fix(core): leave allOf-wrapped ref discriminator properties untouched

[ErfanBagheri404]

Fixes #3991

Summary

When a oneOf discriminator mapping targets a member whose discriminator property is an allOf wrapping a single $ref to a shared enum component (the shape drf-spectacular emits when a member accepts multiple discriminator values), resolveDiscriminators merged the mapping keys into the allOf wrapper itself. The zod generator then rendered the chimera as EventTypeEnum.enum(['Pause', 'Session']) — .enum on a ZodEnum is its values object, not callable, so the generated code failed with TS2349.

resolveDiscriminators now skips the merge entirely for allOf-wrapped single-$ref properties: the referenced shared schema already carries the full set of valid values, so the property stays exactly as declared.

Output after the fix (from the issue's repro)

export const SessionEventRef = zod.object({
  "id": zod.string(),
  "type": EventTypeEnum
});

Verified end-to-end by running orval on the issue's spec with client: 'zod' and generateReusableSchemas: true.

Notes

A bare $ref discriminator property already took a different (safe) path via the isReference short-circuit; this fix gives the allOf-wrapped variant the same leave-it-alone treatment.

Summary by CodeRabbit

• Bug Fixes

  • Preserved discriminator properties wrapped in a single reference without adding unintended enum or type values.
  • Improved schema resolution for shared discriminator definitions.

• Tests

  • Added regression coverage to verify discriminator properties remain unchanged in this scenario.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

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Run ID: 51702289-0efe-40e6-930f-64e4f2495583

📥 Commits

Reviewing files that changed from the base of the PR and between 43dd303 and a62e8af.

📒 Files selected for processing (2)

• packages/core/src/getters/discriminators.test.ts
• packages/core/src/getters/discriminators.ts

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📝 Walkthrough

Walkthrough

resolveDiscriminators now preserves discriminator properties that wrap one $ref in allOf. A regression test verifies that the property keeps its existing title and structure without injected enum or type values.

Changes

Discriminator preservation

Layer / File(s)	Summary
Preserve single-reference discriminator properties packages/core/src/getters/discriminators.ts, packages/core/src/getters/discriminators.test.ts	The resolver skips mapping-value merging for a discriminator property whose allOf contains one $ref. The test verifies that the referenced shared enum remains unchanged.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to a62e8

Discriminator properties that wrap a shared enum reference in a single allOf now remain direct references, preventing invalid generated Zod enum calls while preserving shared schema reuse.

Suggested reviewers: snebjorn

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: preserving discriminator properties that are allOf wrappers around a single $ref.
Linked Issues check	✅ Passed	The implementation and regression test address issue #3991. The change prevents enum merging into allOf-wrapped shared references and preserves direct shared-schema reuse.
Out of Scope Changes check	✅ Passed	The changes are limited to the discriminator resolution fix and its regression test. They directly support the linked issue objectives, with no unrelated code changes identified.

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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