How can PHP developers test and verify the accuracy of their date calculations, especially when dealing with edge cases like the end of the month?

When dealing with date calculations in PHP, especially around edge cases like the end of the month, developers can test and verify the accuracy of their calculations by using built-in functions like `strtotime()` and `date()`. By creating test cases that cover various scenarios, including leap years and different month lengths, developers can ensure their date calculations are correct. Additionally, using PHP's DateTime class can provide more flexibility and accuracy in handling dates.

// Example code snippet to verify date calculations accuracy
$date = '2023-02-28'; // Input date
$nextMonth = date('Y-m-d', strtotime('+1 month', strtotime($date))); // Calculate next month
echo $nextMonth; // Output: 2023-03-28