I was wondering what approaches others might have for testing domain services against a database? I already have a series of mock repositories that I am able to use in the domain services for testing the domain services themselves. Part of the construction of these mock repositories is that they build out sample aggregates and associated entities and validate them against the same business rules that would otherwise be used within the model. This also provides a nice and simple means to detect potential impact points within the entities themselves, in the event that their interfaces change.
The main problem that I see with live testing of my SQL-backed repositories is database consistency. For example, once a test is run the "create" aspects have already been run. Running them again would obviously cause failures, as the database is no longer pristine. I was considering create a mirrored database used just for this type of testing. It would be minimal, containing structure, programmability, constraints, etc. I would also provide a minimal set of data for certain established tests. My line of thinking is that I could have a stored procedure that I could call to reset the database to the "pristine" state with base data before the start of the test run.
While this is not as important on a developer machine after the functionality has been initially verified, I am looking more into the importance of running these tests as part of the nightly build; so that in the event of a test failure, the build could be held back as to not foul the target deployment environment (specifically in this case, it would be the environment that the testing team uses).
I do not necessarily think that the platform matters, but in case anyone has implementation specific concerns, my environment looks like the following:
Windows 7 (Development) / Windows Server 2008 R2 (Server)
Visual Studio 2008 Team Edition (C#)
Microsoft SQL Server 2008 Standard (Development/Server)
I am using Team Build to run my builds, but that is most likely not a factor in the scope of the question.
For example, once a test is run the "create" aspects have already been run. Running them again would obviously cause failures, as the database is no longer pristine.
Maybe you could make your unit tests transactional. Run your tests, roll them back, and the database is unchanged.
Spring has transactional unit test classes that make this easy to do. You just need a transaction manager.
You can use SQL Server Express (I've done it with 2005, but haven't tried with 2008) to set up "test deck" databases that are stored as files. These can be checked in to source control, then test helper classes can (a) copy them to temporary folders, (b) write-enable them, and (c) connect to them. To restore the original state, delete the temporary copy and repeat a-c.
This is a huge pain. If you can get by with transactions (as duffymo suggested) I'd go with that. The pain points with transactions are nested transactions and distributed ones - watch out for those in your code.
You can create a bunch of data factories in testing code which initially run on startup of your test run. Then use the transaction rollback method to keep it pristine.
To make it easier, subclass all your test classes and put the transaction accessor and rollback code in there. Rollback code can be set to automatically run at the completion of every test method.
if you are actually executing unit tests for your repository that are hitting a database, YOU ARE NOT DOING UNIT TESTING. It might be a helpful test but it's not a unit test. That's an integration test. If you want to do that and call it a integration test then that is perfectly fine. However, if you are following good design principles in your repositories then you do not need to test the database, EVER, in your unit tests.
Quite simply, your repository unit test is NOT to test what wide effects occur in the database based on the input to the repository; it is to confirm that the input to the repository results in a call to a collaborator with such and such a set of values.
You see, the repository, like the rest of your code, should follow the Single Reposibility Principle. Basically your respoitory has ONE and ONLY ONE reposibility and that is to mediate domain model API concerns to the underlying data access technoloy layer (usually ADO.Net but could be Entity Framework or L2S or whatever). Going with the example of ADO.Net calls, your repository shouldn't take on the responsibilty of being a factory for the data layer and instead should take a dependency on a collaborator from the ADO.Net data interfaces (specifically IDbConnection/IDbCommand/IDbParameter etc). Simply take an IDbConnection as a constructor parameter and call it a day. This means that you can write repository unit tests against the interfaces and supply mocks (or fakes or stubs or whatever you need) and confirm that the required methods, in order, with the expected inputs are made. Go check out my MS blog on this exact topic -> http://blogs.msdn.com/b/schlepticons/archive/2010/07/20/unit-testing-repositories-a-rebuttal.aspx
Hopfully this helps you from making a mistake in your test and design in the future.
BTW: If you want to unit test the database you can. Just use Visual Studio Database Tests. Its built INTO vs and has been around since VS2005. This is nothing new. But I need to caution you, they need to be completely SEPERATE unit tests.
If your code is fairly database independent, using an in-memory database such as SQLite for unit testing (not integration testing) will give you the benefits of speed and ease (your test setups initialize the db).
Related
I'm using PHP with Laravel 5.5 framework.
I recently started writing unitTests for my code and I got a few questions:
What is the best way to interact with my database?
Should I use InMemoryDB like SQLite or Mock everything with Mockery.
If I have an interaction with DB than that is still unitTesting or Integration Testing?
Thank you for the answers in advence
I work in a company where we strive for 80% code coverage, in general we test mostly End-2-End, with database and mocking external calls, we use SQLite so our testsuite can run quickly in a local environment. When the case make sense, we unit tests it, as an example an Tax service i did for different countries i unit tested, because it was very input output based.
Why we prefer End-2-End:
It's quicker if you don't have to make unit, integration and end to end testing
You test the endpoint will actually will be used
I prefer to run with a real database if you are running with Continous Integration
There is drawbacks with SQLite, mainly it does not work as other RDB where there is a lot of settings and limitations, on top of my head i had problems with foreign key enforcing etc.
So to answer your question:
It's smart to use SQLite at least locally
In Unit Testing you are only testing one class and mocking everything else, you are basically testing that the code can execute. Note this is a oversimplified version on a very complex subject.
For functional automation we use to create a framework which is reusable for automating application. Is there any way to create Performance testing framework in jmeter. So that we can use same framework for Performance testing of different applications.
Please help if any one knows and provide more information regarding it.
You can consider JMeter as a "framework" which already comes with test elements to build requests via different protocols/transports, applying assertions, generating reports, etc.
It is highly unlikely you will be able to re-use existing script for another application as JMeter acts on protocol level therefore there will be different requests for different applications.
There is a mechanism in JMeter allowing to re-use pieces of test plan as modules so you won't have to duplicate your code, check out Test Fragments and Module Controller, however it is more applicable for a single application.
The only "framework-like" approach I can think of is adding your JMeter tests into continuous integration process so you will have a build step which will execute performance tests and publish reports, basically you will be able to re-use the same test setup and reporting routine and the only thing which will change from application to application will be .jmx test script(s). See JMeter Maven Plugin and/or JMeter Ant Task for more details.
You must first ask yourself, how dynamic is my conversation that I am attempting to replicate. If you have a very stable services API where the exposed external interface is static, but the code to handle it on the back end is changing, then you have a good shot at building something which has a long life.
But, if you are like the majority of web sites in the universe then you are dealing with developers who are always changing something, adding a resource, adding of deleting form values (hidden or not), headers, etc.... In this case you should consider that your scripts are perishable, with a limited life, and you will need to rebuild them at some point.
Having noted the limited lifetime of a piece of code to test a piece of code with a limited lifetime, are there some techniques you can use to insulate yourself? Yes. Rule of thumb is the higher up the stack you go to build your test scripts the more insulated you are from changes under the covers ( assuming the layer you build to is stable ). The trade off is with more of the intelligence under the covers of your test interface, the higher the resource cost for any individual virtual user which then dictates more hosts for test execution and more skew from client side code which can distort the view of what is coming from the server. An example, run a selenium script instead of a base jmeter script. A browser is invoked, you have the benefit of all of the local javascript processing to handle the dynamic changes and your script has a longer life.
I'd like to know something, I know that to make your test easier you should use mock during unit testing to only test the component you want, without external dependencies. But at some point, you have to bite the bullet and test classes which interact with your database, files, network, etc.
My main question is: what do you do to test these classes?
I don't feel that installing a database on my CI server is a good practice, but do you have other options?
Should I create another server with other CI tools, with all externals dependencies?
Should I run integration test on my CI as often as my unit tests?
Maybe a full-time person should be in charge to test these components manually? (or in charge to create the test environment and configure the interaction between your class and your external dependency, like editing config files of your application)
I'd like to know how do you do in the real world.
I'd like to know how do you do in the
real world ?
In the real world there isn't a simple prescription about what to do, but there is one guiding truth: you want to catch mistake/bugs/test failures as soon as possible after they are introduced. Let that be your guide; everything else is technique.
A couple common techniques:
Tests running in parallel. This is my preference; I like to have two systems, each running their own instance of CruiseControl* (which I'm a committer for), one running the unit tests with fast feedback (< 5 minutes) while another system runs the integration tests constantly. I like this because it minimizes the delay between when a checkin happens and a system test might catch it. The downside that some people don't like is that you can end up with multiple test failures for the same checkin, both a unit test failure and an integration test failure. I don't find this a major downside in practice.
A life-cycle model where system/integration tests run only after unit tests have passed. There are tools like AnthillPro* that are built around this kind of model and the approach is very popular. In their model they take the artifacts that have passed the unit tests, deploy them to a separate staging server, and then run the system/integration tests there.
If you've more questions about this topic I'd recommend the Continuous Integration and Testing Conference (CITCON) and/or the CITCON mailing list.
There are lots of CI and build|process automation tools out there. These are just representatives of their class of tools.
The approach I've seen taken most often is to run unit tests immediately on checkin, and to run more lengthy integration tests at fixed intervals (possibly on a different server; that's really up to your preference). I've also seen integration tests split into "short-running" integration tests and "long-running" integration tests, which are run at different intervals (the "short-running" tests run every hour, for example, and the "long-running" tests run overnight).
The real goal of any automated testing is to get feedback to developers as quickly as is feasible. With that in mind, you should run integration tests as often as you possibly can. If there's a wide variance in the run length of your integration tests, you should run the quicker integration tests more often, and the slower integration tests less often. How often you run any set of tests in going to depend on how long it takes all the tests to run, and how disruptive the test runs will be to shorter-running tests (including unit tests).
I realize this doesn't answer your entire question, but I hope it gives you some ideas about the scheduling part.
Depending on the actual nature of the integration tests I'd recommend using an embedded database engine which is recreated at least once before any run. This enables tests of different commits to work in parallel and provides a well defined starting point for the tests.
Network services - by definition - can also be installed somewhere else.
Always be very careful though, to keep your CI machine separated from any dev or prod environments.
I do not know what kind of platform you're on, but I use Java. Where I work, we create integration tests in JUnit and inject the proper dependencies using a DI container like Spring. They are run against a real data source, both by the developers themselves (normally a small subset) and the CI server.
How often you run the integration tests depends on how long they take to run, in my opinion. Run them as often as you can. Leave the real person out of this, and let him or her run manual system tests in areas that are difficult or too expensive to automate testing for (for instance: spelling, position of different GUI components). Leave the editing of config files to a machine. Where I work, we have system variables (DEV; TEST and so on) set on the computers, and let the app choose a config file based on that.
We are setting up a Selenium test campaign on a big web application.
The first thing we've done was to build a framework which initialize SQL data in database before the test, launch the test, archive results and then clear data.
We've integrate that in a Maven 2 process, run every day by TeamCity on a dedicated database.
We've set up several Selenium tests now but It's not as used as planned.
Reasons are that tests are sometimes broken for other reasons than regressions (data may have changed, stored procedure may have been recompiled and so on).
I would like to know if there are big success in user interface testing and if so, reasons to that. Commons errors may also interest me.
Testability helps a lot. The biggest win for testability in web apps is if all of the HTML elements you need to interact with on the page have unique and consistent attributes. If the attributes you are using to identify the HTML elements (Selenium uses xpath) are not consistent/reliable from build-to-build, or session-to-session, your test scripts will fail. Also, these attributes must be unique, so that the automation tool (in this case Selenium) can reliably find the object on the web page.
If you want reliable unit tests, you need to have the same input. Starting state of the database is the input. So, you need to have the same starting database each time. Of course, if you wish to do testing with different input, you need to create another unit test (as results will obviously not be the same).
When I do stuff like this, I always use the same database as a starting point. Of course, some of the tests might fail without modifying the database is correct way, so some other subsequent tests might fail as well even though they wouldn't otherwise. If your unit-test tool allows, you should define dependencies between tests to make sure that those tests will not be run at all when the 'parent' one fails.
I use http-unit which has the added benefit of working before any styling has been added to the page.
http://httpunit.sourceforge.net/
You can attach the tests to run in the integration test phase for maven2.
From the site
Written in Java, HttpUnit emulates the
relevant portions of browser behavior,
including form submission, JavaScript,
basic http authentication, cookies and
automatic page redirection, and allows
Java test code to examine returned
pages either as text, an XML DOM, or
containers of forms, tables, and
links.
When you are doing integration tests with either just your data access layer or the majority of the application stack. What is the best way prevent multiple tests from clashing with each other if they are run on the same database?
Transactions.
What the ruby on rails unit test framework does is this:
Load all fixture data.
For each test:
BEGIN TRANSACTION
# Yield control to user code
ROLLBACK TRANSACTION
End for each
This means that
Any changes your test makes to the database won't affect other threads while it's in-progress
The next test's data isn't polluted by prior tests
This is about a zillion times faster than manually reloading data for each test.
I for one think this is pretty cool
For simple database applications I find using SQLite invaluable. It allows you to have a unique and standalone database for each test.
However it does only work if you're using simple generic SQL functionality or can easily hide the slight differences between SQLite and your production database system behind a class, but I've always found that to be fairly easy in the SQL applications I've developed.
Just to add to Free Wildebeest's answer I have also used HSQLDB to do a similar type testing where each test gets a clean instance of the DB.
I wanted to accept both Free Wildebeest's and Orion Edwards' answers but it would not let me. The reason I wanted to do this is that I'd come to the conclusion that these were the two main ways to do it, but which one to chose depends on the individual case (mostly the size of the database).
Also run the tests at different times, so that they do not impact the performance or validity of each other.
While not as clever as the Rails unit test framework in one of the other answers here, creating distinct data per test or group of tests is another way of doing it. The level of tediousness with this solution depends on the number of test cases you have and how dependant they are on one another. The tediousness will hold true if you have one database per test or group of dependant tests.
When running the test suite, you load the data at the start, run the test suite, unload/compare results making sure the actual result meets the expected result. If not, do the cycle again. Load, run suite, unload/compare.