RUM-16331: Add integration test for cross-product trace sampling rebasing#3464
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## develop #3464 +/- ##
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- Coverage 72.31% 72.17% -0.14%
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Files 964 964
Lines 35500 35500
Branches 5897 5897
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- Hits 25670 25621 -49
- Misses 8237 8274 +37
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What does this PR do?
Adds
TraceCrossProductSamplingTestinreliability/single-fit/okhttp/with 13 integration tests that verify the rebased effective sample rate (traceSampleRate × sessionSampleRate / 100) is correctly applied end-to-end through both SDK entry points that wireSessionRebasedSampler.Motivation
Follow-up to RUM-15138 (PR #3402). Originated from this review comment.
Additional Notes
Test structure (13 tests):
DatadogInterceptor— 6 curated boundary tests (rebased keep/drop, rebasing changes outcome vs raw rate, sessionRate=100/0 edges, traceRate=0 edge).ApmNetworkInstrumentationConfigurationwithheaderPropagationOnly— 3 curated boundary tests.(traceRate, sessionRate)pair — 2 statistical tests (one per entry point).Determinism approach: Curated session UUIDs are pre-computed from the Knuth-hash math in
DeterministicSampler, yielding exact sampled/dropped outcomes without statistical tolerance. Aggregate tests use Forge-seeded random tokens with ±5pp tolerance.Observation channel: Both rebased paths drop the client-side span (
DatadogInterceptor.canSendSpan = falsewhen RUM is registered;headerPropagationOnlydrops by design), so assertions target the propagatedx-datadog-sampling-priorityrequest header viaMockWebServer.No production code changes. Test-only PR.
Review checklist (to be filled by reviewers)