I read the Wikipedia article on scenario testing, but I am sad to say it is very short. I am left wondering: are scenario tests a collection of sequential unit tests? Or, perhaps, like a single multi-step unit test? Do many frameworks support scenario tests, or are they covered by unit testing?
If they have nothing to do with automation, what are they?
I don't think there's any fixed relationship between the number and distribution of tests and scenario tests.
I think the most common code-representation of a scenario is a specific set of business data required to support a specific story (scenario). This is often provided in the form of database data, fake stub data or a combination of both.
The idea is that this dataset has known and well-defined characteristics that will provide well defined results all across a given business process.
For a web application I could have a single web-test (or several for variations) that click through the full scenario. In other cases the scenario is used at a lower level, possibly testing a part of the scenario in a functional test or a unit test. In this case I normally never group the tests by scenario, but choose the functional grouping of tests I normally use for unit/functional tests. Quite often there's a method within "Subsystem1Test" that is called "testScenario1" or maybe "testScenarioInsufficientCredit". I prefer to give my scenarios names.
In addition to korsenvoid's response, in my experience scenario based testing will often be automated as it will be included in regression testing. Regression testing is regularly automated as to do it manually does not scale well with regular releases.
In commercial software, good examples of scenerio tests are tutorials included with the user documentation. These obviously must work in each release or be removed from the docs, and hence must be tested.
While you can carry out scenario testing using sequenced unit tests, my guess is that it is more common to use GUI based automation tools. For example, I use TestComplete in this role with a scripting framework to good effect. Scenario tests are typically carried out from a user/client perspective which can be difficult to accurately replicate at a unit level.
IMHO, scenario testing is a testing activity, as opposed to development activity ; hence it's about testing a product, not unit(s) of that product. The test scenario are end-to-end scenarios, using the natural interfaces of the product. If the product has programmatic interfaces, then you could use an unit test framework, or Fitnesse.
Related
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about programming within the scope defined in the help center.
Closed 5 years ago.
Improve this question
In the context of Agile software development, what's the difference between User Acceptance Test (UAT), Test Case Scenario and Functional Test?
The members of the team I am part of, they consider the three things as different, but I see them as exactly the same thing.
In fact, all of them are designed having the end user in mind
There's a lot of different sorts of testing. Many of them overlap. Many use the same tools. Many are specializations of other more general terms. Often they blur together. People argue about the terminology all the time.
You're correct that they all have the end user in mind, but they are different.
User Acceptance Test
This is a specific form of an acceptance test where a subject-matter expert, ideally the client or their representative, tests the software. This is in addition to functional and acceptance testing done by QA. It's designed to simulate, as closely as possible, an actual end-user using the software; the tester is asked to perform a bunch of common tasks with the new system, but not given specific instructions nor coaching on how to do it.
For example, if you were creating a site for an airline, they might be asked to register, login, book a flight, make a payment, check in, check their flight status, and so on.
Functional Test
This is blackbox testing done by the QA role. It verifies the thing does what it's supposed to do; you give it inputs, you check the outputs. Typically this is testing against the specification and/or requirements document.
"Functional" here doesn't refer to code functions, but that the system functions as expected. Testing specific functions is unit testing.
They can be purely functional, "when I do X I get Y". They can be about resource use, "when I do X it uses no more than Y memory/time". Or about error checking, "when I give it garbage I get a well formed error". Anything that validates it meets the requirements.
Test Case Scenario
Sounds like Scenario Testing: this uses stories, similar to user stories, that help a tester work through a complicated testing scenario. Scenario testing tests complicated combinations of things which might arise during actual use and often cut across multiple systems.
An example of a test scenario might be: "in the middle of processing the system runs out of disk space; verify an admin is notified, that processing resumes once space is cleared, and that no data is lost".
A User Acceptance Test might use Scenario Testing.
These are my rules of thumb:
Unit testing: does this one function work?
Integration testing: do the functions work together?
Functional testing: does it function as required?
Acceptance testing: is it acceptable to the client?
Regression testing: does it still work like it used to?
User Acceptance Testing is having business users trying out your app.
There is also an Acceptance Testing done by QA when they check the new functionality - you can call it a Story Acceptance Testing to distinguish between these. These are not necessarily Functional Tests (could be Security, Performance testing, etc.).
Test Case is a number of steps to check a small piece of functionality. It has Prerequisites, Steps, Expected Result, Actual Result. This is one of the ways of carrying out Functional Testing. Others could be: exploratory testing, checklists.
Test Scenario - steps that cover a bigger picture. Often they cover cases of how real users would use the app. But these are carried out by QA team.
Functional Test - a test that checks the functionality as opposed to e.g. Performance. This can be a unit test as well, but since this terminology is mostly used by QA - when people talk about them they usually mean Functional System Test.
Note, that different authorities may use different definitions of the same terms. Check out Holes in testing terminology: Test Types and Test Levels. Since it's impossible to find the one true terminology it's more important that you use terms consistently within your team even if they are used differently in other companies and teams.
User acceptance testing is a process that obtains confirmation that a system meets agreed customer/product manager requirements.
Functional Testing is actual functionality test of the software there can be many different types of testing but in simple word testing the functionality what is should be expected.
The test scenario is the high level of testing cases when the first classification of module testing then module dividing into a scenario and at last small and specifical test steps with expected result says test cases, so the test scenario is group test cases with limited to specific functionality and module.
So I'm looking into introducing a more extensive testing process and I was reading about Functional Testing. I've worked with Scenario Testing before, but I'm fairly new to the term Functional Testing.
It seems that the two are synonymous, however I've not been able to find any information on whether they are synonymous or whether one is a subcategory of the other or whether they are two separate things. I've searched on stackoverflow, I've read the wiki pages for both, I've read some blogs on both and some university pages on both and can't seem to find the answer.
So as the title says; is there a difference between Scenario Testing and Functional Testing or are they synonymous?
Scenario testing got introduced with BDD (Behavorial driven development). So, basically while testing a single scenario, you will most of the times have multiple functional testing scenarios. The aim of Scenario testing is to test the scenario as a whole and BDD promotes it majorly.
Let me try to elaborate it with an example. So, say that a project is following BDD and the scenario to be tested is usually specified in the form of Acceptance Criteria as below:
As an authenticated user, in order to withdraw cash, I should be able to use the ATM.
So, in this case to test this Scenario, you would need multiple functional tests to run. Listing few of them below:
Authenticate user
Enter valid cash to withdraw
Cash withdrawn
This just one flow and there will be multiple positive and negative functional tests involved in this scenario which need to be designed.
So, we can say that a scenario consists of multiple functional tests. However, they are not synonyms since Scenario testing can also include scenarios related to performance, usability testing etc. and is not just restricted to functional testing.
Hope I could resolve your query to certain extent.
Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 7 years ago.
The community reviewed whether to reopen this question 6 months ago and left it closed:
Original close reason(s) were not resolved
Improve this question
Are functional testing and integration testing the same?
You begin your testing through unit testing, then after completing unit testing you go for integration testing where you test the system as a whole. Is functional testing the same as integration testing? You still taking the system as a whole and testing it for functionality conformance.
Integration testing is when you test more than one component and how they function together. For instance, how another system interacts with your system, or the database interacts with your data abstraction layer. Usually, this requires a fully installed system, although in its purest forms it does not.
Functional testing is when you test the system against the functional requirements of the product. Product/Project management usually writes these up and QA formalizes the process of what a user should see and experience, and what the end result of those processes should be. Depending on the product, this can be automated or not.
Functional Testing:
Yes, we are testing the product or software as a whole functionally whether it is functionally working properly or not (testing buttons, links etc.)
For example: Login page.
you provide the username and password, you test whether it is taking you to home page or not.
Integration Testing:
Yes, you test the integrated software only but you test where the data flow is happening and is there any changes happening in the database.
For example: Sending e-mail
You send one mail to someone, there is a data flow and also change in database (the sent table increases value by 1)
Remember - clicking links and images is not integration testing. Hope you understood why, because there is no change in database by just clicking on a link.
Hope this helped you.
Functional Testing: It is a process of testing where each and every component of the module is tested. Eg: If a web page contains text field, radio botton, Buttons and Drop down etc components needed to be checked.
Integration Testing: Process where the dataflow between 2 modules are checked.
This is an important distinction, but unfortunately you will never find agreement. The problem is that most developers define these from their own point of view. It's very similar to the debate over Pluto. (If it were closer to the Sun, would it be a planet?)
Unit testing is easy to define. It tests the CUT (Code Under Test) and nothing else. (Well, as little else as possible.) That means mocks, fakes, and fixtures.
At the other end of the spectrum there is what many people call system integration testing. That's testing as much as possible, but still looking for bugs in your own CUT.
But what about the vast expanse between?
For example, what if you test just a little bit more than the CUT? What if you include a Fibonacci function, instead of using a fixture which you had injected? I would call that functional testing, but the world disagrees with me.
What if you include time() or rand()? Or what if you call http://google.com? I would call that system testing, but again, I am alone.
Why does this matter? Because system-tests are unreliable. They are necessary, but they will sometimes fail for reasons beyond your control. On the other hand, functional tests should always pass, not fail randomly; if they are fast, they might as well be used from the start in order to use Test-Driven Development without writing too many tests for your internal implementation. In other words, I think that unit-tests can be more trouble than they are worth, and I have good company.
I put tests on 3 axes, with all their zeroes at unit-testing:
Functional-testing: using real code deeper and deeper down your call-stack.
Integration-testing: higher and higher up your call-stack; in other words, testing your CUT by running the code which would use it.
System-testing: more and more unrepeatable operations (O/S scheduler, clock, network, etc.)
A test can easily be all 3, to varying degrees.
I would say that both are tightly linked to each other and very tough to distinguish between them.
In my view, Integration testing is a subset of functional testing.
Functionality testing is based on the initial requirements you receive. You will test the application behaviour is as expected with the requirements.
When it comes to integration testing, it is the interaction between modules. If A module sends an input, B module able to process it or not.
Integration testing - Integration testing is nothing but the testing of different modules. You have to test relationship between modules. For ex you open facebook then you see login page after entering login id and password you can see home page of facebook hence login page is one module and home page is another module. you have to check only relationship between them means when you logged in then only home page must be open not message box or anything else. There are 2 main types of integration testing TOP-DOWN approach and BOTTOM UP approach.
Functional Testing - In functional testing you have to only think about input and output. In this case you have to think like a actual user. Testing of What input you gave and what output you got is Functional testing. you have to only observe output. In functional testing you don't need to test coding of application or software.
In a Functional testing tester focuses only Functionality and sub functionality of application. Functionality of app should be working properly or not.
In integration testing tester have to check dependency between modules or sub-modules.Example for modules records should be fetching and displayed correctly in another module.
Integration Test:-
When Unit testing is done and issues are resolved to the related components then all the required components need to integrate under the one system so that it can perform an operation.
After combining the components of the system,To test that whether the system is working properly or not,this kind of testing is called as Integration Testing.
Functional Testing:-
The Testing is mainly divided into two categories as
1.Functional Testing
2.Non-Functional Testing
**Functional Testing:-
To test that whether the software is working according to the requirements of the user or not.
**Non-Functional Testing:-
To test that whether the software satisfies the quality criteria like Stress Test,Security test etc.
Usually,Customer will provide the requirements for Functional Test only and for Non Functional test,Requirements should not be mentioned but the application necessarily perform those activity.
Integration testing It can be seen as how the different modules of the system work together.
We mostly refers to the integrated functionality of the different modules, rather different components of the system.
For any system or software product to work efficiently, every component has to be in sync with each other.
Most of the time tool we used for integration testing will be chosen that we used for unit testing.
It is used in complex situations, when unit testing proves to be insufficient to test the system.
Functional Testing
It can be defined as testing the individual functionality of modules.
It refers to testing the software product at an individual level, to check its functionality.
Test cases are developed to check the software for expected and unexpected results.
This type of testing is carried out more from a user perspective. That is to say, it considers the expectation of the user for a type of input.
It is also referred as black-box testing as well as close-box testing
Checking the functionality of the application is generally known as functional testing, where as the integration testing is to check the flow of data from one module to other.
Lets take example of money transfer app.Suppose we have page in which we enter all the credentials and if we press transfer button and after that if we getting any success, Then this is functional testing. But in same example if we verify the amount transfer then it is integration testing.
Authors diverge a lot on this. I don't believe there is "the" correct interpretation for this. It really depends.
For example: most Rails developers consider unit tests as model tests, functional tests as controller tests and integration tests as those using something like Capybara to explore the application from a final user's perspective - that is, navigating through the page's generated HTML, using the DOM to check for expectations.
There is also acceptance tests, which in turn are a "live" documentation of the system (usually they use Gherkin to make it possible to write those in natural language), describing all of the application's features through multiple scenarios, which are in turn automated by a developer. Those, IMHO, could be also considered as both, functional tests and integration tests.
Once you understand the key concept behind each of those, you get to be more flexible regarding the right or wrong. So, again IMHO, a functional test could also be considered an integration test. For the integration test, depending on the kind of integration it's exercising, it may not be considerate a functional test - but you generally have some requirements in mind when you are writing an integration test, so most of the time it can be also considerate as a functional test.
What is the real difference between acceptance tests and functional tests?
What are the highlights or aims of each? Everywhere I read they are ambiguously similar.
In my world, we use the terms as follows:
functional testing: This is a verification activity; did we build a correctly working product? Does the software meet the business requirements?
For this type of testing we have test cases that cover all the possible scenarios we can think of, even if that scenario is unlikely to exist "in the real world". When doing this type of testing, we aim for maximum code coverage. We use any test environment we can grab at the time, it doesn't have to be "production" caliber, so long as it's usable.
acceptance testing: This is a validation activity; did we build the right thing? Is this what the customer really needs?
This is usually done in cooperation with the customer, or by an internal customer proxy (product owner). For this type of testing we use test cases that cover the typical scenarios under which we expect the software to be used. This test must be conducted in a "production-like" environment, on hardware that is the same as, or close to, what a customer will use. This is when we test our "ilities":
Reliability, Availability: Validated via a stress test.
Scalability: Validated via a load test.
Usability: Validated via an inspection and demonstration to the customer. Is the UI configured to their liking? Did we put the customer branding in all the right places? Do we have all the fields/screens they asked for?
Security (aka, Securability, just to fit in): Validated via demonstration. Sometimes a customer will hire an outside firm to do a security audit and/or intrusion testing.
Maintainability: Validated via demonstration of how we will deliver software updates/patches.
Configurability: Validated via demonstration of how the customer can modify the system to suit their needs.
This is by no means standard, and I don't think there is a "standard" definition, as the conflicting answers here demonstrate. The most important thing for your organization is that you define these terms precisely, and stick to them.
I like the answer of Patrick Cuff. What I like to add is the distinction between a test level and a test type which was for me an eye opener.
test levels
Test level is easy to explain using V-model, an example:
Each test level has its corresponding development level. It has a typical time characteristic, they're executed at certain phase in the development life cycle.
component/unit testing => verifying detailed design
component/unit integration testing => verifying global design
system testing => verifying system requirements
system integration testing => verifying system requirements
acceptance testing => validating user requirements
test types
A test type is a characteristics, it focuses on a specific test objective. Test types emphasize your quality aspects, also known as technical or non-functional aspects. Test types can be executed at any test level. I like to use as test types the quality characteristics mentioned in ISO/IEC 25010:2011.
functional testing
reliability testing
performance testing
operability testing
security testing
compatibility testing
maintainability testing
transferability testing
To make it complete. There's also something called regression testing. This an extra classification next to test level and test type. A regression test is a test you want to repeat because it touches something critical in your product. It's in fact a subset of tests you defined for each test level. If a there's a small bug fix in your product, one doesn't always have the time to repeat all tests. Regression testing is an answer to that.
The difference is between testing the problem and the solution. Software is a solution to a problem, both can be tested.
The functional test confirms the software performs a function within the boundaries of how you've solved the problem. This is an integral part of developing software, comparable to the testing that is done on mass produced product before it leaves the factory. A functional test verifies that the product actually works as you (the developer) think it does.
Acceptance tests verify the product actually solves the problem it was made to solve. This can best be done by the user (customer), for instance performing his/her tasks that the software assists with. If the software passes this real world test, it's accepted to replace the previous solution. This acceptance test can sometimes only be done properly in production, especially if you have anonymous customers (e.g. a website). Thus a new feature will only be accepted after days or weeks of use.
Functional testing - test the product, verifying that it has the qualities you've designed or build (functions, speed, errors, consistency, etc.)
Acceptance testing - test the product in its context, this requires (simulation of) human interaction, test it has the desired effect on the original problem(s).
The answer is opinion. I worked in a lot of projects and being testmanager and issuemanager and all different roles and the descriptions in various books differ so here is my variation:
functional-testing: take the business requirements and test all of it good and thorougly from a functional viewpoint.
acceptance-testing: the "paying" customer does the testing he likes to do so that he can accept the product delivered. It depends on the customer but usually the tests are not as thorough as the functional-testing especially if it is an in-house project because the stakeholders review and trust the test results done in earlier test phases.
As I said this is my viewpoint and experience. The functional-testing is systematic and the acceptance-testing is rather the business department testing the thing.
Audience. Functional testing is to assure members of the team producing the software that it does what they expect. Acceptance testing is to assure the consumer that it meets their needs.
Scope. Functional testing only tests the functionality of one component at a time. Acceptance testing covers any aspect of the product that matters to the consumer enough to test before accepting the software (i.e., anything worth the time or money it will take to test it to determine its acceptability).
Software can pass functional testing, integration testing, and system testing; only to fail acceptance tests when the customer discovers that the features just don't meet their needs. This would usually imply that someone screwed up on the spec. Software could also fail some functional tests, but pass acceptance testing because the customer is willing to deal with some functional bugs as long as the software does the core things they need acceptably well (beta software will often be accepted by a subset of users before it is completely functional).
Functional Testing: Application of test data derived from the specified functional
requirements without regard to the final program structure. Also known as
black-box testing.
Acceptance Testing: Formal testing conducted to determine whether or not a system satisfies its acceptance criteria—enables an end user to determine whether or not to
accept the system.
In my view the main difference is who says if the tests succeed or fail.
A functional test tests that the system meets predefined requirements. It is carried out and checked by the people responsible for developing the system.
An acceptance test is signed off by the users. Ideally the users will say what they want to test but in practice it is likely to be a sunset of a functional test as users don't invest enough time. Note that this view is from the business users I deal with other sets of users e.g. aviation and other safety critical might well not have this difference,
Acceptance testing:
... is black-box testing performed on a system (e.g. software, lots of manufactured mechanical parts, or batches of chemical products) prior to its delivery.
Though this goes on to say:
It is also known as functional testing, black-box testing, release acceptance, QA testing, application testing, confidence testing, final testing, validation testing, or factory acceptance testing
with a "citation needed" mark.
Functional testing (which actually redirects to System Testing):
conducted on a complete, integrated system to evaluate the system's compliance with its specified requirements. System testing falls within the scope of black box testing, and as such, should require no knowledge of the inner design of the code or logic.
So from this definition they are pretty much the same thing.
In my experience acceptance test are usually a subset of the functional tests and are used in the formal sign off process by the customer while functional/system tests will be those run by the developer/QA department.
Acceptance testing is just testing carried out by the client, and includes other kinds of testing:
Functional testing: "this button doesn't work"
Non-functional testing: "this page works but is too slow"
For functional testing vs non-functional testing (their subtypes) - see my answer to this SO question.
The relationship between the two:
Acceptance test usually includes functional testing, but it may include additional tests. For example checking the labeling/documentation requirements.
Functional testing is when the product under test is placed into a test environment which can produce variety of stimulation (within the scope of the test) what the target environment typically produces or even beyond, while examining the response of the device under test.
For a physical product (not software) there are two major kind of Acceptance tests: design tests and manufacturing tests. Design tests typically use large number of product samples, which have passed manufacturing test. Different consumers may test the design different ways.
Acceptance tests are referred as verification when design is tested against product specification, and acceptance tests are referred as validation, when the product is placed in the consumer's real environment.
They are the same thing.
Acceptance testing is performed on the completed system in as identical as possible to the real production/deployement environment before the system is deployed or delivered.
You can do acceptance testing in an automated manner, or manually.
There are a lot of testing methods out there i.e. blackbox, graybox, unit, functional, regression etc.
Obviously, a project cannot take on all testing methods. So I asked this question to gain an idea of what test methods to use and why should I use them. You can answer in the following format:
Test Method - what you use it on
e.g.
Unit Testing - I use it for ...(blah, blah)
Regression Testing - I use it for ...(blah, blah)
I was asked to engage into TDD and of course I had to research testing methods. But there is a whole plethora of them and I don't know what to use (because they all sound useful).
1. Unit Testing is used by developers to ensure unit code he wrote is correct. This is usually white box testing as well as some level of black box testing.
2. Regression Testing is a functional testing used by testers to ensure that new changes in system has not broken any of existing functionality
3. Functional testing is testing conducted on a complete, integrated system to evaluate the system's compliance with its specified requirements. Functionality testing falls within the scope of black box testing, and as such, should require no knowledge of the inner design of the code or logic
.
This Test-driven development and Feature Driven Development wiki articles will be of great help for you.
For TDD you need to follow following process:
Document feature (or use case) that
you need to implement or enhance
in your application that
currently does not exists.
Write set of functional test
cases that can ensure above
feature (from step 1) works. You may need to
write multiple test cases for
above feature to test all different
possible work flows.
Write code to implement above feature (from step 1).
Test this code using test cases you
had written earlier (in step 2). The actual
testing can be manual but I would recommend to create automated tests
if possible.
If all test cases pass, you are good to
go. If not, you need to update code (go back to step 3)
so as to make the test case pass.
TDD is to ensure that functional test cases which were written before you coded should work and does not matter how code was implemented.
There is no "right" or "wrong" in testing. Testing is an art and what you should choose and how well it works out for you depends a lot from project to project and your experience.
But as a professional Test Expert my suggestion is that you have a healthy mix of automated and manual testing.
(Examples below are in PHP but you can easily find the correct examples for what ever langauge/framework you are using)
AUTOMATED TESTING
Unit Testing
Use PHPUnit to test your classes, functions and interaction between them.
http://phpunit.sourceforge.net/
Automated Functional Testing
If it's possible you should automate a lot of the functional testing. Some frame works have functional testing built into them. Otherwise you have to use a tool for it. If you are developing web sites/applications you might want to look at Selenium.
http://www.webinade.com/web-development/functional-testing-in-php-using-selenium-ide
Continuous Integration
Use CI to make sure all your automated tests run every time someone in your team makes a commit to the project.
http://martinfowler.com/articles/continuousIntegration.html
MANUAL TESTING
As much as I love automated testing it is, IMHO, not a substitute for manual testing. The main reason being that an automated can only do what it is told and only verify what it has been informed to view as pass/fail. A human can use it's intelligence to find faults and raise questions that appear while testing something else.
Exploratory Testing
ET is a very low cost and effective way to find defects in a project. It take advantage of the intelligence of a human being and a teaches the testers/developers more about the project than any other testing technique i know of. Doing an ET session aimed at every feature deployed in the test environment is not only an effective way to find problems fast, but also a good way to learn and fun!
http://www.satisfice.com/articles/et-article.pdf
This answer is (almost) identical to one that I gave to another question. Check out that question since it had some other good answers that might help you.
How can we decide which testing method can be used?
I usually do the following things:
Page consistency in case of multi-page web sties.
Testing the database connections.
Testing the functionalities that can be affected by the change I just made.
I test functions with sample input to make sure they work fine (especially those that are algorithm-like).
In some cases I implement features very simply hard-coding most of the settings then implement the settings later, testing after implementing every setting.
Most of these apply to applications, too.
Well before going to the answer i would like to clear testing concept about multiple methods.
There are six main testing types which cover all most all testing methods.
Black Box Testing
White Box Testing
Grey Box Testing
Functional Testing
Integration Testing
Usability Testing
Almost all Testing methods lies under these types, you can also use some testing method in multiple types like you can use Smoke testing in black box or white box approach on the basis of resources available to test.
So for testing a web site completely you need to use at least following testing methods on the basis of resources available to test. These are at least methods which should be used to test a web site, but there may be some more imp methods on the basic of nature of website.
Requirement Testing
Smock Testing
System Testing
Integration Testing
Regression Testing
Security Testing
Performance & Load Testing
Deployment Testing
You should at least use all of above (8) testing methods to test a web site no matter what testing type you are focusing. You can automate you test in some areas and you can do this manually it all depends upon the resources availability.
There is specifically no hard and fast rule to follow any testing type or any method. As you know "Testing Is An ART" so art don't have rules or boundaries. Its totally up to you What you use to test and how.......
Hope you got the answer of question.
Selenium is very good for testing websites.
The answer depends on the Web framework used (if any). Django for example has built-in testing functions.
For PHP (or functional web testing), SimpleTest is pretty good and well... simple. It support Unit Testing (PHP only) and Web Testing. Tests can run in the IDE (Eclipse), or in the browser (meaning on your server).
The other answers posted so far focus on unit/functional/performance/etc. testing, and they are all reasonable.
However, one the key questions you should ask is, "how effective is my testing?".
This is often answered with test coverage tools, that determine which parts of your application actually get exercised by some set of tests. The ideal test coverage tool lets you test your application by any method you can imagine (including all the standard answers above) and will then report what part and what percentage of your code was exercised. Most importantly, it will tell you what code you did not exercise. You can then inspect that code and decide if more testing is warranted, or if you don't care. If the untested code has to do with "disk full error handling" and you belive that 1TB disks are common, you might decide to ignore that. If the untested code is the input validation logic leading to SQL queries, you might decide that you must test that logic to ensure that no SQL injection attacks can occur.
What test coverage tools let you do it to make a rational decision that you have tested adequately, using data about what parts of your code has been exercised. So regardless of how you test, best practices indicates you should also do test coverage analysis.
Test coverage tools can be obtained from a variety of sources. SD provides a family of test coverage tools that handle C, C++, Java, C#, PHP and COBOL, all of which are used to support web site testing in various ways.