[411111111111111]

Another reason why it's so hard to actually say "tdd does/doesn't work" is that everyone has their own idea what it is.

Its like everything in software engineering: everyone has an opinion, few have actually tested theirs with performant and stable production deployments

[marginalia_nu]

I think, additionally, it's domain specific.

There are problems where TDD is actually a decent approach. If you have solid requirements beforehand, and your problem does reduce to small bite sized units with trivial state, then it's amazing for producing code that doesn't surprise you when you run it.

There are problems where it really really really isn't. Things where there is ambiguity in the expected outcome. Language processing for example is fairly difficult to tackle with TDD. There is no simple state, there is no unambiguous expected outcome. Whether "jump" is a verb or a noun non-trivially depends on the context, and it may even ambiguous. The correctness of such code is a percentage value, not a boolean.

For context, when I debug the keyword extraction for my search engine crawler, I'm looking at test output that looks like this: <https://memex.marginalia.nu/pics/frog-text.png> (blue are individual keywords, red are potential n-grams).

[agentultra]

Isn't the acronym, test driven development?

All that means to me is that when we start a project we think about what it means for an implementation to be correct and write a test. If we agree on the specification, the test, then a passing implementation means that we have implemented it correctly -- for that particular test.

One of the challenges of using unit tests for this kind of testing is, as you say, difficult with modelling continuous values.

It is also difficult because the "proof" is so small and trivial. You need thousands of examples to gain some confidence... and for even moderately complex software this can not be enough.

Unfortunately, the path to writing good tests and verifying software requires a bit of mathematical vocabulary and reasoning which many developers are too shy to learn or outright hostile towards ("I've never needed no stinking math, this is programming!").

My point is: as long as you're driving the development of your software using testing, I think you're practising TDD.

[necovek]

Unfortunately, it's hard to be put into a position where you can apply one, let alone multiple new approaches to software development on a team developing a large application for a long time (say at least 2 years). You'll have team churn, you'll have requirements churn, you'll have understanding of methodologies and practical realities change, etc.

So by "testing their (opinions)", I usually understand people to mean that they've been on a project where they've enjoyed working on something in a particular way (people always underestimate what someone is simply enjoying doing, I have no idea why). I understand that almost nobody is able to compare and contrast two significantly different approaches, let alone establish things like incident rates or cost of improvement and such resulting from application of those approaches (because there's no reference point).

What we do need is for all developers to contribute to setting up a foundation dedicated to establishing software development methodology quality, and then have that set up a dozen teams of 4-8 engineers working on a dozen longish problems (6-36 months) with different methodologies, and then aggregate and analyze results in 12 years. All the engineers would have market-rate salaries, so we'd all have to be chipping in monthly :D

I mean, just imagine where we'd be if we've done that in 2010? (probably at the same place, but just maybe not!)

[falcolas]

Or TMTOWTDI.

Or there's hidden assumptions that differentiate between a Google solution and a coffee shop solution.

Performant... stable... both have ridiculously variable definitions based on who you talk to. That alone is probably enough to get your 10 Sr. developers to provide different solutions.

[parasubvert]

I don’t think the assumptions are hidden. There is plenty of literature with a reasonable discussion of the range of definitions of performance and scale. It’s that people aren’t even looking for them. It’s about “Team Red vs Team Blue”. Or whatever buzzword needs to be on your resume alongside leetcode for the next interview. NoSQL vs SQL, FP vs OOP. Can’t get my raise if I’m building coffee shop solutions!

The counter to TMTOWTDI is a set of principles and discipline, at least within a team or a project. Not to outright reject the alternatives, but to recognize the power of consistent behaviour and prioritization of tradeoffs, to try to counter the brand allegiances.

[falcolas]

> I don’t think the assumptions are hidden.

And yet in the very article we're talking about, there's no explanation of what assumptions the author is operating within.

I'll even go so far to say that most technical articles omit the assumptions - because it's boring content and is less likely to engage the readers.

[necovek]

Most senior engineers I talk to would give you "conditional answers" on those, and I wouldn't be surprised at all.