[misc] Remove unit test cases that fail the admission criteria (round 2) (#30703)

.claude/rules/unit-test-admission.md

@@ -35,6 +35,35 @@ Not admissible:
 - Mirror tests that restate the implementation logic as assertions.
 - Probabilistic stress that cannot reproduce the failure it claims to guard.
 
+**Distinguishing test — does deletion leave a silent-failure path?** A case
+that *looks* like a tautology/mirror is still admissible when it guards a
+failure mode no other case covers. The criterion is not "is the code under
+test simple?" but "would some regression pass every remaining test if this
+case were deleted?"
+
+Keep (bookkeeping, not mirror) when the assertion guards one of:
+
+- An **external-source literal** — a value copied from an outside spec
+  (OTel semantic conventions, a protocol field name, a vendor API shape).
+  Deleting it removes the only guard against silently copying the spec wrong.
+  Example: `assertEqual(SpanAttributes.GEN_AI_LATENCY_E2E, "gen_ai.latency.e2e")`
+  stays — the string is dictated by the OTel spec, not by this repo's code.
+- A **completeness / negative-branch contract** — "all builtins are
+  registered", "a non-matching id does *not* trigger", "the default is
+  applied when the input is absent". Even if the code is a one-liner, the
+  failure mode is "someone added X without updating Y" or "a predicate
+  degraded to always-true". Example: `test_abort_non_matching_rid` (asserts
+  an unmatched rid is *not* aborted) stays because no positive-match test
+  covers the no-op branch.
+
+Delete (true mirror/tautology) when the assertion merely echoes an
+**isolated** implementation output — changing it breaks nothing outside the
+line itself, so the test has no independent guard value. Example:
+`assertEqual(MixedPrecisionConfig.get_min_capability(),
+Fp4Config.get_min_capability())` goes — the source body is literally
+`return Fp4Config.get_min_capability()`, and flipping it is an isolated
+change that every dependent test catches anyway.
+
 One strong case beats several weak ones: each additional case must guard a
 distinct failure mode. Ask "which bug escapes if I delete this case?" -- no
 answer means delete it.