Final Class Yiisoft\Validator\Rule\TrueValueHandler

                public function validate(mixed $value, RuleInterface $rule, ValidationContext $context): Result
{
    if (!$rule instanceof TrueValue) {
        throw new UnexpectedRuleException(TrueValue::class, $rule);
    }
    if (!is_scalar($value)) {
        $parameters = $this->getCommonResultParameters($rule, $context);
        $parameters['type'] = get_debug_type($value);
        return (new Result())->addError($rule->getIncorrectInputMessage(), $parameters);
    }
    if ($rule->isStrict()) {
        $valid = $value === $rule->getTrueValue();
    } else {
        $valid = $value == $rule->getTrueValue();
    }
    if ($valid) {
        return new Result();
    }
    $parameters = $this->getCommonResultParameters($rule, $context);
    $parameters['value'] = $value;
    return (new Result())->addError($rule->getMessage(), $parameters);
}