| /** @category Validation Rules */ |
| import type { ASTVisitor } from '../../language/visitor'; |
| import type { ValidationContext } from '../ValidationContext'; |
| /** |
| * Possible fragment spread |
| * |
| * A fragment spread is only valid if the type condition could ever possibly |
| * be true: if there is a non-empty intersection of the possible parent types, |
| * and possible types which pass the type condition. |
| * @param context - The validation context used while checking the document. |
| * @returns A visitor that reports validation errors for this rule. |
| * @example |
| * ```ts |
| * import { buildSchema, parse, validate } from 'graphql'; |
| * import { PossibleFragmentSpreadsRule } from 'graphql/validation'; |
| * |
| * const schema = buildSchema(` |
| * type Query { |
| * dog: Dog |
| * } |
| * |
| * type Dog { |
| * barkVolume: Int |
| * } |
| * |
| * type Cat { |
| * meowVolume: Int |
| * } |
| * `); |
| * |
| * const invalidDocument = parse(` |
| * { dog { ... on Cat { meowVolume } } } |
| * `); |
| * const invalidErrors = validate(schema, invalidDocument, [PossibleFragmentSpreadsRule]); |
| * |
| * invalidErrors.length; // => 1 |
| * |
| * const validDocument = parse(` |
| * { dog { ... on Dog { barkVolume } } } |
| * `); |
| * const validErrors = validate(schema, validDocument, [PossibleFragmentSpreadsRule]); |
| * |
| * validErrors; // => [] |
| * ``` |
| */ |
| export declare function PossibleFragmentSpreadsRule( |
| context: ValidationContext, |
| ): ASTVisitor; |