I personally have kind of moved away from TDD over the years, because of some of these reasons: namely, that if the tests match the structure of the code too closely, changes to the organization of that code are incredibly painful because of the work to be done in fixing the tests. I think the author's solution is a good one, though it still doesn't really solve the problem around what you do if you realize you got something wrong and need to refactor things.

Over the years I personally have moved to writing some of the integration tests first, basically defining the API and the contracts that I feel like are the least likely to change, then breaking things down into the pieces that I think are necessary, but only really filling in unit tests once I'm pretty confident that the structure is basically correct and won't require major refactorings in the near future (and often only for those pieces whose behavior is complicated enough that the integration tests are unlikely to catch all the potential bugs).

I think there sometimes needs to be a bit more honest discussion about things like: * When TDD isn't a good idea (say, when prototyping things, or when you don't yet know how you want to structure the system) * Which tests are the most valuable, and how to identify them * The different ways in which tests can provide value (in ensuring the system is designed for testability, in identifying bugs during early implementation, in providing a place to hang future regression tests, in enabling debugging of the system, in preventing regressions, etc.), what kinds of tests provide what value, and how to identify when they're no longer providing enough value to justify their continued maintenance * What to do when you have to do a major refactoring that kills hundreds of tests (i.e. how much is it worth it to rewrite those unit tests?) * That investment in testing is an ROI equation (as with everything), and how to evaluate the true value the tests are giving you against the true costs of writing and maintaining them * All the different failure modes of TDD (e.g. the unit tests work but the system as a whole is broken, mock hell, expensive refactorings, too many tiny pieces that make it hard to follow anything) and how to avoid them or minimize their cost

Sometimes it seems like the high level goals, i.e. shipping high-quality software that solves a user's problems, get lost in the dogma around how to meet those goals.

It's difficult to ignore the solution that is staring my brain in the face and pretend to let it happen organically. I know that I will end up with a worse design too, because I'm a novice at TDD and it doesn't come naturally to me. (I'd argue that I'm a novice at everything and always will be, but I'm even more green when it comes to TDD)

I have no problem writing unit tests, I love mocking dependencies, and I love designing small units of code with little or no internal state. But I cannot figure out how to let go of all that and try to get there via tests instead.

I don't think that I'm a master craftsman, nor do I think my designs are perfect. I get excited at the idea of learning that the way I do everything is garbage and there's a better way. If I ever learn that I'm a master at software development, I'll probably get depressed. But I don't think my inability to get to a better design via TDD is dunning-kruger, either.

I want to see the light.

But, I'm here as a you-can-do-it-to. You might not think you want to but I'm so glad I DID manage to get there.

Feel free to ignore because I respect that everyone's experience differs. But the real problem is that there are few good step by step tutorials that teach you from start to competent with TDD. Couple that with the fact that it takes real time to learn good TDD practices and the vast majority of TDDers in their early stage write too many tests, bad tests, and tightly couple tests.

Just as it's taken you time to learn programming - I don't mean hello world, but getting to the competent level with coding you're at today, it'll take a long time to get good with TDD. My case (ruby ymmv) involved googling every time I struggled; lots of Stack Overflow; plenty of Confreaks talks; Sandi Metz' POODR...

Like the OP says - at different stages in the learning cycles you take different approaches because you're better, it's more instinctive to you. I thought I understood the purpose of mocks/doubles, until I actually understood the purpose of mocks/doubles. When used right they're fantastic.

The key insight that everyone attempting TDD has to grok, before all else, is that it's about design not regression testing. If you're struggling to write tests, and they're hard to write, messy, take a lot of setup, are slow to run, too tightly coupled etc. you have a design problem. It's exposed. Think through your abstractions. Refactor. Always refactor. Don't do RED-GREEN-GOOD ENOUGH ... I did for a long time. It was frustrating.

This is a good post. Don't dismiss TDD because you're struggling. Try to find better learning tools and practice lots and listen to others who are successful with it.

It's true that sometimes fads take hold and we can dismiss them as everyone doing something for no reason. But cynicism can take hold too and we can think that of everything and miss good tools and techniques. TDD will help you be a better coder - at least it has me. If your first response to this post was TDD is bullshit, give it another try.

It's true that nothing forces your to refactor - but I think wanting that is a symptom of treating TDD as a kind of recipe-based prescriptive approach. It is not a reflection of the nature of TDD as a practice or habit.

It's a subtle difference, but important:

A recipe says "do step 3 or your end result will be bad"

A practice says "do step 3 so you get better at doing step 3"

Has anyone else solved this chicken and the egg dilemma?

I used to be an instructor for a living, and I kind-of equated lectures to waterfall and exercises to XP. There is even a semantically analogous term in teaching research, problem-based learning (each word corresponds to the respective word in test-driven development - cool, right?). Is there anyone else who sees these analogues, or am I completely crazy here?

As a developer that often prefers tests at the functional level, the primary benefit of tests for me is to get faster feedback while I am developing.

https://www.youtube.com/watch?v=URSWYvyc42M

But one detail ran counter to my personal practice.

I don't believe that "symmetrical" unit tests are a worthy goal. I believe in testing units of behavior, whether or not they correspond to a method/class. Symmetry leads to brittleness. I refactor as much as possible into private methods, but I leave my tests (mostly) alone. I generally try to have a decent set of acceptance tests, too.

Ideally, you specify a lot of behavior about your public API, but the details are handled in small private methods that are free to change without affecting your tests.

When I'm teaching TDD, the kata I have everyone go through is a simple order system.

The requirements are something like:

A user can order a case of soda

The user should have their credit card charged

The user should get an email when the card is charged

The user should get an email when their order ships

If the credit card is denied, they should see an error message

(etc....)

This way they can think about abstracting out dependencies, an IEmailService, a ICreditCardService, etc. There are no dependencies for a Roman Numeral converter.

All his classes ended in "er".

he's not writing object oriented software, he's writing imperative software with objects.

The observation that "[s]ome teachers deal with this problem by exhorting developers to refactor rigorously with an appeal to virtues like discipline and professionalism" reminds me of E. O. Wilson's remark that "Karl Marx was right, socialism works, it is just that he had the wrong species."

If test-driven design were the programming panacea its proponents sometimes seem to make of it, Knuth would have written about it in TAOCP. Instead Knuth advocates Literate Programming. TDD seems to attract a cult-like following, with a relatively high ratio of opinion to cited peer-reviewed literature among proponents.

TDD as this is commonly understood seems to me like the calculational approach to program design (c.f. Anne Kaldewaij, Programming: the derivation of algorithms), only without the calculation and without predicate transformers. Still it can be a useful technique.

There is no "right" way to program. This was evident from the beginning, when Turing proved the unsolvability of the halting problem. (Conventions are another matter.)

I'd like TDD to be more than just another way to relearn those old rules, especially if we arrive at the same conclusions on a circuitous path. Perhaps the old design rules, object patterns, etc. have to each be integrated with a testing strategy, e.g. if you're using an observer you have to test it like this and if you refactor it like that you change your tests like so.

The general rules are easy to understand and your post makes perfect sense but once you formulate your new design approach you'll have to find a way to teach it precisely enough to avoid whatever antipattern is certain to evolve among the half-educated user community, which usually includes myself and about 95% of everyone else.

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I haven't designed code the way he's advocating, but I have attempted TDD by starting with the leaves first. Here are the downsides to that:

1) Sometimes you end testing and writing a leaf that you you don't end up using/needing.

2) You realize you need a parameter you didn't anticipate. EG: "Obviously this patient report needs the Patient object. Oh crap I forgot that there's a requirement to print the user's name on the report. Now I've got get that User object and pass it all the way through".

Maybe these experiences aren't relevant. As I said, I haven't tried to "Fake It Until You Make It".

I still follow the old Code Complete method: think about the problem, sketch it out, then finally implement with unit tests. The results are the same, and it's a lot less painful than greenhorn-TDD.

So now, they reformalize exactly the so "rigid" ISO9001 they were trying to throw down.

What an irony.

But that 'test' word really puts people in the wrong frame of mind at the outset.

Thank you! Details of this post aside, this gave me an Aha! moment and I feel like I'm finally leaving the WTF mountain.