Compare Carbon without milliseconds

Rounding seems risky as you don't know if it will round up or down.

You could format to the same as your database?

$this->assertEquals(now()->addDays(14)->format('Y-m-d H:i:s'), $user->some_date);

but it seems odd that this should be necessary?

Thought of that but it makes the test a bit ugly and as you said, it's rather strange this happens.

This happens in a package I'm building by the way. Using Orchestra.

I would suggest whenever you are testing to use Carbon's setTestNow helper so that you are working with known datetimes rather than begin sensitive to when the test is being executed

public function it_saves_the_correct_datetime()
{
    Carbon\Carbon::setTestNow('2020-05-01 15:00:00');
    $user = User::create();

    $this->assertEquals(now()->addDays(14), $user->some_date);
}

Remember to clean-up in the tearDown method.

If you don't like that, then maybe consider the isSameX methods, choosing X depending on the level of granularity you want:

public function it_saves_the_correct_datetime()
{
    Carbon\Carbon::setTestNow('2020-05-01 15:00:00');
    $user = User::create();

    $this->assertEquals(now()->addDays(14)->isSameSecond($user->some_date));
}

Or add your own assertions to the project.

For example you could make your own DateAssertionsTrait add add it to your TestCase.

public function assertSameDay($expected, $actual, $message = null)
{
      $this->assertEquals(
             Carbon::make($actual)->toDateString(),
             Carbon::make($expected)->toDateString(),
             $message
       );
}


public function assertSameDate($expected, $actual, $message = null)
{
      $this->assertEquals(
             Carbon::make($actual)->toDateTimeString(),
             Carbon::make($expected)->toDateTimeString(),
             $message
       );
}

Usage:

$this->assertSameDate(now()->addDays(14), $user->some_date); 
// or
$this->assertSameDate('2020-04-23 00:00:00', $user->some_date);

// or if you don't care about the time: 
$this->assertSameDay('2020-04-23', $user->some_date); 

I solved by converting to timestamp, which knows nothing of microseconds...

$this->assertEquals($actual->timestamp, $expected->timestamp);