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There is one single thing that defines a top-quality application: everything works. This may sound simplistic, but it's the bottom line. It doesn't matter how slick your user interface is, or how tricky the scripts are, or how sophisticated the material you are presenting; if everything in the project doesn't work exactly right, your work will be ignored—or worse, scorned—by others.
There's no secret to creating a great application that people will use and enjoy. Test the application and everything in it, again and again. Run everything through its paces several times and in different orders. Click every button, read and scroll every field, run every script. Show every dialog—and when you do, try every possible response button. Then get all your friends to do the same thing too.
That's it. Everything else I'm about to tell you is just commentary.
Most application errors and mistakes can be prevented by using a few simple testing techniques. Unfortunately, too many authors don't want to take the time to test their work adequately. While the fun may be in designing and scripting an application, remember that everyone else's opinion of it will be based on its performance. Users have high expectations of software these days, and they won't take time to figure out work-arounds to glitches. They'll just toss your application in the trash instead. Worse yet, they may avoid your work in the future based on one bad experience.
Try the following tips before releasing your stack. You may be surprised what you find. These techniques should ensure that your stack is as bug-free as it can be.
Pretend you just met your application in a crowded library and you don't know anything about it. Start clicking on (or typing into) everything. This doesn't just mean using the obvious buttons; it means, for example, clicking on locked fields that have scripts, and using all dialog boxes. Repeatedly bring up every dialog box until you have tried all possible responses to it, and don't forget "cancel", you need to account for a user wanting to bail out. Don't forget any controls that are hidden right now but that might be visible and used later; activate and use those too. Every button should do exactly as it is labeled (so choose your button names carefully.) Every script should interact cleanly with everything else without causing any errors.
Click outside any buttons or fields, right on the card itself, to be sure that nothing unexpected happens. If you've created any menus, systematically choose every single menu item, one at a time, to be sure it behaves right.
Set up some fake data with known content and test with that. Say you have a stack that opens a text file of numbers and totals them. Set up a text file and get a total with your hand calculator. Then run your application on the file and see if you get the same results. Or suppose you have a script that counts the number of times a text string occurs in another stack. Set up the other stack with a known number of repetitions of some text and then see if your script returns the right number. Too often scripters will suppose that if the script doesn't error when it runs, it must be okay. All that means is that you haven't any syntax errors; it doesn't say anything about the accuracy of the results when the script is done. Do tests on several different sets of known data. One set isn't enough; you need to account for all types of variation. In the first example above, you might create a text file containing all numbers except for one line of text. What happens when you run your script on that?
Once you've tried everything, and I mean everything, go back and try it all over again in a different order, preferably the wrong order. This will be incredibly educational. Don't fool yourself into thinking that your users will click all the buttons in the correct order, or even in any logical order (although your stack must present everything in an orderly way.) For example, what happens if a user decides to push a "calculate" button before they enter any data into some number fields? Does the app exit gracefully? Or does it error out half finished and leave the stack in an unpredictable state? What happens if users enter letters and other symbols that aren't numbers, or type in numbers in the wrong range (always test-enter numerical data as negative numbers at least once.) What happens to your other scripts when one script fails? Do you get a cascading failure when each succeeding handler looks for information that now doesn't exist, or exists in the wrong format?
Try your hardest to enter incorrect information into every field, enter data in the wrong format, and click every button out of logical order. While it is fine if this doesn't produce any usable results, it should definitely not produce any script errors either. If it does, you haven't done enough error-checking in your scripts. Don't think to yourself, "my stack is aimed at Mensa members with IQ's over 165 and they would never do that sort of thing, so I don't have to check for it." Trust me, they will. And you do.
Whenever you repair a script, no matter how small the change, start the testing process over again. There's no way around it; you have to be sure not only that the change in your script works correctly, but that it works correctly with everything else. You can use some judgment here. If you alter a script that displays information in a field, you probably only have to test that one script to be sure the display is correct. But if any other part of your application uses the data in that field later, then you need to re-test every other script that uses that field information. This may sound tedious, but it is the only way to avoid one of the main causes of errors: the interaction of different elements of your application.
Get three other people to run your application. This is hugely important. Never, ever release an application that no one else has used. If you don't know three other people, at least get one. If you know more than three, go for as many as you can rope into it. No two people will use your application the same way. Certainly no one will use it exactly the way you think they will. What they do with your app will tell you worlds about your work.
Choose people for testing who are as close as possible to the kinds of people who will be downloading and using your application. If your app is for children, use children to test it. If it's for anthropology professors, find some of those. If you don't know any anthropology professors then you can use your mother if you have to, but don't expect her to find all the anthropology mistakes. She will, however, probably still find a lot of generic errors having to do with application design.
Don't tell your testers what to do. This is a strict rule. Let them read any documentation or Read Me files you will supply with your application, but that's all. This is easier said than done, but remember that no one who downloads your software will have you around to give them verbal directions, and your tester shouldn't get any either. So limit yourself to watching, bite your tongue, and take a lot of notes. See what actions they choose to do first, where they get stuck, and how they look around in the app for help if they need it (you did put some help info in there, right?) This will tell you where your design isn't clear. Don't offer any advice unless the other person asks outright, and in that case give as little information as possible to get them back on track.
When they're done, you can ask them questions from your notes if you need to. Ask what they thought was good about the application and what was not so good. Pay attention to what they say and change your app if necessary. Try not to decide that they "didn't know what they were doing" and don't dismiss their comments as irrelevant. If your testers can't figure it out, probably no one else can either.
Run your stack on other people's computers, the more the better. If you are distributing cross-platform, you must test on as many variations of your target platforms as you can lay your hands on. How do the fonts look? Does the text overspill your buttons? Is the window too big to show up fully on a small laptop screen, or does it diminish to a postage stamp on a 27" monitor? How about speed? Is it acceptable on other computers? What flows smoothly on your state-of-the-art machine may stutter or crawl to a halt on an older one.
There's one last way guaranteed to find every possible obscure bug, hiccup, and glitch in your application: demo the stack to someone else. No matter how much testing you've done or how many people have gone over your work, if there's one obscure thing that can go wrong, it will gleefully manifest itself when you are trying to show your work to an important person—like a potential client, your latest love interest, or your anthropology professor. Those tiny little bugs that have been lurking under the paint layer just drooling for a chance to embarrass you will burst suddenly on screen, grinning and winking at each other. If you really, really want to find minute and obscure bugs, try showing off your software with as much pride as possible to someone important.
Avoid the "it's my baby" syndrome. It is tempting, after spending a lot of time with a stack, to want to leave it just as it is, simply because it's your baby. Be ruthless. Even babies are better for a little discipline. If something isn't appropriate for your application's purpose, take it out, no matter how cute it is or how much time you spent writing it. If your testers complain that fourteen repetitions of The Hamster Dance are a bit excessive, take it to the trash no matter how cute you think it may be. Remain constantly flexible. You don't have to change everything your testers say (after all, they really might not know what they're doing), but you should sure listen closely when they say it.
If you follow these testing guidelines, you can produce software that is consistently bug-free and reliable. The longer you test, the more people you test with, and the more repeatedly you test, the better your apps get. Even the simplest application can become pure art when it runs smoothly, behaves intuitively, and functions without errors.
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