chore: implement phase 2

[Tofel]

Fixes retry-error conflation, measures full poll latency, and hardens the Source test doubles for concurrent use.

Review focus: source.go (error vs retry classification, latency timing) and source_fake_test.go (concurrency safety).

[github-actions]

📊 API Diff Results

No changes detected for module github.com/smartcontractkit/chainlink-testing-framework/grafana-alertcheck

View full report

[Tofel]

Clock skew is only ever needed to place the runner-defined window edges [from, to+grace] onto Grafana's own timeline, so it's a single-point reconciliation, not a factor in any duration-based check. The 60s hard limit is therefore a sanity gate, not a correction: skew is estimated as serverDate − (t_send+t_recv)/2 with error RTT/2, and that estimation is only trusted while the two clocks are in rough agreement. Past 60s the offset is treated as a broken or misconfigured clock, so the gate fails closed rather than align fine-grained window work against a clock it no longer trusts.

[Tofel]

better safe than sorry, we don't want to risk subtle behaviour changes.

[Copilot]

🟡 Changes recommended

It introduces unbounded response-body reads in the HTTP source and the “goroutine-safe” fake returns internal slices without defensive copies, both of which can lead to reliability/concurrency issues.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR introduces the Phase 2 “Source” layer for the Grafana alert gate, including stricter transport vs hard-error classification, full end-to-end poll latency measurement, and concurrency-hardened test doubles.

Changes:

• Add a production httpSource implementing Source, including Grafana version parsing/range enforcement, Date/skew validation, and retry-with-backoff for retryable transport failures.
• Add comprehensive unit tests for skew/date-header hard failures, retry exhaustion semantics, and timing arithmetic (skew bound + full-body latency).
• Expand Prometheus duration parsing negative test coverage with additional invalid inputs.

File summaries

File	Description
grafana-alertcheck/internal/gate/source.go	Adds Source + httpSource, request timing/skew logic, and transport retry/backoff behavior.
grafana-alertcheck/internal/gate/source_test.go	Adds end-to-end tests for version/state/definitions, retry behavior, and timing/skew calculations.
grafana-alertcheck/internal/gate/source_fake_test.go	Adds goroutine-safe fake clock(s) and scripted fake Source for higher-phase tests.
grafana-alertcheck/internal/gate/duration_test.go	Adds more invalid-duration inputs to strengthen parser error coverage.

Review details

Suppressed comments (1)

grafana-alertcheck/internal/gate/source_fake_test.go:132

• RuleState returns next.obs (including obs.Rules) directly. Since the last scripted entry repeats, any caller mutation of the returned slice can leak into future calls and also create cross-goroutine races; copy the Rules slice before returning.

	next := q[0]
	if len(q) > 1 {
		f.states[title] = q[1:]
	}
	return next.obs, next.err
}

• Files reviewed: 4/4 changed files
• Comments generated: 3
• Review effort level: Lite

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.