I have a set of base tests that are used to test multiple implementations of a interface. The way I modelelled this was by creating a base text fixture with a [Ignore] attribute.
[TestFixture]
[Ignore]
public class BaseTests
{
// Use your imagination for the actual name
public virtual ITestableThing GetConcrete()
{
return null;
}
// All of my unit tests here
}
And then I write a subclass for each interface implementation:
public class ConcreteThingTests : BaseTests
{
public override ITestableThing GetConcrete()
{
return new ConcreteThing();
}
}
This works well, as I have all of the tests for ALL implementations in one place, and the sub classes just specify the implementation.
The problem is that I have to put the [Ignore] attribute on the base class, or NUnit will try to run the tests (and fail).
Because of this, my test results are always cluttered up with a set of Ignored tests, and while it's not a big deal, I thought there might be a better pattern for this that avoids having to ignore tests.
So, am I implementing test fixture inheritance wrong?
The NUnit test runner appears to ignore the base class if it is marked abstract:
public abstract class BaseTests
{
}
You would normally set the test attributes on your concrete test classes, not the base class.
Since you seem to test the same functionality for multiple classes, you could skip the whole test hierarchy and inject the concrete classes to be tested to that test-baseclass.
To do that with NUnit you could use the TestCaseSource attribute with a class factory method as a parameter. An example of that can be found here: How to pass dynamic objects into an NUnit TestCase function?
Making up some code for your particular case, it could be like shown below:
/// <summary>
/// Earlier known as your BaseTests class
/// </summary>
[TestFixture]
public class TestOfConcreteImplementationsOfInterface
{
[TestCaseSource("CreateConcretes")]
[Test]
public void VerifyImplementations(IWhatever thing)
{
int input = 42;
int result = thing.DoSomething(input);
Assert.That(result, Is.EqualTo(input));
}
/// <summary>
/// Factory method for the concrete classes. If you want this in a seperate class, you can do that too using the
/// ctor public TestCaseSourceAttribute(Type sourceType, string sourceName);
/// </summary>
public IEnumerable<IWhatever> CreateConcretes
{
get
{
yield return new A();
yield return new B();
}
}
}
public interface IWhatever
{
int DoSomething(int x);
}
public class A : IWhatever
{
public int DoSomething(int x)
{
return x;
}
}
public class B : IWhatever
{
public int DoSomething(int x)
{
return x;
}
}
Related
Single interface: IDoSomething {...}
Two classes implement that interface:
ClassA : IDoSomething {...}
ClassB : IDoSomething {...}
One class uses any of those classes.
public class DummyClass(IDoSomething doSomething) {...}
code without Autofac:
{
....
IDoSomething myProperty;
if (type == "A")
myProperty = new DummyClass (new ClassA());
else
myProperty = new DummyClass (new ClassB());
myProperty.CallSomeMethod();
....
}
Is it possible to implement something like that using Autofac?
Thanks in advance,
What you are looking for is, as I remember, the Strategy Pattern. You may have N implementations of a single interface. As long you register them all, Autofac or any other DI framework should provide them all.
One of the options would be to create a declaration of the property with private setter or only getter inside Interface then implement that property in each of the class. In the class where you need to select the correct implementation, the constructor should have the parameter IEnumerable<ICommon>.
Autofac or any other DI frameworks should inject all possible implementation. After that, you could spin foreach and search for the desired property.
It may look something like this.
public interface ICommon{
string Identifier{get;}
void commonAction();
}
public class A: ICommon{
public string Identifier { get{return "ClassA";} }
public void commonAction()
{
Console.WriteLine("ClassA");
}
}
public class A: ICommon{
public string Identifier { get{return "ClassB";} }
public void commonAction()
{
Console.WriteLine("ClassA");
}
}
public class Action{
private IEnumerable<ICommon> _common;
public Action(IEnumerable<ICommon> common){
_common = common;
}
public void SelectorMethod(){
foreach(var classes in _common){
if(classes.Identifier == "ClassA"){
classes.commonAction();
}
}
}
}
In my application, I have a service that requires a constructor parameter not resolved by Autofac, that I instantiate using a delegate factory:
public class Service
{
public Service(string parameter /*, ... other dependencies */)
{
}
public delegate Service Factory(string parameter);
}
This works great! I really love this feature.
I also like the Controlled Lifetime relationship, so I can let my component depend on a Func<Owned<ISomething>> like this:
public class Component
{
private Func<Owned<ISomething>> _somethingFactory;
/* constructor omitted for brevity */
public void DoSomethingUseful()
{
using (var ownedSomething = _somethingFactory())
{
/* Lots of useful code here */
}
}
}
My problem is that now I want to combine the two. I can't have an instance of Func<Owned<Service>> injected, because it needs that parameter, so my current solution is to abstract the factory away into another service, say IServiceFactory:
public interface IServiceFactory
{
Service Create(string parameter);
}
...implemented as such:
public class ServiceFactory : IServiceFactory
{
private Service.Factory _internalFactory;
public ServiceFactory(Service.Factory internalFactory)
{
_internalFactory = internalFactory;
}
public Service Create(string parameter)
{
return _internalFactory(parameter);
}
}
My component then becomes this:
public class Component
{
Func<Owned<IServiceFactory>> _serviceFactoryFactory;
/* ... */
}
The need for such a field name leaves a bad taste in my mouth to the point that I suspect there must be a cleaner way to handle this case.
Is there another way?
You could change your injected factory to include the string parameter:
private Func<string, Owned<ISomething>> _somethingFactory;
Then you can pass the string to the factory when you want to create a new instance:
public void DoSomethingUseful()
{
using (var ownedSomething = _somethingFactory("my parameter"))
{
/* Lots of useful code here */
}
}
I've created a .NET Fiddle with a small working sample.
I want to run the same JUnit tests for different interface implementations. I found a nice solution with the #Parameter option:
public class InterfaceTest{
MyInterface interface;
public InterfaceTest(MyInterface interface) {
this.interface = interface;
}
#Parameters
public static Collection<Object[]> getParameters()
{
return Arrays.asList(new Object[][] {
{ new GoodInterfaceImpl() },
{ new AnotherInterfaceImpl() }
});
}
}
This test would be run twice, first with the GoodInterfaceImpl then with the AnotherInterfaceImpl class. But the problem is I need for most of the testcases a new object. A simplified example:
#Test
public void isEmptyTest(){
assertTrue(interface.isEmpty());
}
#Test
public void insertTest(){
interface.insert(new Object());
assertFalse(interface.isEmpty());
}
If the isEmptyTest is run after the insertTest it fails.
Is there an option to run automatically each testcase with a new instance of an implementation?
BTW: Implementing a clear() or reset()-method for the interface is not really an options since I would not need it in productive code.
Here is another approach with the Template Method pattern:
The interface-oriented tests go into the base class:
public abstract class MyInterfaceTest {
private MyInterface myInterface;
protected abstract MyInterface makeContractSubject();
#Before
public void setUp() {
myInterface = makeContractSubject();
}
#Test
public void isEmptyTest(){
assertTrue(myInterface.isEmpty());
}
#Test
public void insertTest(){
myInterface.insert(new Object());
assertFalse(myInterface.isEmpty());
}
}
For each concrete class, define a concrete test class:
public class GoodInterfaceImplTest extends MyInterfaceTest {
#Override
protected MyInterface makeContractSubject() {
// initialize new GoodInterfaceImpl
// insert proper stubs
return ...;
}
#Test
public void additionalImplementationSpecificStuff() {
...
}
}
A slight advantage over #Parameter is that you get the name of the concrete test class reported when a test fails, so you know right away which implementation failed.
Btw, in order for this approach to work at all, the interface must be designed in a way which allows testing by the interface methods only. This implies state-based testing -- you cannot verify mocks in the base test class. If you need to verify mocks in implementation-specific tests, these tests must go into the concrete test classes.
Create a factory interface and implementations, possibly only in your test hierarchy if you don't need such a thing in production, and make getParameters() return a list of factories.
Then you can invoke the factory in a #Before annotated method to get a new instance of your actual class under test for each test method run.
Just in case somebody reaches here(like I did), looking for testing multiple implementations of the same interface in .net you could see one of the approaches that I was using in one of the projects here
Below is what we are following in short
The same test project dll is run twice using vstest.console, by setting an environment variable. Inside the test, (either in the assembly initialize or test initialize) register the appropriate implementations into a IoC container, based on the environment variable value.
In Junit 5 you could do:
#ParameterizedTest
#MethodSource("myInterfaceProvider")
void test(MyInterface myInterface) {}
static Stream<MyInterface> myInterfaceProvider() {
return Stream.of(new ImplA(), new ImplB());
}
interface MyInterface {}
static class ImplA implements MyInterface {}
static class ImplB implements MyInterface {}
I am trying to configure an application such that types from assemblyA can be used by my console to allow for logging in an AOP style. The JournalInterceptor will just write out method calls, input and maybe output arguments to a log file or datastore of some kind.
I can register one type at a time but I would like to register all types in one go. Once I get going I may add some filtering to the registered types but I am missing something.
I am trying to use Classes.FromAssemblyContaining but am not sure how to get at an IRegistration instance for the call to WindsorContainer::Register
Any clues?
// otherAssembly.cs
namespace assemblyA
{
public class Foo1 { public virtual void What(){} }
public class Foo2 { public virtual void Where(){} }
}
// program.cs
namespace console
{
using assemblyA;
public class JournalInterceptor : IInterceptor {}
public class Program
{
public static void Main()
{
var container = new Castle.Windsor.WindsorContainer()
.Register(
Component.For<JournalInterceptor>().LifeStyle.Transient,
// works but can't be the best way
Component.For<Foo1>().LifeStyle.Transient
.Interceptors<JournalInterceptor>(),
Component.For<Foo2>().LifeStyle.Transient,
.Interceptors<JournalInterceptor>(),
// how do I do it this way
Classes.FromAssemblyContaining<Foo1>()
.Pick()
.LifestyleTransient()
.Interceptors<JournalInterceptor>()
);
Foo1 foo = container.Resolve<Foo1>();
}
}
}
Implement a Pointcut. In Castle Windsor this is done by implementing the IModelInterceptorsSelector interface.
It would go something like this:
public class JournalPointcut : IModelInterceptorsSelector
{
public bool HasInterceptors(ComponentModel model)
{
return true; // intercept everything - probably not a good idea, though
}
public InterceptorReference[] SelectInterceptors(
ComponentModel model, InterceptorReference[] interceptors)
{
return new[]
{
InterceptorReference.ForType<JournalInterceptor>()
}.Concat(interceptors).ToArray();
}
}
Then register the Interceptor and the Pointcut with the container:
this.container.Register(Component.For<JounalInterceptor>());
this.container.Kernel.ProxyFactory.AddInterceptorSelector(new JournalPointcut());
For in-depth explanation, you may want to see this recording.
If I have the following code:
[TestFixture]
public class MyBaseTest
{
protected ISessionManager _sessionManager;
[SetUp]
public void SetUp() { /* some code that initializes _sessionManager */ }
}
[TestFixture]
public class MyDerivedTest : MyBaseTest
{
IBlogRepository _repository;
[SetUp]
public void SetUp() { /* some code that initializes _repository */ }
[Test]
public void BlogRepository_TestGoesHere() { /* some tests */ }
}
...NUnit doesn't call the base SetUp routine. This is expected, and I don't have a problem with it in itself. I can get the derived SetUp to call the base SetUp first, like this:
[TestFixture]
public class MyDerivedTest : MyBaseTest
{
IBlogRepository _repository;
[SetUp]
public new void SetUp()
{
base.SetUp();
/* some code that initializes _repository */
}
This is ugly. If it was a constructor, I wouldn't have to.
I could use the "template method" pattern, and have the following:
public void MyBaseTest
{
abstract void SetUp();
[SetUp]
public void BaseSetUp()
{
/* base initialization */
SetUp(); // virtual call
}
}
I'm not particularly fond of this, either.
What do you do when their test classes need SetUp, and they're derived from another class that also needs SetUp?
You have to call the method directly.
[SetUp]
public void DerivedSetUp()
{
base.BaseSetUp();
// Do something else
}
Edit: I haven't tried it, but perhaps a partial method might work too. I'd prefer to do the above though.
Edit2: I've just tried using partial methods. It didn't work. Even if it did, I think it's still going to be easier to call the base class.
You have the base class explicitly. Given that NUnit uses the [Setup] attribute to mark up test setup, I tink this is "the right thing" to do for NUnit, because it follows the usual language rules.
Sure, NUnit could search the base classes, and call their Setup functions automagically, but I think this would be rather surprising for most people.
There is however at least one unit testing framework that uses constructors for setup: xUnit.Net. Here, the base class setup is called automatically, because this is how constructors in C# behave.
(Note, though, that xUnit.Net recommends again using test setup.)
It looks like you want the setup to be run once before any testing starts, not once before each test is run. The annotation [SetUp] makes the method run once before each test in your fixture is run. [SetUp] is not inherited.
The annotation you want to use is [TestFixtureSetUp] which is run only once, before any of the tests in a fixture are run. This is inherited in the way that you would expect. :)
See the TextFixtureSetUp docs
An approach that I use that I learned in the TDD FireStarter in Tampa was to have the setup method in the base class and then to have a virtual method in the base class called observe. This method is then called in the base class at the end of the setup method.
Then what you do is in the new class that derives from the base class you will override the observe method. The trick in this scenario is you want to execute the Setup method of the base class and the child class does not have a Setup method. The reason for this is the code that you have in the observe method are only those additional things you need for the child test class.
This approach works well for me, but one gotcha is that the test runner will want to execute the base class tests, so what I do to get around that is to move the Tests from the base class into a new class that derives from the base if I have any.
The following works in MbUnit. It may work in NUnit as well.
[TestFixture]
public abstract class Base {
[SetUp]
public virtual void SetUp() {
//Some stuff.
}
}
public class Derived : Base {
public override void SetUp() {
base.SetUp();
//Some more stuff.
}
[Test]
public virtual void Object_WhenInACertainState_WhenAMethodIsCalled_Throws() {
//Create and set state on the object.
//Call the method.
//Assert the method threw.
}
}