TDD: The Bad Parts - Matt Parker

Ғылым және технология

Slides: www.slideshare.net/Pivotal/tdd...
TDD, the savior of bad code, the promise of a better world. And yet… so many teams have tried TDD and failed. It’s a deceptively simple practice that actually requires a good deal of craftsmanship and skill to wield effectively. Through explanations and examples, we’ll examine a number of common problems teams face, including:
Test Coupling
Many folks our community promote the idea that unit testing means having a test file for every production class, and a test for every public method. And yet this tightly couples tests to the underlying design patterns of the codebase, and makes it hard to refactor. We’ll look at a way to minimize the surface area of your testing and intentionally define an interface between your tests and production code.
Mocking (Hammer of the Gods)
Mockito (and libraries like it) have created very simple and powerful ways for Java developers to create and use test doubles in their tests. And yet those libraries have also led to a good deal of misunderstanding and misuse of test doubles. We’ll examine the five types of test doubles, their roles, and when they’re applicable - and we’ll also look at the common problems developers run into misusing these tools and concepts.
Death by a Thousand Flakes
Outside-in behavior driven development is a commonly used practice. And yet we have too often conflated “outside” with ”GUI” - with disastrous results. We’ll look at the problems this has caused, including slow test suites, flaky test suites, upside down testing pyramids, and more.
Test Suite Bankruptcy
When all of these bad practices combine, they lead to one place: test suite bankruptcy. We’ll examine a case study of a team that, with the best intentions, applied all of these practices together for the better part of a year, and was forced to declare test suite bankruptcy at the end. We’ll talk about the tell-tale signs that you are approaching bankruptcy, and what you should do if you ever find yourself in that situation (or inheriting that situation from others).
SpringOne Platform 2016
Speaker: Matt Parker; Engineering Director, Pivotal.

Пікірлер: 42

  • @ulissemini5492
    @ulissemini54925 жыл бұрын

    when he said BDD i thought he meant Bug Driven Development, thats what i do.

  • @soyphea8697

    @soyphea8697

    5 жыл бұрын

    peep 😂

  • @jensBendig

    @jensBendig

    3 жыл бұрын

    That is not the worst Idea: Whenever you find a bug: Look for the systematic that has allowed it. Often they come by Design

  • @thygrrr

    @thygrrr

    2 жыл бұрын

    Don't we all?

  • @SoneiiraGF
    @SoneiiraGF5 жыл бұрын

    When you talk about refactoring, I feel the same thing. I write my unit tests and my production code is covered. But, if I need to change a lot of things in Refactor step, probably my design is not well designed! In my opinion that is the point. Martin Fowler said, "TDD is a tool, and people should learn how to use it well." And it's true. TDD is just a technique, but it won't take any decisions for you. Damage is caused by people. With or without TDD, if you take good decisions, your design will be great but, if you make bad decisions, your design will be bad. Actually, I practice BDD and TDD and at the moment the experience is being great. When I need to change a lot of things in Refactor step, I try to learn what I could be done to avoid it. And to be honest, I feel very confident because the Integration and E2E test (BDD) ensure the behavior. Thank you for the talk. Cheers

  • @soymichelo75

    @soymichelo75

    3 жыл бұрын

    nice thoughts, there is a talk from Sandro Mancuso (Does TDD lead to good design?) that complements your thoughts :D take a look, you might like it as well. Cheers

  • @kallaskaspar
    @kallaskaspar5 жыл бұрын

    I strongly agree that outside-in testing does not mean GUI testing. Every time I mention BDD then people associate it with Selenium. Every time I mention unit testing then people associate it with the smallest of possible units which is a single class or a method. I believe the best bang for your buck lies in-between and that boundary is to be strategized per project. As I write my applications using semi-DDD and semi-CQRS then my B(T)DD boundary tends to be the execution of a command.

  • @nikosc
    @nikosc5 жыл бұрын

    This is a very good talk, all the principles talked here are to the point.

  • @PaulGaida69
    @PaulGaida693 жыл бұрын

    Awesome talk. Thanks. Especially the fact, that you see only the slides, so you can follow the topic.

  • @zzzfortezzz
    @zzzfortezzz5 жыл бұрын

    Thank god you're here. I've just started learning TDD recently, and I noticed about the "test every classes and methods". I felt something bad about this, but I didn't know how to fix that, I knew there's something wrong. Came your talk, you cleared my confusion and saved hairs on my head. Thank you very much!!!

  • @kenji5497

    @kenji5497

    4 жыл бұрын

    He lost his hair so you dont have to

  • @phyzix_phyzix

    @phyzix_phyzix

    2 жыл бұрын

    Unit in unit testing means unit of functionality not unit of code. You should only test your public interface not every class / method. In other words, only test the functionality not the implementation. You end up covering a lot more with a lot less tests. And your tests tend to not break everytime you change the code.

  • @BryonLape
    @BryonLape5 жыл бұрын

    Would really like to see some actual examples.

  • @JuanPareles
    @JuanPareles5 жыл бұрын

    fantastic talk. Thanks for upload it

  • @albertoeyo1675
    @albertoeyo16756 жыл бұрын

    Fantastic talk, every developer who makes tests should listen talks like this.

  • @portlyoldman
    @portlyoldman18 күн бұрын

    Not sure why I was recommended this as it’s quite old. I’m trying to focus on the content but i keep giggling to myself like a ten year old as it somehow makes me think of General Grievous 🤪🤣

  • @dannybolick4783
    @dannybolick47834 жыл бұрын

    Did I miss it, or did he never finished the story about the company and their unit tests? (outside of just saying they were still around).

  • @TheKrazyKat89

    @TheKrazyKat89

    4 жыл бұрын

    Yup. He said "what went wrong? We'll come back to this as the end", and then... he only said they're still around.

  • @CoffeeWithSteve
    @CoffeeWithSteve4 жыл бұрын

    Good talk but I think a lot of people misunderstand refactoring. Refactoring does not always mean modify existing code. The O in SOLID stands for "Open for extension, closed for modification". Once a piece of code is in production you shouldn't modify it. You can extend it or replace it, but not change it. This means new tests, new classes, and new methods. Quite often it also means new abstractions to make for a smoother transition to the new code. The temptation is to go in and simply change the existing implementation because you find some error, or the code is difficult to understand. This will often lead to failing tests so now there's a temptation to change the tests. None of that is advisable. Instead put your eye toward REPLACING the existing code with new code. It's cheap to do, you'll have more confidence in it, and it leads to more abstractions.

  • @thatoneuser8600

    @thatoneuser8600

    2 жыл бұрын

    There's a drawback to abstraction: indirection and code clutter that makes code harder to understand. Instead of following SOLID completely, follow the Rule of Three: only refactor when you see three similar pieces of code, that way you allow some duplication in order to make sure you have a good, substitutable abstraction that has already been proven to be reused. Don't just create a 1:1 interface for every class; that's just speculative generality that you most often will never need or use. An interface should always have at least three implementors And you do need to refactor every now and then, even abstractions like renaming methods. As development continues, the design will get worse and worse. You can't just rely on upfront design as the upfront design is hardly ever right the first time. Thus, when you add a new feature but the codebase isn't convenient in a way that easily allows you to add functionality, you improve the design of the existing codebase to make it cleaner/easier to understand, and therefore making it faster and easier to implement the new feature.

  • @sergeykholkhunov1888
    @sergeykholkhunov18882 жыл бұрын

    I don't take the point about test coupling. Yes, it forces me to change tests when refactoring, but I think it's kinda normal. If you change "unit", you need to change "unit test". Otherwise, the unit test becomes integration test. As Uncle Bob says, TDD is a discipline, and there are some arbitrary boring rules in most disciplines. Also, when you remove test coupling, you trade understandability on flexibility.

  • @pawelbartoszek9758
    @pawelbartoszek97587 жыл бұрын

    Great talk. Matt could you post a link to a TDD open source project you mentioned during questions?

  • @VMwareTanzu

    @VMwareTanzu

    7 жыл бұрын

    A Ruby example: github.com/moonmaster9000/board_app A Java example: github.com/moonmaster9000/RegisterApp

  • @roberttonne
    @roberttonne4 жыл бұрын

    I think at this time the definition should be changed to UTDD, U is for Unit, makes things less confusing

  • @nathansnow
    @nathansnow2 жыл бұрын

    Strepsils... The main takeaway I got was Strepsils

  • @researchandbuild1751
    @researchandbuild17514 жыл бұрын

    LOL that swallowing sounds...reminds me of that Silicon Valley episode..Im still convinced most software project failures are mainly just lack of domain knowledge. Without domain knowledge you'll never get it right. Because customers are horrible at explaining what they need in a form that a developer can understand.

  • @John-Dennehy

    @John-Dennehy

    4 жыл бұрын

    Or developers are terrible at understanding the customers needs?

  • @Rockem1234
    @Rockem12344 жыл бұрын

    This is more of bad practices in testing. how is it TDD related?

  • @HoD999x
    @HoD999x3 жыл бұрын

    my suggestion is to always ask yourself: "how can i do this with less work"

  • @SoaringSimulator
    @SoaringSimulator3 жыл бұрын

    Look outside of what you want to discover, is not form J. WILK. Is an Oriental common practice.

  • @ChristopherSalisburySalz
    @ChristopherSalisburySalz3 жыл бұрын

    Good lord!! Can we take it easy on new slang in programming for a while! Dummy, spy, stub, mock, fake, BDD, TDD, and on and on!! It is getting so damn ridiculous with all the crap we have!

  • @superscatboy
    @superscatboy4 жыл бұрын

    My theory is that if it's obvious what your tests should be and they're simple to construct, use TDD. If they're non-obvious or a nightmare to construct, TDD might not be the way to go.

  • @TheInimicus

    @TheInimicus

    2 жыл бұрын

    If you don't know what your tests should be, that means you don't know what your application should be. In that case, do a PoC, see if it is what you want, then erase that and do TDD the normal way.

  • @christianwulf8224
    @christianwulf82242 жыл бұрын

    I do not understand, why a controller test with a mocked service is useless. Matt says the controller does not contain logic. Sure, in this example it is trivial. But you write tests for designing a good Software architecture and for ensuring future changes do not break the rest of your logic. Furthermore, if the Controller does not contain logic, why do we need it to implement? Hence, Controller tests are useful. Especially if you want to test permissions, the correct URLs with HTTP verbs and the returned model structure including the potentially different status codes (404, 201, 204, 400,...).

  • @matthijshebly
    @matthijshebly3 жыл бұрын

    The coughing is REALLY offputting

  • @coljackdripperofburp
    @coljackdripperofburp3 жыл бұрын

    ok, now show us a code example how to test behaviour instead of classes ... (he can't). Bad talk. He points out some problems with the TDD cargo cult, but proposes only very vague solutions.

  • @travissmith2127

    @travissmith2127

    3 жыл бұрын

    I can't think of a better definition of "behavior" than a classes public methods, so I don't know what the solution to that could possibly be. Same with the mock of the service,it's either you're going to use the real service or your not, there isn't a middle ground

  • @matthijshebly
    @matthijshebly5 жыл бұрын

    Drinking noises are REALLY annoying in talks...

  • @einfacherkerl3279

    @einfacherkerl3279

    5 жыл бұрын

    drinkin noises?

  • @matthijshebly

    @matthijshebly

    5 жыл бұрын

    @@einfacherkerl3279 Yes, you know, noises that result from drinking loudly close a microphone

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