Refactor Retry-After backoff tests

[travis-minke-sap]

Fixes #5967 #5968 #5969

The original implementation used a test http server to validate the timing between successive requests in order to validate the correct backoff calculation. This is rather heavy-weight, and as we've seen is very timing dependent. Overall the test is sound and on consistent/fast hardware runs reliably, but was complicated to understand and brittle on slower/inconsistent hardware.

This most recent flakiness could easily be resolved by adjusting the test's timings to provide a larger buffer to allow for slower runtimes, but there will always be an inherent "limit" at which test slowness will cause a failure. Further this results in the tests themselves taking longer.

Therefore, I am rewriting the test in a (hopefully) simpler fashion. The new test is directly verifying the backoff calculation and skips the eventing sending aspect. This should make them easier to understand and maintain, faster to execute, and no longer subject to slow execution failures (flaky-ness)

The diff is a confusing mess due to overlap with old implementation and I would recommend reviewing the new test on it's own - up to you though ; )

Proposed Changes

• 🧹 Refactor the Retry-After header backoff test.

Pre-review Checklist

• At least 80% unit test coverage
• E2E tests for any new behavior (n/a - existing test change only)
• Docs PR for any user-facing impact (n/a - existing test change only)
• Spec PR for any new API feature (n/a - existing test change only)
• Conformance test for any change to the spec (n/a - existing test change only)

Release Note

Docs

[codecov]

Codecov Report

Merging #5981 (49e0ad3) into main (e00a9f4) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #5981      +/-   ##
==========================================
- Coverage   82.33%   82.31%   -0.03%     
==========================================
  Files         220      220              
  Lines        7564     7564              
==========================================
- Hits         6228     6226       -2     
- Misses        902      903       +1     
- Partials      434      435       +1     

Impacted Files	Coverage Δ
pkg/kncloudevents/message_sender.go	86.27% <0.00%> (-3.93%)	⬇️

---

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[matzew]

/test all

[knative-metrics-robot]

The following is the coverage report on the affected files.
Say /test pull-knative-eventing-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/kncloudevents/message_sender.go	92.5%	90.0%	-2.5

[matzew]

/lgtm
/approve

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: matzew, travis-minke-sap

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[matzew]

SourceToSinkWithDLQ

that is a flake from @gabo1208 's PR

/retest

[matzew]

/retest

On Wed 8. Dec 2021 at 13:09, Knative Prow Robot ***@***.***> wrote: @travis-minke-sap <https://github.com/travis-minke-sap>: The following test *failed*, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests: Test name Commit Details Required Rerun command pull-knative-eventing-reconciler-tests 49e0ad3 <49e0ad3> link <https://prow.knative.dev/view/gs/knative-prow/pr-logs/pull/knative_eventing/5981/pull-knative-eventing-reconciler-tests/1468544366963331072> true /test pull-knative-eventing-reconciler-tests Full PR test history <https://gubernator.knative.dev/pr/knative_eventing/5981>. Your PR dashboard <https://gubernator.knative.dev/pr/travis-minke-sap>. Instructions for interacting with me using PR comments are available here <https://git.k8s.io/community/contributors/guide/pull-requests.md>. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra <https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:> repository. I understand the commands that are listed here <https://go.k8s.io/bot-commands>. — You are receiving this because you were assigned. Reply to this email directly, view it on GitHub <#5981 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABGPTQUTMZBITMAGD35V4TUP5DIHANCNFSM5JSICVVA> .

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