Class 'Tests\Unit\Mockery' not found

Hi,

I can't make Mockery work in my test classes.

The "funny" thing is that it works using thinker

Time: 470 ms, Memory: 10.00MB

There was 1 error:

1) Tests\Unit\SolariumTest::it_search_solarium_and_returns_the_results
Error: Class 'Tests\Unit\Mockery' not found

#my test class
<?php

namespace Tests\Unit;


use Tests\TestCase;


class SolariumTest extends TestCase
{
    public function tearDown()
    {
        Mockery::close();
    }

    /** @test */
    public function it_search_solarium_and_returns_the_results()
    {
        $client = \Mockery::mock(\Solarium\Client::class);
        //$client = Mockery::mock(\Solarium\Client::class);
    }
}

#using tinker

✗ php artisan tinker
Psy Shell v0.8.3 (PHP 7.0.15 — cli) by Justin Hileman
>>> $client = Mockery::mock(\Solarium\Client::class);
=> Mockery_0_Solarium_Client {#937}
>>>

#my composer
{
    "name": "laravel/laravel",
    "description": "The Laravel Framework.",
    "keywords": ["framework", "laravel"],
    "license": "MIT",
    "type": "project",
    "require": {
        "php": ">=5.6.4",
        "barryvdh/laravel-cors": "^0.9.2",
        "barryvdh/laravel-debugbar": "^2.3",
        "laravel/dusk": "^1.0",
        "laravel/framework": "5.4.*",
        "laravel/tinker": "~1.0",
        "laravelcollective/html": "^5.4",
        "solarium/solarium": "^3.8"
    },
    "require-dev": {
        "fzaninotto/faker": "~1.4",
        "mockery/mockery": "~0.9.4",
        "phpunit/phpunit": "~5.7"
    },
    "autoload": {
        "classmap": [
            "database" 
        ],
        "psr-4": {
            "App\\": "app/"
        }
    },
    "autoload-dev": {
        "psr-4": {
            "Tests\\": "tests/"
        }
    },
    "scripts": {
        "post-root-package-install": [
            "php -r \"file_exists('.env') || copy('.env.example', '.env');\""
        ],
        "post-create-project-cmd": [
            "php artisan key:generate"
        ],
        "post-install-cmd": [
            "Illuminate\\Foundation\\ComposerScripts::postInstall",
            "php artisan optimize"
        ],
        "post-update-cmd": [
            "Illuminate\\Foundation\\ComposerScripts::postUpdate",
            "php artisan optimize"
        ]
    },
    "config": {
        "preferred-install": "dist",
        "sort-packages": true,
        "optimize-autoloader": true
    }
}

Any Idea?

Thanks! :)