refactor: improve handling of intervals in tedge-flows

[jarhodes314]

Proposed changes

Refactor tedge-flows to improve interval handling.

Previously, tedge-flows relied on an exact number of seconds passing to execute an interval, and this had two negative effects:

• If tedge-flows was experiencing resource-pressure/needed to execute a moderately long-running javascript process, it could miss a tick entirely just by being a second late
• If we wanted to test the intervals for real, the intervals used need to be multiple seconds long to definitively assert the interval is behaving, which is non-ideal for unit/integration tests

This PR fixes both of these issues, allowing arbitrary precision intervals that are guaranteed to execute once the interval has elapsed, regardless of how long it takes tedge-flows to inspect the pending tasks. Additionally, the new approach supports the tokio::time mocking API, so I have added some deterministic integration tests that don't require sleeping whatsoever.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (general improvements like code refactoring that doesn't explicitly fix a bug or add any new functionality)
• Documentation Update (if none of the other choices apply)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Paste Link to the issue

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s. You can activate automatic signing by running just prepare-dev once)
• I ran just format as mentioned in CODING_GUIDELINES
• I used just check as mentioned in CODING_GUIDELINES
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[codecov]

Codecov Report

❌ Patch coverage is 63.79310% with 21 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/extensions/tedge_flows/src/runtime.rs	52.94%	8 Missing ⚠️
crates/core/tedge/src/cli/flows/test.rs	0.00%	6 Missing ⚠️
crates/extensions/tedge_flows/src/js_script.rs	77.77%	3 Missing and 1 partial ⚠️
crates/extensions/tedge_flows/src/flow.rs	80.00%	1 Missing and 1 partial ⚠️
crates/extensions/tedge_flows/src/actor.rs	83.33%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
709	0	3	709	100	2h5m3.128178s

[didier-wenzek]

I would pass now as an argument of the method. Having the time externalized makes things easier to test. Using tokio::time mocking helps for unit tests, but is useless for tedge flows test

[didier-wenzek]

I see pros and cons to externalize or not the check if this call is timely. What are your motivation to move this check out?

[jarhodes314]

For the functions the javascript module exports for tedge-flows to call, my expectation is that the methods on JsScript serve as a lightweight wrapper, doing minimal work beyond calling the function with the provided input. It also feels like a bit of a hack to pretend the function produced no output when it wasn't called at all (or if it entirely doesn't exist).

[didier-wenzek]

It's okay for this PR to have a should_execute_interval function inside the js_script module. However, this abstraction will also be useful for rust-based flow steps as well as for sources producing data at a regular pace.

[didier-wenzek]

Approved. I appreciate the really nice unit test suite.