There are three main areas to think about when testing a date field:
- What format will be accepted?
- How will the date be stored in the database?
- How will the saved date be displayed?
There are many ways to format a date when entering it into a form. One very important factor to consider is whether the system is expecting an American format: month, day, year; or a European format: day, month, year. For example, if I try to enter next Wednesday's date (12/13/2017) into some forms, it won't be accepted if the European format was what the form was expecting, since there is no 13th month. And if I enter July 4 into this form as 7/4/18, it may be saved to the database as April 7th.
Beyond the American/European formatting, there are still a myriad of ways to format dates. For example, will all four digits of the year be expected, or is it possible to put in just the last two digits? Will single-digit months and days be allowed, or is it necessary to precede those digits with zeroes, such as in 07/04/2018? What about spelling out the month, as in December 13, 2017? The developer should have a clear idea of what format or formats will be allowed, and should clearly communicate that to the user. For example, a tooltip such as "mm/dd/yyyy" can be used inside the field to help the user know what format to use. Regardless of whether the tooltip is in place, it is important to test with a number of different date formats to ensure that an appropriate error message is displayed when the expected format is not followed. Also be sure that the date itself is checked for whether it is a valid date; for example, 2/30/2016 should never be allowed, nor should 18/18/18.
Next, let's consider how the date will be stored in the database. Some developers, not knowing better, might store the date as a string, rather than as a datetime value. This is nearly always a bad idea for a number of reasons. If the accepted format changes over time, or if good validation was not in place in the past, there could be strings where the date is saved as "7/4/2017" and strings where the date is saved as "December 13, 2017". This will make it difficult to consistently display the data. Also, if the dates are stored as strings it will be difficult to sort correctly by ascending or descending date. "2017-12-13" might wind up coming before "3/7/2017" in an ascending sort. As testers, we should verify that the date is stored as a datetime value, and advocate for a change if it is not.
It's also important to look at how dates are displayed. When a user calls up saved information, they should be able to read the dates easily. "2017-12-13T00:00:00" might be the way the date is saved in the database, but a user won't be able to interpret this date quickly. The developer or designer should decide what date format would be best for display purposes and should stick to it consistently throughout the application. It's also important to consider what should happen in the case of bad data. What if there is a date saved in the database that says simply "December 13"? Should it be displayed as 12/13/0000? Should it not be displayed at all? These are important scenarios to consider and test.
There is one final consideration to make when testing date fields, and that is what the upper and lower limits of the date are. For example, are dates in the future ever allowed? What about dates from 100 years ago? Remember that the future and the past change every day! Let's say that our application doesn't allow dates in the future. That means that today, 12/13/17 is not an allowed date in our application. But by next Wednesday, 12/13/17 will be allowed. And of course, you may be reading this blog post years in the future, at which time 12/13/17 will be a thing of the past!