Migrate DateTime to Carbon

Carbon is an excellent library for working with dates and times in PHP. It's being used by Laravel as the default date-time library.

But it's not only syntax sugar wrapped around the DateTime class. It provides a reliable way to test your code that depends on exact dates and times.

The Carbon package brings a practical API to work with dates:

// the DateTime
$date = (new \DateTime('today +20 day'))->format('Y-m-d');
// the Carbon way
$date = \Carbon\Carbon::today()->addDays(20)->format('Y-m-d')

No need to remember strings like "+days", "-weeks", or "a month". You can use the method API directly:

$date = \Carbon\Carbon::now()->addMonths(2);

Reliable Tests Under Control

Where does the Carbon package bring real value? Tests that depend on the exact date. Native DateTime depends on the timezone of the server or commiter. If they get into conflicts, "+1 day" can yield different results and make tests fail. Then, we have to find out if that's a false positive or a real problem. That's not the tests we want to debug.

Instead, we can mock the "now" directly:

// Don't want this to happen so mock now
Carbon::setTestNow(Carbon::createFromDate(2000, 1, 1));

// comparisons are always done in UTC
if (Carbon::now()->gte($internetWillBlowUpOn)) {

// Phew! Return to normal behavior

That way, we make a date constant through our test suite for any developer or server.

How to Migrate DateTime to Carbon

To make this work, we have to replace our DateTime instances with Carbon instances:

-$start = (new \DateTime('today +1 day'));
+$start = \Carbon\Carbon::today()->addDays(1);

-$end = (new \DateTime('today +30 days'));
+$end = \Carbon\Carbon::today()->addDays(30);

That's where Rector comes in. The next release will ship a new carbon set that will handle migration for you:



use Rector\Config\RectorConfig;

return RectorConfig::configure()
    ->withPreparedSets(carbon: true);

This way, your tests will become reliable, and you won't have to wait for another developer to trigger CI at the "right time" again.

This set is still fresh, so if it misses some cases, let us know.

Happy coding!