Demonstrates That Month Addition Results in Overflow And How To Fix

CarbonNextMonthEndOfMonthTest.php

<?php

namespace Tests\Unit;

use Tests\TestCase;

class CarbonNextMonthEndOfMonthTest extends TestCase
{
    public function setUp(): void
    {
        \Carbon\Carbon::setTestNow('2019-10-31');
    }

    /** @test */
    public function it_gets_the_wrong_last_day_of_the_end_of_the_next_month_because_of_overflow()
    {
        $end_of_month = \Carbon\Carbon::now()->addMonth()->endOfMonth()->format('d/m/y');

        $this->assertEquals('31/12/19', $end_of_month);
    }

    public function it_gets_the_last_day_of_the_end_of_the_next_month()
    {
        $end_of_month = \Carbon\Carbon::now()->addMonthsNoOverFlow()->endOfMonth()->format('d/m/y');

        $this->assertEquals('30/11/19', $end_of_month);
    }
}