app/Http/Middleware/CollectCodeCoverage.php + tests/Feature/xCoverage.php Test code coverage middleware for Laravel 5.8+

CollectCodeCoverage.php

<?php

namespace App\Http\Middleware;

use Closure;

class CollectCodeCoverage {

    /**
     * Used for code coverage when running unit tests
     * @var array
     *
     * Register this in your Kernel file in the `$middleware` group!
     */
    static $routesTested = [];

    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request $request
     * @param  \Closure $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        $response = $next($request);

        if (app()->runningUnitTests()) {
            
            // Record code coverage
            static::$routesTested[] = [
                'url'    => $request->getRequestUri(),
                'name'   => optional(\Route::getCurrentRoute())->getName() ?? 'unknown',
                'method' => $request->getMethod(),
            ];

        }

        return $response;
    }
}

xCoverage.php

<?php

namespace Tests\Unit;

use Tests\TestCase;
use App\Http\Middleware\CollectCodeCoverage;

/**
 *
 * This test class needs to run LAST! PhpUnit will run them in alphabetical order;
 * this is the simplest way to do that
 *
 * Class xCoverageTest
 * @package Tests\Unit
 */
class xCoverageTest extends TestCase
{
    public function testCheckAllRoutesTested()
    {
        $missingRoutes = [];
        $routes = \Illuminate\Support\Facades\Route::getRoutes();
        $routesTested = CollectCodeCoverage::$routesTested;
        $list = collect($routesTested)->groupBy("name");

        foreach ($routes as $route) {
            $routeName = $route->getName();
            $hits = $list->get($routeName);

            foreach ($route->methods() as $method) {
                if ($method === 'HEAD') {
                    continue;
                } elseif ($hits === null || $hits->where("method", '=', $method)->count() === 0) {
                    $missingRoutes[] = $routeName . ' ' . $method;
                }
            }
        }

        asort($missingRoutes);

        $this->assertSame(0, count($missingRoutes), "Missing feature tests for Routes:\n" . implode("\n", $missingRoutes));
    }
}