An autoload.php for PHPUnit with Laravel 5+.

autoload.php

<?php
// Put me into tests/autoload.php
require_once __DIR__.'/../vendor/autoload.php';

try {
    $env = env('APP_ENV');
    $filename = sprintf(".env.%s", $env);
    (new Dotenv\Dotenv(dirname(__DIR__), $filename))->load();
} catch (Dotenv\Exception\InvalidPathException $e) {
    echo ".env for test is missing.";
    exit(1);
}

require_once 'bootstrap/app.php';

phpunit.xml

<?xml version="1.0" encoding="UTF-8"?>
<phpunit backupGlobals="false"
         backupStaticAttributes="false"
         bootstrap="tests/autoload.php" // here!
         colors="true"
         convertErrorsToExceptions="true"
         convertNoticesToExceptions="true"
         convertWarningsToExceptions="true"
         processIsolation="false"
         stopOnFailure="false">
    <testsuites>
        <testsuite name="Application Test Suite">
            <directory suffix="Test.php">./tests</directory>
        </testsuite>
    </testsuites>
    <filter>
        <whitelist processUncoveredFilesFromWhitelist="true">
            <directory suffix=".php">./app</directory>
        </whitelist>
    </filter>
    <php>
        <env name="APP_ENV" value="testing"/>
        <env name="CACHE_DRIVER" value="array"/>
        <env name="SESSION_DRIVER" value="array"/>
        <env name="QUEUE_DRIVER" value="sync"/>
    </php>
</phpunit>