How would you test the following code?
public IList<T> Find(DetachedCriteria criteria)
{
return criteria.GetExecutableCriteria(session).List<T>();
}
I would like to mock NH implementation (like setting mocks for ISession, ISessionFactory etc.) but I am having trouble with this one.
You shouldn't really test this as that would be testing NHibernate. As a matter of fact, you can see very similar unit tests in NH source code itself.
If you wanted to test some other code that uses this code, here's how you'd stub it:
Db.Stub(x => x.Find(Arg<DetachedCriteria>.Is.Anything))).Return(new List<Blah>{new Blah()});
In my experience, if you want to test your queries (e.g. the ones that build the DetachedCriteria) you are much better of with an in-memory DB like SQLite, or better yet, a real SQL Server instance (or SQL Server CE for in-memory).
Related
I'm using AutoMapper for mapping Entity Framework entities to business entities. Business logic classes take IMappingEngine as dependency through their constructors. Then it is used in methods like this:
public int DoSomething()
{
var users = _dbContext.Users.ProjectTo<UserBLL>(null, _mappingEngine);
// ...
// some users' processing and business logic that should be tested
// ...
return result;
}
Everything works perfect. The problem is unit tests. I figured from ProjectTo implementation that I need to stub IMappingEngine.CreateMapExpression method. But it seems overcomplicated. Is there any easier solution? Of course, it's possible to just use AutoMapper's implementation by configuring mapping in test setup method, and then passing Mapper.Engine to SUT, but it smells like integration test, not unit.
ProjectTo is just a way of generating a Select LINQ projection. You wouldn't stub out a call to Select, so you wouldn't stub out AutoMapper.
Just use AutoMapper directly in your unit tests. I don't see it any different than using other core framework assemblies or something like JSON.Net.
A separate question is the EF dependency. If you want this test to be a unit test, you'd need to mock out DbContext. But that route has extremely dubious value, a mocked out DbContext has much different runtime behavior than the real one, so much so I wouldn't trust it.
I don't know whether to use unit or integration tests for what I am wanting to test in my Grails 2.2.3 application. I want to run some tests against like this:
#TestFor(Student)
#Mock(Student)
class StudentTests {
void testFoundStudent() {
def s = Student.findById(myId)
assert s != null
assert s.firstName = 'Grant'
assert s.lastName = 'McConnaughey'
}
}
This is going to require the use of our test database, so would that make it an integration test? When I run this code as a unit test it fails at assert s != null. Which means it isn't using our database, because it SHOULD find a student with that ID.
In Grails unit test you can test domain class interactions using Gorm and behind the scene Grails will use in-memory database(an implementation of a ConcurrentHashMap) to mimic this behavior here. So yes you get null because that student does not exist in in-memory database and you need to insert that data first.
Student.findOrSaveWhere (firstName: 'Grant',lastName : 'McConnaughey')
In your example, if the intention is to test the existence of that data you need to use integration test and connect it to your database using datasource.groovy , which is really not a good idea unless you have a good reason to test your data.
If you are trying to test def s = Student.findById(myId) again that is not adding any value as that is Grails dynamic finder and you probably need to trust the framework you are using.
However, in general
Unit tests are typically run without the presence of physical
resources that involve I/O such databases, socket connections or
files link
I hope this helps
I have a unit test project which uses Ninject to mock the database repositories. I would like to use these same tests as integration tests and use Ninject to bind my real database repositories back into their respective implementations so as to test/stress the application into the DB.
Is there a way to do this with Visual Studio 2012 or is there another test framework, other than MSTest, which allows for this type of configuration?
I would really hate to rewrite/copy these unit tests into an integration test project but I suspect I could copy the files in as links and have a single test file compiled into two projects (Unit and Integration).
Thanks
Todd
Your requirements sound really odd to me. The difference between a unit test and an integration test is much bigger than just connecting to a database or not. An integration test either has a much bigger scope, or tests if components communicate correctly. When you write a unit test, the scope of such a unit is normally small (one class/component with all dependencies mocked out), which means there is no need for using a DI container.
Let me put it differently. When the tests are exactly the same, why are you interested to do the same test with and without the database. Just leave the database in and just test that. Besides these tests, you can add 'real' unit tests, that have a much smaller scope.
With Nunit you can do this with TestCase,
say you need to use the unit and unit/integration test using CustomerRepository and OrderRepository,
[TestFixture]
public class TestCustomerRepository
{
IKernel _unit;
Ikernel _integration;
[SetUp]
public void Setup()
{
//setup both kernels
}
[TestCase("Unit")]
[TestCase("Integration")]
public void DoTest(String type)
{
var custRepo = GetRepo<ICustomerRepository>(type);
var orderRepo = GetRepo<IOrderRepository>(type);
//do the test here
}
protected T GetRepo<T>(String type)
{
if (type.Equals("Unit"))
{
return _unit.Get<T>();
}
return _integration.Get<T>();
}
}
This is the basic idea.
This is a tough one because not too many people use Pex & Moles or so I think (even though Pex is a really great product - much better than any other unit testing tool)
I have a Data project that has a very simple model with just one entity (DBItem). I've also written a DBRepository within this project, that manipulates this EF model. Repository has a method called GetItems() that returns a list of business layer items (BLItem) and looks similar to this (simplified example):
public IList<BLItem> GetItems()
{
using (var ctx = new EFContext("name=MyWebConfigConnectionName"))
{
DateTime limit = DateTime.Today.AddDays(-10);
IList<DBItem> result = ctx.Items.Where(i => i.Changed > limit).ToList();
return result.ConvertAll(i => i.ToBusinessObject());
}
}
So now I'd like to create some unit tests for this particular method. I'm using Pex & Moles. I created my moles and stubs for my EF object context.
I would like to write parametrised unit test (I know I've first written my production code, but I had to, since I'm testing Pex & Moles) that tests that this method returns valid list of items.
This is my test class:
[PexClass]
public class RepoTest
{
[PexMethod]
public void GetItemsTest(ObjectSet<DBItem> items)
{
MEFContext.ConstructorString = (#this, name) => {
var mole = new SEFContext();
};
DBRepository repo = new DBRepository();
IList<BLItem> result = repo.GetItems();
IList<DBItem> manual = items.Where(i => i.Changed > DateTime.Today.AddDays(-10));
if (result.Count != manual.Count)
{
throw new Exception();
}
}
}
Then I run Pex Explorations for this particular parametrised unit test, but I get an error path bounds exceeded. Pex starts this test by providing null to this test method (so items = null). This is the code, that Pex is running:
[Test]
[PexGeneratedBy(typeof(RepoTest))]
[Ignore("the test state was: path bounds exceeded")]
public void DBRepository_GetTasks22301()
{
this.GetItemsTest((ObjectSet<DBItem>)null);
}
This was additional comment provided by Pex:
The test case ran too long for these inputs, and Pex stopped the analysis. Please notice: The method Oblivious.Data.Test.Repositories.TaskRepositoryTest.b__0 was called 50 times; please check that the code is not stuck in an infinite loop or recursion. Otherwise, click on 'Set MaxStack=200', and run Pex again.
Update attribute [PexMethod(MaxStack = 200)]
Question
Am I doing this the correct way or not? Should I use EFContext stub instead? Do I have to add additional attributes to test method so Moles host will be running (I'm not sure it does now). I'm running just Pex & Moles. No VS test or nUnit or anything else.
I guess I should probably set some limit to Pex how many items should it provide for this particular test method.
Moles is not designed to test the parts of your application that have external dependencies (e.g. file access, network access, database access, etc). Instead, Moles allows you to mock these parts of your app so that way you can do true unit testing on the parts that don't have external dependencies.
So I think you should just mock your EF objects and queries, e.g., by creating in-memory lists and having query methods return fake data from those lists based on whatever criteria is relevant.
I am just getting to grips with pex also ... my issues surrounded me wanting to use it with moq ;)
anyway ...
I have some methods similar to your that have the same problem. When i increased the max they went away. Presumably pex was satisfied that it had sufficiently explored the branches. I have methods where i have had to increase the timeout on the code contract validation also.
One thing that you should probably be doign though is passing in all the dependant objects as parameters ... ie dont instantiate the repo in the method but pass it in.
A general problem you have is that you are instantiating big objects in your method. I do the same in my DAL classes, but then i am not tryign to unit test them in isolation. I build up datasets and use this to test my data access code against.
I use pex on my business logic and objects.
If i were to try and test my DAL code id have to use IOC to pass the datacontext into the methods - which would then make testing possible as you can mock the data context.
You should use Entity Framework Repository Pattern: http://www.codeproject.com/KB/database/ImplRepositoryPatternEF.aspx
A few weeks ago I jumped on the MEF (ComponentModel) bandwagon, and am now using it for a lot of my plugins and also shared libraries. Overall, it's been great aside from the frequent mistakes on my part, which result in frustrating debugging sessions.
Anyhow, my app has been running great, but my MEF-related code changes have caused my automated builds to fail. Most of my unit tests were failing simply because the modules I was testing were dependent upon other modules that needed to be loaded by MEF. I worked around these situations by bypassing MEF and directly instantiating those objects.
In other words, via MEF I would have something like
[Import]
public ICandyInterface ci { get; set; }
and
[Export(typeof(ICandyInterface))]
public class MyCandy : ICandyInterface
{
[ImportingConstructor]
public MyCandy( [Import("name_param")] string name) {}
...
}
But in my unit tests, I would just use
CandyInterface MyCandy = new CandyInterface( "Godiva");
In addition, the CandyInterface requires a connection to a database, which I have worked around by just adding a test database to my unit test folder, and I have NUnit use that for all of the tests.
Ok, so here are my questions regarding this situation:
Is this a Bad Way to do things?
Would you recommend composing parts in [SetUp]
I haven't yet learned how to use mocks in unit testing -- is this a good example of a case where I might want to mock the underlying database connection (somehow) to just return dummy data and not really require a database?
If you've encountered something like this before, can you offer your experience and the way you solved your problem? (or should this go into the community wiki?)
It sounds like you are on the right track. A unit test should test a unit, and that's what you do when you directly create instances. If you let MEF compose instances for you, they would tend towards integration tests. Not that there's anything wrong with integration tests, but unit tests tend to be more maintainable because you test each unit in isolation.
You don't need a container to wire up instances in unit tests.
I generally recommend against composing Fixtures in SetUp, as it leads to the General Fixture anti-pattern.
It is best practice to replace dependencies with Test Doubles. Dynamic mocks is one of the more versatile ways of doing this, so definitely something you should learn.
I agree that creating the DOCs manually is much better than using MEF composition container to satisfy imports, but regarding the note 'compositing fixtures in setup leads to the general fixture anti pattern' - I want to mention that that's not always the case.
If you’re using the static container and satisfy imports via CompositionInitializer.SatisfyImports you will have to face the general fixture anti pattern as CompositionInitializer.Initialize cannot be called more than once. However, you can always create CompositionContainer, add catalogs, and call SatisyImportOnce on the container itself. In that case you can use a new CompositionContainer in every test and get away with facing the shared/general fixture anti pattern
I blogged on how to do unit tests (not nunit but works just the same) with MEF.
The trick was to use a MockExportProvider and i created a test base for all my tests to inherit from.
This is my main AutoWire function that works for integration and unit tests:
protected void AutoWire(MockExportProvider mocksProvider, params Assembly[] assemblies){
CompositionContainer container = null;
var assCatalogs = new List<AssemblyCatalog>();
foreach(var a in assemblies)
{
assCatalogs.Add(new AssemblyCatalog(a));
}
if (mocksProvider != null)
{
var providers = new List<ExportProvider>();
providers.Add(mocksProvider); //need to use the mocks provider before the assembly ones
foreach (var ac in assCatalogs)
{
var assemblyProvider = new CatalogExportProvider(ac);
providers.Add(assemblyProvider);
}
container = new CompositionContainer(providers.ToArray());
foreach (var p in providers) //must set the source provider for CatalogExportProvider back to the container (kinda stupid but apparently no way around this)
{
if (p is CatalogExportProvider)
{
((CatalogExportProvider)p).SourceProvider = container;
}
}
}
else
{
container = new CompositionContainer(new AggregateCatalog(assCatalogs));
}
container.ComposeParts(this);
}
More info on my post: https://yoavniran.wordpress.com/2012/10/18/unit-testing-wcf-and-mef/