test(start-client-core): type regression tests for createServerFn GET validator inference (fixes #7671)

[tsushanth]

Summary

Adds three type-level regression tests covering the ctx.data type inference regression reported in #7671, where createServerFn({ method: 'GET' }).validator(schema) caused ctx.data to resolve as unknown instead of the schema's output type.

Cases covered:

1. Bare StandardSchemaV1 object validator — minimal { '~standard': { types, validate } } shape
2. Parse-method validator (zod v3 shape) — { parse(input: unknown): T } (the AnyValidatorObj path)
3. Combined StandardSchema + parse validator (zod 3.25+ shape) — has both ~standard and .parse

All three pass on the current HEAD (1.170.12) with TS 5.9, confirming either: (a) the regression was fixed between 1.168.24 and now, or (b) it's environment/TS-version specific. These tests guard against future regressions.

Closes #7671

Summary by CodeRabbit

• Tests
  • Added coverage for validator type inference with object inputs.
  • Verified server function handlers preserve typed data instead of falling back to unknown.
  • Included regression checks for validators using standard, parse-based, and combined validation patterns.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: d89ed8cc-ef9c-4db4-8128-b8451949072e

📥 Commits

Reviewing files that changed from the base of the PR and between 9809a06 and c1af6ac.

📒 Files selected for processing (1)

• packages/start-client-core/src/tests/createServerFn.test-d.ts

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📝 Walkthrough

Walkthrough

Three new type-level tests were added to createServerFn.test-d.ts to verify TypeScript correctly infers ctx.data as {id: string} for validators using ~standard metadata, parse methods, or both, addressing a prior regression to unknown type inference.

Changes

Validator inference regression tests

Layer / File(s)	Summary
Standard, parse, and combined validator type tests packages/start-client-core/src/tests/createServerFn.test-d.ts	Adds three type-level tests verifying that createServerFn's handler correctly infers ctx.data as {id: string} for ~standard validators, parse-method validators (Zod v3-like), and validators combining both ~standard and parse (Zod v3.25+-like), instead of regressing to unknown.

Estimated code review effort: 1 (Trivial) | ~5 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the new GET validator inference regression tests and references the linked issue.
Linked Issues check	✅ Passed	The added tests cover the GET validator inference regression and the validator shapes described in #7671.
Out of Scope Changes check	✅ Passed	The diff is limited to regression tests for the linked GET validator inference issue.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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