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TDD is dead. Long live testing.

david.heinemeierhansson.com

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Re: TDD is dead. Long live testing.

#51

Post by jorgeleo »

erichmond wrote: post #39

I think a big part of the TDD phenomenon happened when the "big name" rails consulting shops insisted on using it. In consulting, I think this makes all the sense in the world. a) When you hand off code, you can demonstrably prove what you handed off works. b) You can take the business objectives of whoever you are consulting for and translate those into high level tests, which helps you stay focused. c) You get to c…

And... depends on what you are consulting on.

I live out of consulting, and my biggest projects is writing experimental consumer behavior simulation engines.

Is not that TDD does not have a value, it is just impractical

For once, since they are simulations, they are trying to predict the future, hence there is no right answer, there is the "Acceptable" answer, or the "Defensible" answer; so having a little test on the side that tells me that I am still producing the predicted result does not help much because there is no such thing as the correct predicted result

Sure I can do test to make sure I match the excel spreadsheet that I receive for spec, they would tell me that I copy the formulas correctly; but then, for seconds, I bring the results back and they test it with more real data, and they realize that we need to tweak 100s of different little formulas (which invalidate all the unit tests), change the order of a few of them, and introduced a couple of new ones (as I was told once "because I don't know what I was smoking that Tuesday, so we should use this new one"), and of course "can we have these changes for the end of the day?"

So it all unit tests are voided, make all those changes which are simple enough to be done in a couple of hours. And I am not going to know what is the correct result because there is no valid spreadsheet now, so I don't know in advance what is expected, hence I cannot write the test first

And wait until I try to tell them, the modifications will take 2 hours, but I need another 2 days to write the new set of unit tests, which since I wrote with the result of the modifications instead of before the modifications, they will not prove anything

Rinse and repeat 10s times a month for the last 4 years...

Re: TDD is dead. Long live testing.

#52

Post by tragic »

I can certainly sympathise with the abstinence-only pride and shame cycle. My projects typically start with a test-first approach, which evaporates when the clock starts ticking.

It seems to me, first of all, that there's a threshold of software complexity, beneath which writing tests is a net loss in time and productivity. If you have (as I often do) a couple of hundred LOC spread across a few files, with one or two models/views, then there is negligible gain to automated testing - by the time you've set up/torn down the test DB, you could have refreshed the page in a browser 5 times and seen all the error messages in there. I accept that this threshold can be hit very rapidly once you get towards a modest website, even; but my day job basically involves writing toy SPAs with a very simple API behind the scenes, built and then left chugging along until they're out of date, so I often sail under it.

A bigger anxiety I have about TDD is that, while there are no end of resources on using tests to drive software design, I haven't come across much about good design of tests (suggestions very much welcome). I rarely have confidence that my tests are any more use than assert_true(true). You test for the constraints you anticipate when you write the tests. I don't trust my code-fu that far, and so my tests inherit their author's impostor syndrome.

Re: TDD is dead. Long live testing.

#53

Post by typicalbender »

> The current fanatical TDD experience leads to a primary focus on the unit tests, because those are the tests capable of driving the code design (the original justification for test-first).

I don't agree with this blanket statement. For web apps at least, doing outside in TDD helps to create a nice ratio of integration tests to unit tests. By writing some high level happy path integration tests to drive functionality and then filling in with smaller functional units and unit tests I think is a better way of going about testing than starting with the units. TDD is a hard thing to get right and unfortunately when it goes wrong it can be very painful.

Re: TDD is dead. Long live testing.

#54

Post by twerquie »

> Test-first units leads to an overly complex web of intermediary objects and indirection in order to avoid doing anything that's "slow". Like hitting the database. Or file IO. Or going through the browser to test the whole system. It's given birth to some truly horrendous monstrosities of architecture. A dense jungle of service objects, command patterns, and worse.

This is DHH's central argument, he is once again defending his "there are only three places to put code" application design and the monolithic Rails architecture. We see him, time and time again, sniping at people who outgrow those patterns but still want to use Rails. People who do want fast and isolated unit tests, who want encapsulated, reusable service objects and people who are perhaps building something more complicated than a TODO list.

He goes as far as to subtly deprecate unit testing, something which is incredibly vital in a dynamic, loosely typed language such as Ruby, where monkey-patching other's code is more of a rule than an exception. In Ruby, unit tests stand in place of static compiler checks. I haven't heard a strong argument against them nor a replacement for them. The binary notion of "the whole application works" or "the whole application does not work" does nothing to quell the critics who say that Ruby and indeed Rails projects are brittle and difficult to refactor.

I love Rails and think it's a fine product, but I don't understand its leadership strategy, doggedly preserving web application design as it existed in 2004.

> "Rails 5 will be renamed to Basecamp. This will help to end confusion over which types of apps to build using Rails." @markbates

Re: TDD is dead. Long live testing.

#55

Post by bulte-rs »

Finally... acknowledgement from someone famous.

TDD is wonderfull in theory, just no missing edge-case detection; stuff you easily spot when using a "hybrid continuous testing methodology".

I'd say: Code away! Just make sure you have tests for the important stuff when you 'check in' your stuff.

Offtopic: I should become famous/respected in "the community" so I can push this kinda stuff forward faster internally.

Re: TDD is dead. Long live testing.

#56

Post by cageface »

shime wrote: post #40

where is this Rails train going? it used to be cool, but it looks like it's heading towards the chasm now. posts like this just encourage my opinion about the Merb merge with Rails being a disaster which helped Rails transform from "PHP in Ruby" to something beautiful to work with, while leading to self-destruction of Merb. Rails gained a lot of traction and is now abandoning any good decision Yehuda and other great…

I've felt the same way for a long time too. The Merb merge had more to do with soothing large egos and indulging some architecture astronauts than it did about making it a better framework for developers to work with. Now it feels a lot like the over-engineered Java frameworks it was designed to liberate us from.

Re: TDD is dead. Long live testing.

#57

Post by pixelmonkey »

I generalized DHH's conclusion re: TDD in my blog post, "XDDs: stay healthily skeptical and don't drink the kool aid":

http://www.pixelmonkey.org/2012/02/12/xdds

"I list one of my skills as “thought-driven development”. This is a little tongue-in-cheek; software engineering over the last few years has developed a lot of “XDDs,” such as test-driven development, behavior-driven development, model-driven development, etc. etc.

“Thought-driven development” doesn’t actually exist, but by it, I simply mean: perhaps we should think about what we’re doing, rather than reaching for a nearby methodology du jour..."

Re: TDD is dead. Long live testing.

#58

Post by room271 »

I mostly agree with this post, but I do wonder whether the difficulty of doing unit testing the OP describes is partially related to their use of RoR and the associated (complex) object-oriented design.

Re: TDD is dead. Long live testing.

#60

Post by mattgreenrocks »

tragic wrote: post #52

I can certainly sympathise with the abstinence-only pride and shame cycle. My projects typically start with a test-first approach, which evaporates when the clock starts ticking. It seems to me, first of all, that there's a threshold of software complexity, beneath which writing tests is a net loss in time and productivity. If you have (as I often do) a couple of hundred LOC spread across a few files, with one or two…

> I haven't come across much about good design of tests (suggestions very much welcome)

Growing Object-Oriented Software Guided By Tests is worth a start. The authors use TDD, but that shouldn't put you off from learning the theory of separating concerns enough to write fewer tests.

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