Function validateImportAttributes

packages/jest-runtime/src/internals/EsmLoader.ts:187–242

(
  modulePath: string,
  attributes: ImportAttributes,
  referencingIdentifier: string,
)

}

export function validateImportAttributes(
  modulePath: string,
  attributes: ImportAttributes,
  referencingIdentifier: string,
): void {
  for (const key of Object.keys(attributes)) {
    if (key !== 'type') {
      throw makeImportAttributeError(
        'ERR_IMPORT_ATTRIBUTE_UNSUPPORTED',
        `Import attribute "${key}" with value "${attributes[key]}" is not supported (importing "${modulePath}" from ${referencingIdentifier})`,
      );
    }
  }

  const declaredType = attributes.type;
  const isJson = isJsonModule(modulePath);

  if (isJson) {
    if (declaredType === undefined) {
      // TODO(jest next major): match Node and throw
      // ERR_IMPORT_ATTRIBUTE_MISSING here. Until then, warn so existing users
      // without `with { type: 'json' }` keep working.
      const dedupeKey = `${referencingIdentifier}::${modulePath}`;
      if (!warnedMissingJsonAttributePairs.has(dedupeKey)) {
        if (warnedMissingJsonAttributePairs.size >= MAX_WARNED_PAIRS) {
          warnedMissingJsonAttributePairs.clear();
        }
        warnedMissingJsonAttributePairs.add(dedupeKey);
        const moduleLabel = describeForWarning(modulePath);
        console.warn(
          'Jest: importing JSON without an import attribute is deprecated and will be a hard error in the next major. ' +
            `Update the import of "${moduleLabel}" (from ${referencingIdentifier}): ` +
            "use `with { type: 'json' }` for static imports, or pass " +
            "`{ with: { type: 'json' } }` as the second argument to dynamic `import()`.",
        );
      }
      return;
    }
    if (declaredType !== 'json') {
      throw makeImportAttributeError(
        'ERR_IMPORT_ATTRIBUTE_TYPE_INCOMPATIBLE',
        `Module "${modulePath}" is not of type "${declaredType}"`,
      );
    }
    return;
  }

  // Non-JSON (implicit-type) module. Per HTML spec, the default type cannot
  // be re-asserted, so any explicit `type` attribute is rejected.
  if (declaredType !== undefined) {
    throw makeImportAttributeError(
      'ERR_IMPORT_ATTRIBUTE_TYPE_INCOMPATIBLE',
      `Module "${modulePath}" is not of type "${declaredType}"`,
    );
  }
}

const ESM_TRANSFORM_OPTIONS: TransformOptions = {