Native GraphQL fixtures (alpha)

graphqlAdapter(schemaSDL, operationText, options) prepares GraphQL variable and response fixtures with the pinned graphql@17.0.2 reference implementation. The adapter accepts text, not a live schema carrying application resolvers. It performs no HTTP, database, subscription-source, or other network operation.

const operation = graphqlAdapter(
  'type User { id: ID! name: String! } type Query { user(id: ID!): User! }',
  'query ($id: ID!) { user(id: $id) { id name } }',
  {
    fieldsIdentity: 'user-fixtures/v1',
    fields: { 'Query.user': ({ args }) => ({ id: args.id, name: 'Ada' }) },
  }
);
const variables = operation.variables.builder().buildValidated();
const response = operation.response(variables).builder().buildValidated();

variables.create() builds encoded input. Its Standard Schema wrapper returns native coerced variables, including operation/input-field defaults, scalar parsing, input-object validation and oneOf semantics. Required/optional input properties are distinct. Runtime SDL does not establish a TypeScript application model: maps remain Record<string, unknown>. Use generated application types explicitly at an independently checked boundary, rather than an unchecked generic cast.

response(encodedVariables) offers create, check, issues, standard, and builder. The native executor implements aliases, fragments, include/skip, argument coercion, enum serialization and null propagation. Explicit field-factory results retain supplied child values and relationships. Missing child values use ordinary generation. Field factories use schema coordinates, receive already coerced arguments and a named generation stream, and never receive a live resolver context. result() returns a native-shaped data/errors result for deliberate error-fixture work; response().create() rejects execution errors.

Response validation checks the selected wire shape, including absence of extra fields and canonical scalar encodings. Abstract types use a supplied __typename, a configured abstractTypes selection, or the first declared possible type. Select __typename in the operation, or configure its concrete type, when validating a non-default abstract variant that is not otherwise identified in the response. Mutations and individual subscription-event responses are fixtures only: neither application mutations nor subscription streams are executed.

Custom scalars require paired, versioned input, output, parseInput, serialize, and parseOutput callbacks. Input generators return encoded variables; output generators return internal resolver values. Response checks decode serialized values through parseOutput before native output coercion, then require the same wire representation. For example, an ISO timestamp can parse to a Date and serialize back to an ISO string without treating the Date as wire JSON.

Profiles are minimal, random and boundary. Lists have an explicit bounded length. Recursive inputs terminate at nullable/list boundaries within resource budgets; non-null structures that cannot fit fail rather than being silently weakened. Schemas and operations have character/token bounds, and execution has field/depth and data-allocation bounds. These checks are not an interruptible sandbox for hostile native callbacks or pathological parser workloads. Callbacks are trusted, pure and synchronous; validation can invoke them more than once. Promise results are rejected and their rejections observed.

Sessions reproduce generation with the same schema, operation, options, factory identities and original encoded variables. Preserve those variables and callback implementations alongside the replay record. Fixed field streams avoid unrelated field-consumption coupling; cross-version output stability is not promised.

Introspection and custom/incremental executable directives are rejected in this fixture path rather than partially emulated. Use explicit execution integrations for their transport semantics. Default issues preserve locations/response paths without echoing variable contents or custom exception messages. Parsing errors retain their cause for deliberate diagnostics.

The compatibility suite installs built tarballs in an isolated consumer, checks public declarations without DOM types, and tests the native runtime rather than a mock. Individual packages are prepared for coordinated publication; no publication is implied by this source.