test(examples): assert generated inferred types contain no unknown recursively

[benjamineckstein]

Summary

The prior schema-shape property test only checked generated SOURCE TEXT for the "unknown" substring. This can be bypassed by a z.infer collapse to unknown: the #383 shape where source text says z.ZodType with no literal "unknown" substring, but the inferred type resolves to unknown. This adds a TYPE-LEVEL recursive DeepHasUnknown<T> assertion over inferred types (model interfaces + z.infer), providing compile-time proof that INFERRED types contain no unknown in any named field recursively.

Changes

• Type-level recursive DeepHasUnknown<T> detector for model interfaces and z.infer results
• Covers bug(openapi-gen): generated model types infer to unknown when input_schema is enabled (z.lazy + bare : z.ZodType) #383 cyclic cases (canada_holidays), bug(openapi-gen): nullable array (type: ["array","null"]) with items emits z.unknown() instead of z.array(...) #390 nullable arrays + object-null (resend), and large breadth example (spotify)
• Correctly ignores intentional .passthrough() catchall index signature
• Self-tests included (with @ts-expect-error) proving detector fires on named/array/union/whole-type unknown and does not over-pass passthrough-like types
• Assertion file: examples/type-assertions.ts wired into examples/tsconfig.json include

Testing

• pnpm --filter @codewithagents/examples run typecheck passes locally
• Detection empirically proven: deliberately-leaky field makes typecheck fail
• pnpm fallow:audit exits 0 (fallow "unused file" warning is warn-level only, expected for type-only assertion)
• No generated files changed
• eslint config does not lint examples/ (expected)

Notes

• This is a test: change. Release Please will NOT create a version bump.
• The fallow "unused file" finding is warn-level and expected for a type-only assertion file. It does not gate the audit.
• Typechecked by Showcase (Drift + Typecheck) and Typecheck Generated Output CI jobs.

Summary by CodeRabbit

• Tests
  • Added TypeScript type validation tests to verify Zod-generated type inferences are accurate across various scenarios, including nullable fields and complex nested schemas. These tests help prevent type-related regressions.

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

Adds examples/type-assertions.ts, a compile-time TypeScript harness that uses recursive conditional types (DeepHasUnknown, AssertNoUnknown) to assert that z.infer<> outputs for cyclic Canada holiday schemas, resend nullable schemas, and Spotify schemas contain no spurious unknown. Updates examples/tsconfig.json to include the new file.

Changes

Compile-time unknown leak assertion harness

Layer / File(s)	Summary
Unknown detection types and tsconfig wiring examples/type-assertions.ts, examples/tsconfig.json	File-level docs describe the passthrough handling approach. IsAny, IsUnknownExact, NamedKeys, DeepHasUnknown, and AssertNoUnknown implement recursive unknown leak detection that ignores wide index signatures. tsconfig.json extends include to cover type-assertions.ts.
Regression assertions for cyclic, resend, and Spotify schemas examples/type-assertions.ts	AssertNoUnknown is applied to HolidaySchema/ProvinceSchema via Pick<> and top-level unknown checks (#383), to RootSchema/ErrorSchema, to resend models (Email, Attachment, Domain, DomainRecord) for nullable array/object-null regressions (#390), and to Spotify types (ArtistObject, TrackObject, AudioFeaturesObject).
Non-vacuous self-tests examples/type-assertions.ts	@ts-expect-error directives require compile failures for unknown leaked in arrays, union members, and whole-type positions, while requiring compile success for a passthrough-like intersection type where the wide index signature is excluded.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• codewithagents/openapi-zod-ts#385: Directly related — fixes the cyclic/self-referential schema generator behavior (#383) that the new HolidaySchema/ProvinceSchema assertions in this PR validate.
• codewithagents/openapi-zod-ts#393: Directly related — fixes the nullable object/unknown-fallback regression (#390) in OpenAPI→Zod type generation that the resend AssertNoUnknown checks in this PR cover.

Poem

🐇 Hoppity-hop through inferred types I go,
Sniffing for unknown that shouldn't be so!
With DeepHasUnknown I dig through each layer,
And @ts-expect-error keeps the detector fair.
No unknown leaks shall slip past my ear—
The types are concrete, the compile is clear! 🎉

🚥 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 accurately reflects the main change: adding a compile-time type assertion mechanism to ensure generated inferred types contain no unknown values recursively. This directly corresponds to the primary addition of type-assertions.ts and the tsconfig.json update.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch test/deep-no-unknown-inferred-types

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 ESLint

If the error stems from missing dependencies, add them to the package.json file. For unrecoverable errors (e.g., due to private dependencies), disable the tool in the CodeRabbit configuration.

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[github-actions]

Fallow audit report

Found 3 findings.

Dead code (1)

Severity	Rule	Location	Description
minor	fallow/unused-file	examples/type-assertions.ts:1	File is not reachable from any entry point

Dependencies (2)

Severity	Rule	Location	Description
minor	fallow/unused-dev-dependency	examples/package.json:15	Package '@tanstack/react-query' is in devDependencies but never imported; imported in other workspaces: packages/integration, packages/petstore-fastify
minor	fallow/unused-dev-dependency	examples/package.json:17	Package 'react' is in devDependencies but never imported; imported in other workspaces: packages/integration, packages/petstore-fastify

Generated by fallow.

[github-actions]

Fallow audit report

1 inline finding selected for GitHub review.

[github-actions]

warn fallow/unused-file: File is not reachable from any entry point

Run fallow fix --files or delete this file.