test(conformance): enforce SPARKLINE's fixture coverage again

[hhimanshu]

Third and last PR of the #766 sequence, after #770 (code) and #772 (rows).

Summary

Removes SPARKLINE from pending_fixture_verification, so every_registered_function_has_conformance_coverage enforces it like any other function.

Why this is not bookkeeping

An entry in that set is not a note-to-self — it is a permanent hole in the coverage guard, and the function it names is precisely the one nobody would notice losing coverage. Left in place, SPARKLINE would have been exempt from the guard forever, three PRs after the reason expired.

QUERY is a legitimate long-term entry: its rows genuinely do not exist yet. SPARKLINE's did, and were two PRs away.

Why the exemption was needed at all

Two CI rules deadlock for any new function:

• the coverage guard wants fixture rows before the function is registered
• Check fixture / code separation rejects a PR touching both the canonical TSVs and code

So code-first fails this test, and fixtures-first leaves rows for a function the engine does not have. The only way through is three PRs, with a temporary exemption spanning the middle one.

The comment now describes that sequence as the general procedure, so the next new function follows it deliberately instead of rediscovering the deadlock through a red CI run — which is how this one found it.

How to test

cargo test -p truecalc-core --test conformance every_registered_function_has_conformance_coverage

Passes on this branch. That is the whole point: it proves SPARKLINE's 115 rows genuinely cover it, rather than the exemption having masked a gap. Before #772 landed, this same test failed with SPARKLINE removed — which is what forced the three-PR sequence.

Test plan

• cargo test -p truecalc-core --test conformance every_registered_function_has_conformance_coverage — passes
• Verified on top of merged main (both feat(google)!: SPARKLINE — parse and validate the in-cell chart #770 and fixtures(google): SPARKLINE conformance rows #772 present)
• Single-file, test-only change; no fixture TSVs touched, so the separation check passes
• CI green

Related

• SPARKLINE: implement the Google Sheets in-cell chart function #766 — SPARKLINE (closed by fixtures(google): SPARKLINE conformance rows #772)
• feat(google)!: SPARKLINE — parse and validate the in-cell chart #770 — the implementation · fixtures(google): SPARKLINE conformance rows #772 — the rows
• test(conformance): silently skipped rows assert nothing — 46 in text.tsv alone, and one pair passed for the wrong reason #767 — rows the conformance runner cannot assert
• fix(statistical): MIN returns 0 for an empty array where Sheets returns #REF!, diverging from MAX #771 — MIN's empty-array divergence, recorded in bugs.tsv by fixtures(google): SPARKLINE conformance rows #772

🤖 Generated with Claude Code

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[github-actions]

Test Coverage by Category

Category	Unit Tests	Google Sheets Conformance	Property Cases	Total
Array	42	547/547 ✓	1,000 (2×500)	1,589
Database	35	182/182 ✓	3,500 (7×500)	3,717
Date	369	418/418 ✓	2,500 (5×500)	3,287
Engineering	245	886/888 ⚠	5,500 (11×500)	6,633
Filter	11	80/80 ✓	4,500 (9×500)	4,591
Financial	149	1,208/1,208 ✓	2,000 (4×500)	3,357
Info	0	256/256 ✓	4,500 (9×500)	4,756
Logical	121	263/263 ✓	3,500 (7×500)	3,884
Lookup	69	392/392 ✓	1,000 (2×500)	1,461
Math	536	2,006/2,006 ✓	8,000 (16×500)	10,542
Operator	87	250/250 ✓	7,500 (15×500)	7,837
Parser	83	92/92 ✓	4,000 (8×500)	4,175
Query	37	—	—	37
Statistical	483	3,156/3,156 ✓	5,000 (10×500)	8,639
Text	298	729/733 ⚠	4,000 (8×500)	5,031
Timezone	47	—	—	47
Volatile	0	—	3,500 (7×500)	3,500
Web	29	56/56 ✓	6,000 (12×500)	6,085
Total	2,897	10,521/10,527	66,000 (132×500)	~79,424

_{✓ = 100% passing · ⚠ = known deviation · The ~79,424 total counts formula evaluations (each conformance row and each property case = 1). GitHub Checks reports 3,732 Rust test functions: 2,897 unit + 159 property functions (shown as cases above) + 676 conformance/integration.}