A simple way of testing that your Lumen commands are scheduled exactly when and how you expect. This approach does not trigger commands to actually execute, which is what a lot of other suggestions do.

ConsoleSchedulingTest.php

<?php

use App\Console\Kernel;
use Carbon\Carbon;
use Illuminate\Console\Scheduling\Event;
use Illuminate\Console\Scheduling\Schedule;
use Illuminate\Support\Collection;

class ConsoleSchedulingTest extends TestCase
{
    
    /**
     * Verify that my-command-name is scheduled to run at 7AM ET in production.
     */
    public function testCommandIsScheduledToRunAt7am() {
        $date = Carbon::today()->timezone('America/Toronto')->setTime(7,0);
        $dueEvents = $this->getScheduledEventsForCommand('my-command-name', $date);

        $this->assertCount(1, $dueEvents, 'Command is not scheduled for expected time');

        /**
         * @var \Illuminate\Console\Scheduling\Event $event
         */
        $event = $dueEvents->first();

        $this->assertTrue($event->runsInEnvironment('production'));
    }
    
    /**
     * For scheduled jobs, the fully qualified class name should be referenced.
     */
    public function testJobIsScheduled() {
        $scheduledJobEvents = $this->getScheduledEventsForCommand(MyJob::class);
        $this->assertCount(1, $scheduledJobEvents);
    }

    /**
     * @param string $commandName
     * @param Carbon|null $atTime
     * @return Collection
     */
    private function getScheduledEventsForCommand(string $commandName, Carbon $atTime=null): Collection {
        # configure scheduled through Kernel
        new Kernel($this->app);

        /**
         * @var Schedule $schedule
         */
        $schedule = $this->app->get(Schedule::class);

        return collect($schedule->events())->filter(function(Event $event) use($commandName, $atTime){
            if(!str_contains((string)$event->command, $commandName) && strcmp((string)$event->description, $commandName) !== 0) {
                return false;
            }

            # optionally filter out events that are not due at the given time.
            if($atTime !== null) {
                Carbon::setTestNow($atTime);
                return $event->isDue($this->app) && $event->filtersPass($this->app);

            } else {
                return true;
            }
        });
    }

}

i'm using Laravel 6.0, any idea why $schedule->events() return empty?

UPDATE: I originally stated that this was for Laravel, but it was actually only tested in Lumen. Sorry, I run both Laravel and Lumen and often forget which one I am using. I will update this if I ever adapt it to Laravel.