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Unit test of Dataprovider in .Net

I have runned into to the issue regarding unit test of dataprovider's. What are the best way to implement that.
One solution would be to insert something into the database and read it to make sure that it's as expected. And then removing it again. But this requires more coding.
The other solution is to have an extra database, which i could test against. This also requires alot of work to implement it.
What are the correct way to implement it?

As others have pointed out, what you are describing is called integration testing. Integration testing is something you should definitely do but it's good to understand the differences.
A unit test tests an individual piece of code without any dependencies. Dependencies are things like a database, file system or a web service but also other internal classes that are complex and require their own unit tests. Unit tests are made to run very fast. Especially when performing test driven development (TDD) you want your unit tests to execute in the order of milliseconds.
Integration tests are used to test how different components work together. If you have made sure through unit tests that your business logic is correct, your integration tests only have to make sure that all connections between different elements are in place. Integration tests can take a long time but you have fewer of them than unit tests.
I wrote a blog post on this some time ago that explains the differences and shows you ways to remove external dependencies while unit testing: Unit Testing, hell or heaven?.
Now regarding, your question. When running integration tests against a database you have a couple of options:
Use delta testing. This means that at the beginning of your test you record the current state of your database. For example, you store that are now 3 people in the people table. Then in your test you add one person and verify that there are now 4 people. in the database. This can be used quite effectively in simple scenarios. However, when your project grows more complex this is probably not the way to go.
Use a transaction around your unit tests. This is an easy way to make sure that your tests don't leave any data behind. Just start a new transaction (using the TransactionScope class in the .NET Framework) at the beginning of the test. As long as you don't complete the transaction, all changes will be rolled back automatically.
Use a new database for each test. Using localdb support in Visual Studio 2012 and higher, this can be done relatively fast.
I've chosen for the transaction scope a couple of times before and it worked quite well. One thing that's very important when writing integration tests like this is to make sure that your tests don't depend upon eachother. They need to run in whatever order the test runner decides on.
You should also make sure to avoid any 'magic numbers'. For example, maybe you know that your database contains 3 people so in your test you add one person and then assert that there are four in the database. For readers of your tests (which will be you in a couple of days, weeks or months) this is very hard to understand. Make sure that your tests are self explaining and that you don't depend on external state that's not obvious from the test.

You cannot unit test external dependencies like database connections. There is a good post here about why this is the case. In short: external dependencies should be tested, but that's integration tests, not unit tests.

Normally you do write intergration test when you call your database from code. If you want to write unittest, you should have a look at mocking frameworks.

Best Practice - What to do when creating Unit Test with huge amount of entities

I am creating an unit test, but there are many entities. So do I have to insert all entities at database manually or is there any better solution?

Are you looking for something like Moq? You use it to create a Mock objects and Queryable lists of objects so that you don't need to put fake data into your database to test.

Have a look at this link on how to get going on writing unit tests. The one thing I think that may help you in regard to your question:
Mock out all external services and state
Otherwise, behaviour in those external services overlaps multiple tests, and state data means that different unit tests can influence each other’s outcome.
You’ve definitely taken a wrong turn if you have to run your tests in a specific order, or if they only work when your database or network connection is active.
(By the way, sometimes your architecture might mean your code touches static variables during unit tests. Avoid this if you can, but if you can’t, at least make sure each test resets the relevant statics to a known state before it runs.)

Unit testing database code [duplicate]

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Closed 11 years ago.
Possible Duplicate:
Unit testing on code that uses the Database
I am just starting with unit testing and wondering how to unit test methods that are making actual changes to my database. Would the best way be to put them into transactions and then rollback, or are there better approaches to this?

If you want proper test coverage, you need two types of tests:
Unit-tests which mock all your actual data access. These tests will not acually write to the database, but test the behaviour of the class that does (which methods it calls on other dependencies, etc.)
System tests (or integration tests) which check that your database can be accessed and modified. I would considered two types of tests here: simple plain CRUD tests (create / read / update / delete) for each one of your model objects, and more complex system tests for your actual methods, and everything you deem interesting or valuable to test. Good practices here are to have each test starting from an empty (or "ready for the test") database, do its stuff, then check state of the database. Transactions / rollbacks are one good way to achieve this.

For unit testing you need to mock or stub the data access code, mostly you have repository interface and you can stub it by creating a concrete repository which stores data in memory, or you could mock it using dynamic mocking framework ..
For system or integration testing, you need to re-create the entire database before each test method in order to maintain a stable state before each test.

As per some of the previous answers if you want to test your data access code then you might want to think about mocks and a system/integration test strategy.
But, if you want to unit test your SQL objects (eg sprocs, views, constraints in tables etc) - then there are a number of database unit testing frameworks out there that might be of interest (including one that I have written).
Some implement tests within SQL, others within your code and use mbUnit/NUnit etc.
I have written a number of articles with examples on how I approach this - see http://dbtestunit.wordpress.com/
Other resources that might be of use:
http://www.simple-talk.com/sql/t-sql-programming/close-those-loopholes---testing-stored-procedures--/
http://tsqlt.org/articles/

The general approach is to have a way to mock you database actions. So that your unit tests are not reliant on the database being available or in a certain state. That said it also implies design that facilitates the isolation required to mock away your data layer. Unit test and how to do it well is a huge topic. Take a look on the googley for Mock Frameworks, and Dependency injection for a start.

If you are not developing an O/R mapper, there's no need to test database code. You don't want to test ADO.NET methods, right? Instead you want to verify that the ADO.NET methods are called with the right values.
Search Google for repository pattern. You will create an implementation of IRepository interface with CRUD methods and test/mock this.

If you want to test against a real database, this would be more of an integration then a unit test. Wrapping your tests in transaction could be an idea to keep your database in a consistent state.
We've done this in a base class and used the TestInitialize and TestCleanup functions to make sure this always happens.
But testing against a real database will certainly bring you into performance problems. So make sure from the beginning that you can swap your database access code with something that runs in memory. I don't now which database access code your targeting but design patterns like UnitOfWork and Repository can help you to isolate your database code and replace it with an in memory solution.

Integration Testing: Am I doing it right?

Here's an integration test I wrote for a class that interacts with a database:
[Test]
public void SaveUser()
{
// Arrange
var user = new User();
// Set a bunch of properties of the above User object
// Act
var usersCountPreSave = repository.SearchSubscribersByUsername(user.Username).Count();
repository.Save(user);
var usersCountPostSave = repository.SearchSubscribersByUsername(user.Username).Count();
// Assert
Assert.AreEqual(userCountPreSave + 1, userCountPostSave);
}
It seems to me that I can't test the Save function without involving the SearchSubscriberByUsername function to find out if the user was successfully saved. I realize that integration tests aren't meant to be unit tests which are supposed to test one unit of code at a time. But ideally, it would be nice if I could test one function in my repository class per test but I don't know how I can accomplish that.
Is it fine how I've written the code so far or is there a better way?

You have a problem with your test. When you're testing that data is saved into the database, you should be testing that it's in the database, not that the repository says that it's in the database.
If you're testing the functionality of repository, then you can't verify that functionality by asking if it has done it correctly. It's the equivalent of saying to someone 'Did you do this correctly?' They are going to say yes.
Imagine that repository never commits. Your test will pass fine, but the data won't be in the database.
So, what I would do is to to open a connection (pure SQL) to the database and check that the data has been saved correctly. You only need to a select count(*) before and after to ensure that the user has been saved. If you do this, you can avoid using the SearchSubscribersByUsername as well.
If you're testing the functionality of repository, you can't trust repository, by definition.

To unit test something like a "Save" function, you will definitely need some trustworthy channel to check the result of the operation. If you trust SearchSubscribersByUsername (because you have already made some unit tests for that function on its own), you can use it here.
If you don't trust SearchSubscribersByUsername and you think your unit test could also break because there is an error in that function (and not in Save), you should think about a different channel (perhaps you have a possibility to make a bypassing SQL access to your DB to check the Save result, which may be simpler than the implementation of SearchSubscribersByUsername)? However, do not reimplement SearchSubscribersByUsername again, that would be getting pointless. Either way, you will need at least some other function you can trust.

Unless the method you are testing returns definitive information about what you have done I don't see any way to avoid calling other methods. I think you are correct in your assumption that Integration testing needs a different way of thinking from Unit testing.
I would still build tests that focus on individual methods. So in testing Save() I may well use the capabilities of Search(), but my focus is on the edge cases of Save(). I build tests that deal with duplicate insertions or invalid input data. Then later I build a whole raft of Search() tests that deal with the edge cases of Search().
Now one possible way of thinking is that Save and Search have some commonality, a bug in Search might mask a bug in Save. Imagine, for example, if you had a caching layer down there. So possibly an alternative approach is to use some other verification mechanism. For example a direct JDBC call to the database, or alteratively introducing mocking layers at some point in your infrastructure. When building complex Integrated Systems this kind of "Back Door" verification may be essential.

Personally, I've written countless tests very similar to this and think its fine. The alternative is to stub out the database so that searchSubscribers never actually does anything but thats great deal of work for what I'd say is little gain.

Mocking webservice calls...sometimes

I am trying to write acceptance testing for an existing app.
I've run into a problem though when calling a web service that tells us if a person is, in short, in the office or not, what hours, and who the backup is.
In most of the tests, actually calling the web service is fine... yes, ideally it shouldn't, but creating inputs and outputs for the many many times this service is called is a HUGE task.
What I'd like to do is have the Mock generate a default result regardless of the input, but it will need to be generated by code based on the parameters as there is temporal data in the call and result.
And, if I choose, to be able to setup a different result on a few select inputs to the method on a test by test scenario.
Basically, by default, people are in the office. Unless I setup the mock for them not to be.
Can I do that with Moq? And how?
I'm pretty new to writing tests and mocking so if you require more clarification, please ask.

You may be able to do that with Moq or another dynamic Mock, but it doesn't sound like it would be a good idea.
The way you describe your needs it sounds like you want the web service to contain a non-trivial amount of logic - perhaps not as complex logic as the final production web service, but a set of heuristic rules at least. That sounds to me a lot like a Fake instead of a Mock.
In short, a Fake is a lightweight implementation of the dependency.
A Mock, on the other hand, provides more or less pre-canned, static answers to input while verifying whether the input was expected or not. That doesn't sound at all like what you describe.
In short, the best way to achieve what you describe is to write a lightweight version of the web service that act as you describe. If you need to generate some bogus test data, you can consider using AutoFixture.

There is a misunderstood difference bethween mocks and stubs [Martin Forler: Mock Aren't Stubs (http://martinfowler.com/articles/mocksArentStubs.html].
Basically the mock objects serves as the objects with the mechanism that allows you to verify that the method tested during some testing scenario (mostly the Unit tests) is using the object correctly (ie. verify that the tested method called the mock object's methods in correct order, set the parameters and accessed the property three times ...). The mock serves for purpose of testing the method within the unit test whether it is using another objects that are beyond it's boundaries correctly.
On the other hand the stubs are simulating some behavior (this is what I think you seek).

You could try the web based mocking utility from sourceForge. The application allows to configure selected response based on a particula input tag value.
http://sourceforge.net/projects/easymocker
Web Service Mocker is an easy to use, completely web based SOAP web service mocking utility. This utility is found very useful in a SOA development environment during unit test, component integration test and non-functional requirement testing.