Add discriminatedUnion kind to V2RuntimeSchema coercion

[jar-stripe]

Why?

The sdk-codegen now emits a discriminatedUnion schema kind for V2 methods whose request/response types contain discriminated unions with int64_string or decimal_string fields that need runtime coercion. The stripe-node runtime needs to handle this new schema kind.

What?

• Adds {kind: 'discriminatedUnion', discriminator: string, variants: Record<string, V2RuntimeSchema>} to the V2RuntimeSchema type in Types.ts
• Adds case 'discriminatedUnion': to both coerceV2RequestData and coerceV2ResponseData in V2Coercion.ts
• Runtime behavior: inspects data[schema.discriminator], looks up the matching variant schema, and recursively coerces only that variant's fields. If the discriminator value isn't found or data doesn't have the field, returns data as-is.
• Adds 16 tests covering matching variants, unknown/missing discriminator, null passthrough, and non-object graceful handling

Changelog

• Adds runtime support for coercing int64/decimal fields within discriminated union variants in V2 API responses and requests

[Copilot]

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

Suppressed comments (2)

src/V2Coercion.ts:153

• discriminatorValue in schema.variants also returns true for properties inherited from Object.prototype (e.g. toString), which can cause schema.variants[discriminatorValue] to be a non-schema value and break coercion. Use an own-property check instead.

      const obj = data as Record<string, unknown>;
      const discriminatorValue = obj[schema.discriminator];
      if (
        typeof discriminatorValue === 'string' &&
        discriminatorValue in schema.variants
      ) {
        return coerceV2ResponseData(data, schema.variants[discriminatorValue]);
      }

src/V2Coercion.ts:70

• discriminatorValue in schema.variants also returns true for properties inherited from Object.prototype (e.g. toString), which can cause schema.variants[discriminatorValue] to be a non-schema value and break coercion. Use an own-property check instead.

This issue also appears on line 146 of the same file.

      const discriminatorValue = obj[schema.discriminator];
      if (
        typeof discriminatorValue === 'string' &&
        discriminatorValue in schema.variants
      ) {
        return coerceV2RequestData(data, schema.variants[discriminatorValue]);
      }

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

Suppressed comments (3)

src/V2Coercion.ts:152

• Using the in operator here can match properties inherited from Object.prototype (e.g. toString, __proto__), which could cause an unintended variant match and then pass a non-schema value into coercion (leading to schema.kind being undefined and returning undefined). Prefer an own-property check on variants.

      if (
        typeof discriminatorValue === 'string' &&
        discriminatorValue in schema.variants
      ) {
        return coerceV2ResponseData(data, schema.variants[discriminatorValue]);

src/V2Coercion.ts:70

• Using the in operator here can match properties inherited from Object.prototype (e.g. toString, __proto__), which could cause an unintended variant match and then pass a non-schema value into coercion (leading to schema.kind being undefined and returning undefined). Prefer an own-property check on variants.

This issue also appears on line 148 of the same file.

      if (
        typeof discriminatorValue === 'string' &&
        discriminatorValue in schema.variants
      ) {
        return coerceV2RequestData(data, schema.variants[discriminatorValue]);

test/DiscriminatedUnion.spec.ts:8

• This comment claims these hand-written types "exactly match" what codegen emits, but the file doesn't reference generated types or schemas, so it can drift and become misleading. Consider softening the wording to avoid asserting exact equivalence.

// Type definitions mirroring the shapes the codegen produces for discriminated
// unions.  These are hand-written here so the test file is self-contained, but
// they exactly match the object-literal typedef shape the Node generator emits
// for each variant.

[xavdid]

This could also be a good opportunity for type narrowing tests! (which we have already)