Strengthen anomaly detector tests for score normalization and threshold-boundary behavior

[Copilot]

This updates pkg/agentdrain/anomaly_test.go to close high-value coverage gaps called out in the issue: score normalization bounds through Analyze, constructor threshold behavior verification through runtime paths, and clearer intent around stateful event analysis tests.

• Score normalization guard via production path

  • Added TestAnalyze_ScoreAlwaysNormalized to assert AnomalyScore stays within [0,1] for both isNew=true and isNew=false when anomaly signals are maximized.

• Threshold boundaries validated through Analyze (not just constructor storage)

  • Extended TestNewAnomalyDetector_ThresholdBoundaries success cases to verify:
    • similarity == threshold is not flagged low,
    • cluster.Size == rareThreshold is flagged rare,
    • values just below similarity threshold behave as expected.

• TestBuildReason parallelization + explicit pointer guard

  • Added top-level t.Parallel().
  • Added require.NotNil before calling buildReason in subtests to make pointer assumptions explicit.

• Stateful test intent clarified

  • Tightened TestAnalyzeEvent commentary to explicitly mark it as intentionally sequential/stateful integration-style behavior.

func TestAnalyze_ScoreAlwaysNormalized(t *testing.T) {
	t.Parallel()
	d, err := NewAnomalyDetector(1.0, 100)
	require.NoError(t, err)

	result := &MatchResult{ClusterID: 1, Similarity: 0.0}
	cluster := &Cluster{ID: 1, Size: 1}
	for _, isNew := range []bool{true, false} {
		report := d.Analyze(result, isNew, cluster)
		require.NotNil(t, report)
		assert.LessOrEqual(t, report.AnomalyScore, 1.0)
		assert.GreaterOrEqual(t, report.AnomalyScore, 0.0)
	}
}

• Fixes [testify-expert] Improve Test Quality: pkg/agentdrain/anomaly_test.go #46635

[Copilot]

Pull request overview

Strengthens anomaly detector tests around threshold boundaries, normalized scores, parallelization, and stateful test intent.

Changes:

• Verifies constructor thresholds through Analyze.
• Adds score-bound checks for maximal anomaly signals.
• Clarifies and improves test execution assumptions.

Show a summary per file

File	Description
pkg/agentdrain/anomaly_test.go	Expands anomaly detector boundary and normalization coverage.

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• Files reviewed: 1/1 changed files
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• Review effort level: Medium

[github-actions]

🎉 This pull request is included in a new release.

Release: v0.82.14