Mocking an object with Moq, using Ninject when doing UnitTesting - unit-testing

I'm having trouble using Moq in a UnitTesting project with Ninject.
First a few lines about my solution. It contains several projects (BussinesLogic, DAL, Infrastructure...). My goal is to UnitTest the logic i'm using in BussinessLogic project.
The solution is basicly for a windows service, but i've put in the logic so it can be run standalone. I'm using Ninject and i specify weather i want to use the ProductionModule or the TestingModule (windows service uses ProductionModule, console app uses TestingModule)
I'm using a factory pattern to get ninject kernel whenever i need it inside my application.
My TestingModule inherits from NinjectModule where i override the Load() method and there i do the binding. For instance:
Bind<IStorageManager>().To<StubStorageManager>();
I have the StubStorageManager but it's empty. It contains just the declaration of methods from IStorageManager.
The thing i would like to do is (in laymans terms):
Create a unitTest where i would create a new kernel specifying the TestingModule as it's parameter. Then i would like to create a mock object (let's say a mock of IStorageManager) storageManagerMock. Some method in IStorageManager returns a messageObject so i would probably need to mock that too, couse the bussiness logic is doing something based on that messageObject. So i would like to somehow set properties to that message object and then call some businessLogic method on it, so i can see if the logic works correctly.
I hope i didn't complicate it too much.
Please bear with me, i'm completely new to mocking and dependency injection, but am willing to learn.

I doubt you really want to be using Ninject in your tests. The whole point of using ninject is that you can decouple everything. You also want to try and keep everything decoupled from the dependency container itself if possible. Pass it in if you have to, or pass in factories that create the required object and have the container pass in the factory.
I suspect you probably want to do something like this:
public void ATest(){
//create a mock StorageManager
var managerMock = new Mock<IStorageManager>();
//create a mock MessageObject to be used by business logic
var messageObjectMock = new Mock<MessageObject>();
//have the storage manager return the mock message when required
managerMock.Setup(x => x.GetMessageObject()).Returns(messageObjectMock.Object);
//set up message expectations
messageObjectMock.Setup(x => x.ThisValueExpected).Returns(10);
messageObjectMock.Setup(x => x.ThisFunctionShouldBeCalled()).Verifiable("Function not called.");
//thing to test
BusinessLogicObject blo = new BusinessLogicObject(managerMock.Object);
blo.DoTheThingImTesting();
//make sure the business logic called the expected function, or do whatever check you need...
messageObjectMock.Verify();
}

Related

How to unit test Service Fabric Actor with State

I've started writing unit tests for new actor with state. The state is initialised in the OnActivateAsync method which is called by Service Fabric when the Actor is activated.
When unit testing, I'm creating the Actor myself and as the method is protected I don't have access from my unit test to call this method myself.
I'm wondering on the usual approach for this kind of testing. I could mock the Actor and mock the state, but for the code I want to test call the original. Am wondering if there is another approach I've not come across.
Another approach would be to move the State initialisation to somewhere else like a public method or in the constructor but the template for an Actor has the code there so it may be a best practice.
Use the latest version of ServiceFabric.Mocks NuGet package. It contains special extension to invoke OnActivateAsync protected method and the whole tool set for ServiceFabric unit testing.
var svc = MockActorServiceFactory.CreateActorServiceForActor<MyActor>();
var actor = svc.Activate(new ActorId(Guid.NewGuid()));
actor.InvokeOnActivateAsync().Wait();
I like to use the InternalsVisibleTo attribute and an internal method on the actor, which calls the OnActivateAsync method.
In the target Actor project, AssemblyInfo.cs add a line like this:
[assembly: InternalsVisibleTo("MyActor.Test")]
Where "MyActor.Test" is the name of the test project you want to grant access to your internal members.
In the target Actor class add a method something like this:
internal Task InvokeOnActivateAsync()
{
return OnActivateAsync();
}
This way you can invoke the OnActivateAsync method from your test project something like this:
var actor = CreateNewActor(id);
actor.InvokeOnActivateAsync()
I appreciate this is not ideal, but you can use reflection to call the OnActivateAsync() method.
For example,
var method = typeof(ActorBase).GetMethod("OnActivateAsync", BindingFlags.Instance | BindingFlags.NonPublic);
await (Task)method.Invoke(actor, null);
This way you'll be testing the actual method you want to test and also won't be exposing methods you don't really want to expose.
You may find it useful to group the creation of the actor and the manual call to OnActivateAsync() in a single method so that it's used across your test suite and it mimics the original Service Fabric behaviour.

Altering fake repository for unit testing when using dependency injection

In my program I have a situation that I can simplify to the following:
An IRepository of which I create a MemoryRepository and a SqlRepository implementation
A Mapper that gets the IRepository constructor injected.
A Mapper.Map() that contains business logic I want to test
I created a test where the Mapper receives the MemoryRepository.
By explicitly setting a property on the memory repository that will be used in the business logic I can now test this logic.
If I use injection however, I wouldn't have access to this repository anymore.
A bit of code tells you more then a 1000 normal words, here is the pastebin link.
How would you go about this?
If I understand your question correctly basically you are concerned that your repository was created AND injected when the test class was instantiated and so in your test method you cannot modify the state of your repository since it is already inside your mapper and, of course, your mapper should not expose the internals of the repository.
If that is the case then I don't think you have to worry, just modify the state of the myMemoryCategoryRepository and execute the mapper's method. Your mapper should behave accordingly because what you injected is a reference to the repository so the object inside the mapper is the same one as the one you would be modifying.
Dim myMemoryCategoryRepository As MemoryCategoryRepository = MemoryKernel.Instance.Get(Of MemoryCategoryRepository)()
Dim myCategoryMapper As CategoryMapper = New CategoryMapper(myMemoryCategoryRepository)
<TestMethod()> _
Public Sub GetCategoryStartDate_CategoryStartDateAndContractStartDate_ContractStartDateIsOldestDate()
myMemoryCategoryRepository.AnyFlag = True
myCategoryMapper.Execute()
Assert.AreEqual(expectedValue, myCategoryMapper.Value)
End Sub
Not entirely sure what you're asking here, are you testing the mapper or the repository? If you're testing the mapper, then fake the repository. You've already got the seams in place, either use a framework or create a fake repository manually in your tests that makes whatever happy noises you want for the sake of testing Mapper and create the mapper by passing in your fake into the constructor.
So by your own simplification,
Create a fake Repository inheriting from IRepository
Inject the fake into your Mapper that you are going to test
Test Mapper.Map()
If you need to verify some information on the Repository, use a Mock rather than a Stub.
Difference Between Mocks and Stubs

fake directories for .net unit testing

I'm trying to create a unit test for a code similar to this:
foreach (string domainName in Directory.GetDirectories(server.Path))
{
HandleDomainDirectory(session, server, domainName);
}
The problem is that I'm using the System.IO.Directory class in my code.
How can I create a testing method that won't be dependent on any folder I have on my hard disk.
In other words, How can I fake the response of "Directory.GetDirectories(server.Path)"?
(Please note, I do control the "server" object in my class, therefore i can give any path i want)
Thanks.
Rather than calling Directory.GetDirectories(server.Path) directly, you could create an interface like IDirectoryResolver with a single method that takes a path string and returns the list of directories. The class containing your code above would then need a property or field of type IDirectoryResolver, which can be injected through the constructor or a setter.
For your production code, you would then create a new class that implements the IDirectoryResolver interface. This class could use the Directory.GetDirectories method in its implementation of the interface method.
For unit testing, you could create a MockDirectoryResolver class which implements IDirectoryResolver (or use a mocking library to create a mock instance for the interface). The mock implementation can do whatever you need it to do.
You would inject a wrapper class.
public class DirectoryFetcher
{
public virtual List<string> GetDirectoriesIn(string directory)
{
return Directory.GetDirectories(directory);
}
}
And then inject that:
foreach(string directory in _directoryFetcher.GetDirectoriesIn(server.Path))
{
// Whatever
}
You can then Mock that guy at the injection point (this example uses Moq, and constructor injection):
Mock<DirectoryFetcher> mockFetcher = new Mock<DirectoryFetcher>();
mockFetcher.Setup(x => x.GetDirectoriesIn("SomeDirectory")).Returns(new List<string>
{
"SampleDirectory1",
"SampleDirectory2"
});
MyObjectToTest testObj = new MyObjectToTest(mockFetcher.Object);
// Do Test
When communicating with the outside world, such as file system, databases, web services etc. , you should always consider using wrapper classes like the others before me suggested. Testability is one major argument, but an even bigger one is: The out side world changes, and you have no control over it. Folders move, user rights changes, new disk drives appears and old ones are removed. You only want to care about stuff like that in one place. Hence, the wrapper -- let's call it DirectoryResolver like Andy White suggested ealier.
So, wrap your file system calls, extract an interface, and inject that interface where you need to communicate with the file system.
The best solution I've found was to use Moles. The code is very specific, and must do very specific thing. Wrapping it with wrapper class will be redundant. The only reason I needed wrapper class is in order to write tests. Moles allows me to write the tests without any wrapper class :)

How to unit test file manager class?

I wrote a simple class to manage business objects.
class Manager
{
string[] GetNames();
BObject GetObject(string name);
void Saveobject(BObject obj);
}
It serializes /deserializes the objects as files on a local disk. I wrote Unit tests for the class and run them. That was fine so far. The problem happens when my test were run on build server because of file access permission I was not allowed to write files on the server. It's obvious I cannot test that way.
I think how to unit test this. One approach I can see is to extract an interface and creat a mock object for testing. But I want to test the class itself. How can I do it?
The class presumably calls file system operations File.OpenRead(), File.OpenWrite() etc. (I assume that this is C# due to the camel casing.) Then, you could create an interface for those operations, e.g.:
public interface IFileSystem {
StreamReader OpenRead(string fileName);
StreamWriter OpenWrite(string fileName);
}
and make the constructor of Manager take an instance of IFileSystem. Then, write a (non-mock) class that implements IFileSystem by calling the actual File.OpenRead() and File.OpenWrite() methods and use this one in the production code. In the tests, you use a mock framework, as mentioned by #Digger (my personal preference is Moq, but I haven't tried Rhino Mocks, so I have nothing negative to say about it) to mock out IFileSystem and use the mock to verify that the methods were called with the correct serialized data.
EDIT: Per request, an example in NUnit with Moq (I don't have an IDE here, so it's untested; feel free to correct it):
[Test]
public void BObjectShouldBeSerializedToFile() {
var fileSystemMock = new Mock<IFileSystem>();
var stream = new MemoryStream();
fileSystemMock.Setup(f => f.OpenWrite("theFileNameYouExpect.txt")).Returns(new StreamWriter(stream)).Verifiable();
var manager = new Manager(fileSystemMock.Object);
manager.SaveObject(new BObject(...));
stream.Seek(0, SeekOrigin.Begin);
Assert.That(...); // Perform asserts on the stream contents here
fileSystemMock.Verify(); // Not really necessary, but verify that `OpenWrite` was called
}
It depends on how much logic is contained in your class, in my opinion.
If there's some complicated logic inside your manager, it makes sense to abstract your file operations as per Aasmund's suggestion so that the logic can be tested independently of the file system. I do this when something is finicky enough to warrant the extra dependencies.
On the other hand, if there's very little logic other than calling into your serialization/deserialization code, then it's often acceptable to skip the unit tests and run integration tests that test the full cycle (create a BObject in memory, persist it via calling SaveObject, read it back out using GetObject, ensure that it is equal/equivalent to the one you persisted in the first place).
If your build environment can't run integration tests, then I'd look into setting it up so that it's possible.

Strategies to mock a webservice

I'm implementing a client consuming a webservice. I want to reduce dependencies and decided to mock the webservice.
I use mockito, it has the advantage vs. EasyMock to be able to mock classes, not just interfaces. But that's not the point.
In my test, I've got this code:
// Mock the required objects
Document mDocument = mock(Document.class);
Element mRootElement = mock(Element.class);
Element mGeonameElement = mock(Element.class);
Element mLatElement = mock(Element.class);
Element mLonElement = mock(Element.class);
// record their behavior
when(mDocument.getRootElement()).thenReturn(mRootElement);
when(mRootElement.getChild("geoname")).thenReturn(mGeonameElement);
when(mGeonameElement.getChild("lat")).thenReturn(mLatElement);
when(mGeonameElement.getChild("lon")).thenReturn(mLonElement);
// A_LOCATION_BEAN is a simple pojo for lat & lon, don't care about it!
when(mLatElement.getText()).thenReturn(
Float.toString(A_LOCATION_BEAN.getLat()));
when(mLonElement.getText()).thenReturn(
Float.toString(A_LOCATION_BEAN.getLon()));
// let it work!
GeoLocationFetcher geoLocationFetcher = GeoLocationFetcher
.getInstance();
LocationBean locationBean = geoLocationFetcher
.extractGeoLocationFromXml(mDocument);
// verify their behavior
verify(mDocument).getRootElement();
verify(mRootElement).getChild("geoname");
verify(mGeonameElement).getChild("lat");
verify(mGeonameElement).getChild("lon");
verify(mLatElement).getText();
verify(mLonElement).getText();
assertEquals(A_LOCATION_BEAN, locationBean);
What my code shows is that I "micro-test" the consuming object. It's like I would implement my productive code in my test. An example for the result xml is London on GeoNames.
In my opinion, it's far too granular.
But how can I mock a webservice without giving everystep? Should I let the mock object just return a XML file?
It's not about the code, but the approach.
I'm using JUnit 4.x and Mockito 1.7
I think the real problem here is that you have a singleton that calls and creates the web service so it is difficult to insert a mock one.
You may have to add (possibly package level) access to the singleton class. For example if the constructor looks something like
private GeoLocationFactory(WebService service) {
...
}
you can make the constructor package level and just create one with a mocked web service.
Alternatively you can set the webservice by adding a setter method, although I don't like mutable Singletons. Also in that case you have to remember to unset the webservice afterwards.
If the webservice is created in a method you might have to make the GeoLocationFactory extensible to substitute the mock service.
You may also look into remove the singleton itself. There are articles online and probably here on how to do that.
you really want to be mocking the results returned from the webservice to the code that will be using the result. In your example code above you seem to be mocking mDocument but you really want to pass in an instance of mDocument that has been returned from a mocked instance of your webservice and assert that the locationBean returned from the geoLocationFetcher matches the value of A_LOCATION_BEAN.
The easiest option would be to mock the WebService client,
when(geoLocationFetcher.extractGeoLocationFromXml(anyString()))
.thenReturn("<location/>");
You can modify the code to read the response xml from the file system.
Sample code can be found here: Mocking .NET WebServices with Mockito