`anyOf`/`oneOf` false negative: the 20-error cap aborts branch iteration

[shadowhand]

PHP version

8.5

duyler/openapi version

0.7.0

OpenAPI spec version

3.0

Description

AbstractCompositionalValidator::validateSchemas() stops collecting errors after MAX_COMPOSITION_ERRORS (20) — but it does so with a return, which abandons the remaining branches instead of just the remaining errors. If earlier branches produce 20+ errors, a later branch that would match is never evaluated, $validCount stays 0, and anyOf reports "At least one of the schemas must match, but none did".

The result is a validation outcome that depends on the declaration order of the branches, which is not something anyOf semantics allow.

Steps to reproduce

<?php

declare(strict_types=1);

use Duyler\OpenApi\Builder\OpenApiValidatorBuilder;
use Duyler\OpenApi\Validator\Exception\ValidationException;

require __DIR__ . '/vendor/autoload.php';

/** Shaped like a JSON:API resource: an identifier schema composed with a closed attribute schema. */
function resource(string $type, array $attributes): array
{
    return [
        'allOf' => [
            [
                'type' => 'object',
                'required' => ['type'],
                'properties' => ['type' => ['type' => 'string', 'enum' => [$type]]],
            ],
            [
                'type' => 'object',
                'properties' => [
                    'attributes' => [
                        'type' => 'object',
                        'additionalProperties' => false,
                        'properties' => array_fill_keys($attributes, ['type' => 'string']),
                    ],
                ],
            ],
        ],
    ];
}

$noisy = resource('patients', ['first_name', 'last_name']);
$matching = resource('flows', ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k']);

// Matches the `flows` schema, and nothing else.
$flow = [
    'type' => 'flows',
    'attributes' => array_fill_keys(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k'], 'x'),
];

$spec = [
    'openapi' => '3.0.0',
    'info' => ['title' => 'anyOf branch cap', 'version' => '1.0.0'],
    'paths' => [],
    'components' => [
        'schemas' => [
            'Noisy' => $noisy,
            'Matching' => $matching,
            // Identical branch sets, different order.
            'MatchingLast' => ['anyOf' => [
                ['$ref' => '#/components/schemas/Noisy'],
                ['$ref' => '#/components/schemas/Noisy'],
                ['$ref' => '#/components/schemas/Matching'],
            ]],
            'MatchingFirst' => ['anyOf' => [
                ['$ref' => '#/components/schemas/Matching'],
                ['$ref' => '#/components/schemas/Noisy'],
                ['$ref' => '#/components/schemas/Noisy'],
            ]],
        ],
    ],
];

$validator = OpenApiValidatorBuilder::create()->fromJsonString(json_encode($spec))->build();

foreach (['MatchingFirst', 'MatchingLast'] as $schema) {
    try {
        $validator->validateSchema($flow, "#/components/schemas/$schema");
        printf("%-14s => PASS\n", $schema);
    } catch (ValidationException $e) {
        printf("%-14s => FAIL  %s (%d errors)\n", $schema, $e->getMessage(), count($e->getErrors()));
    }
}

Actual result

MatchingFirst  => PASS
MatchingLast   => FAIL  At least one of the schemas must match, but none did (21 errors)

Root Cause

src/Validator/SchemaValidator/AbstractCompositionalValidator.php:37-63:

foreach ($schemas as $subSchema) {
    $outcome = $this->validateBranch($data, $subSchema, $context, $schemaType);

    if ($outcome->matched) {
        ++$validCount;
        continue;
    }

    foreach ($outcome->errors as $error) {
        $errors[] = $error;
    }

    foreach ($outcome->abstractErrors as $error) {
        $abstractErrors[] = $error;

        if (self::MAX_COMPOSITION_ERRORS <= count($abstractErrors)) {
            $abstractErrors[] = new TooManyErrorsError(
                max: self::MAX_COMPOSITION_ERRORS,
                dataPath: $dataPath,
            );

            return new ValidationResult($validCount, $errors, $abstractErrors);   // ← leaves the outer foreach
        }
    }
}

The return exits validateSchemas() entirely. An error cap silently becomes a branch cap.

AnyOfValidator then sees 0 === $result->validCount and throws; OneOfValidator is affected the same way, and can also under-count matches (turning a legitimate single match into "none did"). AllOfValidator is unaffected in outcome — it already fails — but it under-reports which branches failed.

[milinsky]

@shadowhand Thanks for your issue. I will soon release a large number of fixes and improvements from the dev branch and return to your pull requests.