I want to know that,does BDD just work in acceptance test level? If not, does it work in unit test level as well? Does BDD have any suggestion For Unit tests?
thank you
BDD is just a way of defining the specifications for an area of functionality. The idea is to bridge the gap between technical and non-technical people by using human readable syntax of some kind and to use specific examples to define the desired behaviour rather than talking in the abstract. As such it is a tool to help people work together and define the business' requirements for the new functionality. This is the primary point of BDD. Not testing.
The definitions that come out of BDD are however, useful for acceptance testing as they define the expected behaviour that was agreed upon. As such many great tools like cucumber are available to facilitate automation of these scenarios to cut down on your testing time.
With regard to using BDD for something like unit tests, the idea of using BDD and non-technical descriptions is to help involve non-technical people. If there are no non technical people involved in the creation of your unit tests (which I guess is the most likely case) then why bother with it? Technical people can read unit tests that are properly written, just fine. The unit tests that you're writing will come out of the functionality that is described by your BDD scenarios anyway.
However, if there is some technical detail of what you're working on that you're having trouble describing, and your team are comfortable working in a BDD way then definitely give the non-technical language and specific examples approach a go. I just wouldn't bother using the the human readable language version of the example in your unit test.
Edit: After reading xmojmr 's comment about your question, I can absolutely see the benefit of using BDD tools and syntax to make your unit tests more readable/easier to plan out, but I think this is quite different from BDD in general, which is more about bridging a communication gap.
BDD actually started at the class level. The first incarnation of JBehave was a replacement for JUnit that avoided the word "test". It was only later that the system-level stuff came along after Dan North explained mock objects to Chris Matts, an analyst at the time who was learning how to code.
These days, even unit testing frameworks don't insist that you start your test methods with the word "test", and the frameworks for the dynamic languages are pretty much derived from RSpec, which was a port of JBehave's early functionality to Ruby anyway.
So, yes, it's perfectly possible to do BDD at that level.
Of course, alannichols is right in saying that the audience is different, being non-technical.
So why would you want to do BDD?
As Dan says in that first link, it turns out that talking about behaviour is more useful than talking about tests. In BDD, we just avoid the word test. We prefer talking about examples and how things should behave rather than pass or fail.
By having conversations around the desired behaviour of a system or class, and providing examples of that behaviour, you can explore it more easily than when you're talking about testing.
However, because it's a non-technical audience, I find it's enough to put the "given, when, then" in comments. You can see an example here. You don't need an explicit BDD tool.
If you can't find another dev to talk about the behaviour with, I suggest you find a rubber duck.
Related
I am coming from a TDD mindset into BDD. I understand that using BDD is to focus on ensuring the behaviours and business goals of software are being met.
What confuses me is that if I start using BDD in place of TDD, it seems I'm not able to test at such a low-level. For example, when writing a test with a TDD mindset, I might test that properties have been attached to the scope:
it('should attach properties to scope', function () {
expect(MainCtrl.items.length).toEqual(1);
});
In doing this, another developer knows the assignment to scope was expected and required for future use, saving them some debugging should they have removed the assignments or changed defaults etc.
This example doesn't define a behavior so can't be considered BDD. Of course, I could rewrite the test description to make it more behavior orientated, such as, "when the page loads, setup properties for later use so the user can do so and so..." but this seems too abstract.
Is it a done-thing to use both TDD and BDD at the same time? Have BDD available to define the behaviors for all parties involved in the project (including non-technical) and TDD specifically for developers?
Short answer, yes.
However, the distinction between BDD and TDD is not as you've mentioned and I'd like to clear up what "ensuring the behaviours and business goals of software are being met" really means :)
BDD precedes, envelopes and goes beyond the development stage. BDD is far more than a syntax and not just a change from the word "test" to the word "should". BDD is actually a paradigm to writing software that involves the end-to-end business. This page explains that:
BDD is a second-generation, outside–in, pull-based, multiple-stakeholder, multiple-scale, high-automation, agile methodology. It describes a cycle of interactions with well-defined outputs, resulting in the delivery of working, tested software that matters.
BDD starts with deliberate discovery, where a group of people get together and flesh out the details of a story using scenarios. The group of people is typically made up of 1+ of each of the following disciplines: product, development and QA - also referred to as the three amigos. This exercise precedes development and is very good at identifying defects before you even start development and it creates better specifications through a shared understanding.
Once you have a good story with good scenarios, you can drive development using an outside-in testing approach:
This means you start with the acceptance test (avoid the UI if you can), and as you drive development into the system, you employ TDD at the integration and unit levels for things like your services and domain objects. Here you can choose any syntax you like, and what you have used above with "should" is fine.
If you're using Javascript, we created an open source tool called Chimp to make the process of outside-in testing easy.
Finally, I recommend you look at the following links:
Specification by Example
Shallow Depth of Test
I a bit familiar with rspec [Ruby] and specs [Scala]. Yesturday I passed a tutor for Cucumber. What I disliked about Cucumber is that additionally to describing scenarios (like you would do with spec- or xUnit-style testing) you have to implement extra layer of indirection: translating scenario steps into ruby expressions. For me creating unnecessary (?) extra layers of indirection feels like "heavy-weight" J2EE-way, not like "light-weight" ruby way. Is understandability by "domain experts" the only advantage of Cucumber? Or is there some non-obvious (technical?) advantages for developer/tester as well?
BDD, from a practical standpoint, is highly synonymous with TDD. Rspec is a BDD test framework, as well as Cucumber.
That stakeholders can read and understand Cucumber acceptance specifications is certainly a key advantage, but this fact alone really doesn't get at the real benefit of Cucumber. Your features and scenarios ought to grow somewhat in specificity as the work being done for them moves through the value stream of your team's development cycle.
Some teams may have an analyst scoping out work at the beginning of the cycle. Sometimes this analyst writes gherkin acceptance specifications, but whoever writes the first draft, you would expect them to be fairly coarse grained. They may not cover every un-happy path.
As the developers take up the work, they often discover edge cases and missing scenarios. At this point they can touch base with the analyst, and the results of such conversations should be written into the cucumber features.
In my experience the testers have cultivated an even more critical eye, and thus it is not uncommon to see them add even more scenarios and features. The testers may also uncover defects, which should be added to the cukes to protect us from regression.
The point is that, in addition to providing executable documentation for our code, Cucumber also provides a repository for the state of the team's conversations vis a vis the features being developed.
There is certainly extra overhead to all of this. However, it's worth considering how much overhead is already in your team's process, which Cucumber might serve to streamline. I find that Cucumber helps reduce the amount of thrash that happens in communication about features both within and outside of the team room.
I should also mention that cucumber is intended as full-stack acceptance testing, and therefore should be less fine-grained, relative to your unit tests. And cucumber is not a good substitute for unit and integration tests. I also would never recommend using cucumber to verify aesthetic aspects of your app's UI. Just use it to validate the actions which a user might take when using your app.
Cucumber is designed to help engage business stakeholders in refining developers' and testers' understanding of the system by collaborating to create scenarios that everyone can understand.
The act of engaging business stakeholders pays off because everyone gets a better understanding, they start sharing the same language and carrying that language into the code (see Domain Driven Design's "Ubiquitous Language"), which can lead to better estimates, appreciation of scope, conversations around options for achieving the same goal, etc. etc.
There are certainly other ways of achieving the goals. For instance, on our C# project we talk through the scenarios, write them on a wiki then implement them using a little custom Domain Specific Language rather like this one. The same thing could be done in Ruby.
BDD is the process of learning the places where we thought we knew what we were doing, but it turned out we were wrong - the discovery of ignorance. With Feature Injection and unit-level examples, this happens at multiple levels of granularity, all the way up to the project vision itself. It tends to pay back for itself, but you don't need a BDD framework to do BDD.
The conversations in BDD are the important bits, not the tool you use to capture them (I helped write JBehave and still believe this is true). Automating regression tests is also important to cut down the manual effort which rises as the codebase grows, and Cucumber, DSLs and other BDD tools give you this as a very nice by-product which also help you trace, and drive out, the shared understanding.
Edit: I should mention that the reuse of steps is also important, but it doesn't make much difference whether you use a BDD framework or a DSL for that. It does make the difference between a DSL and just procedurally mimicking every user interaction.
It depends what you want to achieve.
Cucumber adds overhead, can be tricky to get used to, takes time to master.
If you want your domain experts to be able to read your tests, you should definitely give it a try.
On the other hand, if developers are the only people reading your tests, you can probably stick to rspec/unit-test/etc. and write your integration tests in those frameworks. However you might achieve more readable high level documentation by using cucumber.
See for example rspec 2 core features' descriptions in cucumber.
In my shop, there isn't much familiarity with unit testing in general, but I'd like to get into it, at the very least, as a proof of concept. Would it be a crazy idea to simply use the Visual Studio function Create Unit Tests on my small (~500 lines) code base and show the concept that way?
Not a crazy idea at all, just know what you should expect to get from that approach.
If you just want to show how to unit test existing code, which is what Roy Osherove calls TAD (Test After Development), it is a quick and easy way to show what kind of things should be tested.
If you are unit testing because you are interested in moving towards TDD, then your approach may serve to confuse, rather than enlighten. Trying to show someone TDD by adding unit tests to existing code defeats the purpose, in my opinion.
Rather, I would look into something (like SpecFlow) that attempts to focus on the spirit of TDD, which is that you're writing a specification (or requirement) in your test code, before you write the real code to make it work.
A light switch flipped for me when I realized that a unit test written before code could actually be my very detailed requirement. It was self-documenting, and as long as the unit test (spec) was written correctly, then my working code was guaranteed to meet the requirement!
If you agree with this, you may want to take a look at the Bowling Game Kata. I found it very helpful for introducing unit testing and TDD concepts.
No this is not crazy at all and is IMHO a great idea.
The only way a group or company can get into a culture of Unit Testing is if someone starts using it. If you don't it's unlikely that the existing people who aren't familiar with the concept will.
A potentially even better idea would be to grab a couple bugs on your plate and write the unit tests which reproduce the failure. Demo the tests catching the real bug and validating the solution. I find that's often fairly compelling for people who aren't familiar with the concept of unit testing.
My question is same as the title. I have not done Test driven development yet,I have performed unit testing and I am aware of testing in general but I hear it is much advantageous to follow TDD?. So should I opt for it everytime or are there some preconditions... i just need to know some basic or important requirements when i should opt for TDD. Sorry if this question is too trivial.
I would say whenever you are coding for a project. By this I mean where you are hoping to produce code that will be used by people. This is basically all code apart from research where you are learning and discovering new techniques.
Even if you think the project is just a small one often things spiral up out of control without care. You wil be glad for the tests when you find yourself having to refactor a big sprawl of code.
Also note that tdd isn't just about testing. It is a methodology of development that encourages you to create clean and solid designs.
As you are starting out tdd everything. Once you have more experience then perhaps you can back off and determine when to not tdd.
IMHO if you are not comfortable with TDD, trying to apply it in projects where you will need to interact/use legacy code it's much more complex than applying it in a project from scratch. In fact, there is a whole book about this.
HTH
My advice would be to use unit testing as often as possible.
Caveat: In my experience TDD works best when working with technologies you already have some experience with. It's often hard to write test assertions if you do not know exactly what the desired result looks like (For example, try writing the test for an ASP.NET MVC action method if you never wrote an action method in your entire life). In those cases you're probably better off writing unit tests after implementing the code.
If I am developing something without a user interface, I always use TDD these days. After all, you have to test the software. You can either do the extra work and do TDD, or you can do the extra work and cludge together a user client just for testing. The former tests more completely and in a more repeatable fashion.
Doing TDD against user interface code, on the other hand, hasn't really delivered much value for me. For various business reasons I'm restricted to Visual Studio out of the box for my work, and "recording" tests with VS is a huge time sink, especially when you have to re-record them if you change the UI. I do TDD for the business logic behind the UI, but not the UI itself.
I know that unit testing is desirable, and I am interested in doing unit testing. The only problem is I have no idea how, or even where to start really. So my question is: How do I learn about and start unit testing? Specifically I frequently write Java code in NetBeans and C# code in Visual Studio and am interested in what tools to use and how to get my feet wet. Can anyone offer any advice for an absolute unit testing n00b?
I know that there are a lot of somewhat similar questions out there but I am less interested in why and more interested in how.
Try to read on StackOverflow, tag unit-testing :)
Is Unit Testing worth the effort?
How to make junior programmers write tests?
What is unit testing?
How do you know what to test when writing unit tests?
Another entry point would be the tags junit and nunit
There are lots of question dealing this.
If you're searching books about Unit Testing, try this thread:
Good C# Unit testing book. There the famous Kent Beck book is mentioned, "Test Driven Development By Example".
It's worth reading!
Good luck!
This Tutorial for writing JUnit tests in NetBeans should give you an idea how unit testing is done technically. NUnit for C# works pretty much the same.
For an advanced view of how to integrate unit testing into you daily development, the standard reference is Kent Beck's "Test Driven Development By Example". Here's a broad overview.
If you really want to understand unit testing (and get hooked), try it out, it should only take a few hours!
First, I recommend downloading a unit testing framework, such as NUnit (if you want to start with .NET / C#).
Most of these frameworks have online documentation that provides a brief introduction, like the NUnit Quick Start. Read that documentation, then choose a fairly simple, self-contained class for which you are responsible. If you can, try to choose a class that:
Has few or no dependencies on other classes - at least not on complex classes.
Has some behavior: a simple container with a bunch of properties won't really show you much about unit testing.
Try writing some tests to get good coverage on that class, then compile and run the tests.
Unit testing is simple to learn and hard to master (apologies for the cliché, but it is appropriate here), so once you've done this, start reading around: for example, guerda has provided several excellent links in another answer to this question.
Start small.
Unit testing (and automated testing in general) isn't a silver bullet, doesn't always apply to every situation and can be a bit of a culture shock. That said, if you're writing software that you're selling or that your company relies on, I highly recommend adopting it. You'd be surprised how many professional development shops don't.
First, get comfortable the mechanics of creating and running unit tests with your development tools.
Then, start with a new (preferably small, but not necessarily trivial) class or method that you want to test. Writing tests for existing code has its own challenges, which is why you should start with either something brand new or something that you are going to rewrite.
You should notice that making this class or method testable (and therefore reusable) has an impact on how you write the code. You should also find that thinking about how to test the code up front forces you to think about and refine the design now instead of some time down the road "when there's more time". Things as simple as "What should be returned if a bad parameter is passed in?". You should also feel a certain amount of confidence that the code behaves exactly the way you expect it to.
If you see a benefit from this exercise, then build on it and start applying it to other parts of your code. Over time, you'll have confidence in more and more of your software as it becomes more provably correct.
The hands on approach helped get my head around the subject better than a lot of the reading material and helped fill in the gaps of things I just didn't understand. Especially where TDD was concerned. It was counter-intuitive until I actually tried it.
Find-a-bug-write-a-test
The next time you find a bug in your code base, before fixing it, write a test. The test should fail. Then, fix the bug. The test should pass.
If the test doesn't pass, there's either a bug in your test, or a bug in your fix.
A person will never find that bug in your code again. The unit tests will find it (and faster than a person can).
This is definitely a small start, but it gets you into testing. Once you've got the hang of it, you'll probably start writing more tests, and eventually get a knack for how code will fail and which tests you need (for example: a test for every business rule).
Later in your progression you setup a continuous integration server, which makes sure your codebase is always solid.
A good start is to buy a good book where you can read about unit-testing.
I have a tips on a book called "Software testing with visual studio team system 2008" and it takes you trough the basics stuff and background to more higher levels of unit-testing and practises.
Check out The Art of Unit Testing by Roy Osherove, it's a good book for beginners since it starts at the very beginning.
I would recommend reading Michael Feathers' "Working Effectively with Legacy Code". Old code often ends up being code that's hard to Unit Test. Feathers' book is a great guide in how to refactor your code to the point that unit tests are a snap to write.
Not exactly an answer to the question you asked, but might be a missing step between where you are, and where you need to be to implement some of the answers others have given.