Is it legally negligent to not use unit testing

Question

Is anyone aware of any legal precedents where the lack of unit testing in an application has lost someone a case Or where someone has not been deemed negligent despite a lack of unit testing in an application. Is there any highly regarded alternative to unit-testing that enables programmers to objectively demonstrate a committment to software quality.

Edit: For example in medicine you can use in your defence that your approach is one that is regarded as acceptable by a substantial and well regarded group of other doctors.

Answer 1

Unit testing is only a (very valid) alternative to test your code, it can't and could not be a legal requirement.

For example, you could prove some properties of a piece of code using a denotational semantic and some techniques that found their justification on well-founded relations, complete partial orders and fixed-point theorems.

Answer 2

Legal is between you and whoever will pay for your software

If the contract said that you will do unit testing and you don't, then you're liable. It depends on every software and every agreement you make. When I buy Windows for critical software applications (laugh, laugh, it DOES happen), no one makes sure they unit tested everything

Answer 3

A lawyer could probably find out for you, but it would probably be expensive.

In general, there's no liability in software. How good or bad a thing this is is debatable, but I haven't found a piece of software yet that doesn't disclaim liability. (There was a case where a tax preparation program several years ago had a problem, and the company actually recompensed people to some extent. I know of no other exceptions.)

Liability would normally only come about in embedded software, since a manufacturer is frequently liable for the behavior of a device, and the software is part of the device. In that case, demonstrating that sound software engineering practices were used might be useful, but I would be astonished to learn that failing to use unit tests would be considered negligence. (There is also, at least in the US, a concept of "strict liability", which means somebody's completely to blame, no excuses possible. It's been applied to navigational maps, but if you want to know for what else you need to consult a lawyer or do your own research.)

So, what I'm saying is that I don't know of any cases, it sounds dubious to me, I am not a lawyer, and this is not legal advice.

Answer 4

Mate, if your a real developer getting paid you should already know why unit tests are valuable in maintaning quality and other merits. I certainly might not sue you but i would fire you. Asking such a question demonstrates that you are a cowboy without a professional attitude in deliverying a quality product.

Answer 5

Unit testing, in a formal sense, is a relatively new concept in software (I'd guess less than 10 years old). Prior to that, some components and modules were tested, but it was more important that the overall system be tested.

Generally, the law lags behind contemporary practices by quite awhile. It takes a long time for laws, codes, and cases to establish a precedent. It would be very surprising to me if there is any consensus in law about a relatively new approach like unit testing.

Answer 6

Unless you are IBM you. Should not be in a position to gurantee your code is defect free.as strange as it sounds this is the clients responsibility.

Answer 7

I have worked on softwares which are critical applications that are installed only when the seller gives a buyer a complete list of testing done on the software and undersigned physically by the testers and the QA. this involves even if there is small unit which undergoes minor modification.

Answer 8

User testing can be illegal in some cases (stackoverflow.com: what-legal-issues-surround-unit-testing-database-code-closed), because you can't allowed to do some things with personal data, for example in a database you wanted to include in your test.

In defense of a negligence lawsuit, an accused programmer might use extensive unit testing in his defense. If a contract specified unit testing, but none was conducted, then there would be cause for breach of contract.

Unit testing is not enough to reveal every possible fault, and there is not an ISO standard for it yet. A naive court might be convinced that it indicated neglect, but it is surely not founded upon a great body of legal precedent.

Answer 9

Unit testing is a good idea in general, but the field of software engineering has a long way to go until it's a standard practice that people can be sued for not doing. There are many cases where unit tests are simply not appropriate. Unless it's explicitly mentioned in a contract, there shouldn't be an expectation that unit testing will be used for a product.