklist

• I have performed a self-review of my code.
• I have commented on my code, particularly in hard-to-understand areas.
• I have added tests for my changes.
• I have run linter and tests locally (make check) and all pass.
• I have added the correct milestone and labels to the PR.

[ankur22]

LGTM 🚀

I personally prefer the new asserts library, but i think check still has a place, especially in load testing and when working with thresholds. Does it make sense to have a check example in the template with a comment as to why we might want that or is that not needed for this particular template?

[andrewslotin]

@ankur22, the plan is to move away from check() in long-term. In future k6-testing will become the go-to API to assert on values and needs to have feature parity with check(). I'm wondering what are the use-cases that currently cannot be covered by expect()?

[oleiade]

🚀

[oleiade]

@andrewslotin We have, at this point, explicitly excluded emitting assertion-related metrics, by design, because it wasn't part of the initial intent. That's the main difference. We could eventually address that difference, but I'm not entirely sure how much work would be needed.