<?php

namespace Schuppo\PasswordStrength;

class PasswordStrength
{
    public function validateLetters($value)
    {
        return preg_match('/\pL/', $value);
    }

    public function validateNumbers($value)
    {
        return preg_match('/\pN/', $value);
    }

    public function validateCaseDiff($value)
    {
        return preg_match('/(\p{Ll}+.*\p{Lu})|(\p{Lu}+.*\p{Ll})/u', $value);
    }

    public function validateSymbols($value)
    {
        return preg_match('/[!@#$%^&*?()\-_=+{};:,<.>]/', $value);
    }
}

<?php

namespace Schuppo\PasswordStrength;

class PasswordStrength
{
    public function validateLetters($value)
    {
        return preg_match('/\pL/', $value);
    }

    public function validateNumbers($value)
    {
        return preg_match('/\pN/', $value);
    }

    public function validateCaseDiff($value)
    {
        return preg_match('/(\p{Ll}+.*\p{Lu})|(\p{Lu}+.*\p{Ll})/u', $value);
    }

    public function validateSymbols($value)
    {
        return preg_match('/[!@#$%^&*?()\-_=+{};:,<.>\/]/', $value);
    }
}

Add slash to symbol characters
Add slash to symbol characters

Passwords which only contain a slash as symbol currently do fail the validateSymbols category. Therefore the missing slash has been added to the symbols regex