We're using Moq and I was wondering what the current role of virtual methods were in it-- in the post below dated 2008 it's clear you had to mark your methods as virtual in order for Moq to work (or inherit from an interface.)
Moq discussion
However, is this still the case in .Net 4.5, that you're required to use virutal methods in the class you want to mock? And does this also hold true when you create a wrapper class around a static method-- the wrapper class either inherits from an interface or the method in question needs to be marked virtual?
This hasn't changed in .NET 4 or 4.5. As the link you provided explains, Moq uses Castle Windsor Dynamic Proxy to generate a type derived from the type you wish to mock. Therefore, the standard rules of inheritance apply. The derived type generated by Moq can only intercept calls to methods that any normal derived class can override.
Related
I have a problem with dependency injection in my project. I use PRISM framework in my project and I chose Ioc container when create it. Link -> https://github.com/blackpantific/InstagroomEX
In my app.xaml file I associate the class and interface
protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
containerRegistry.RegisterForNavigation();
containerRegistry.RegisterForNavigation<WelcomeView, WelcomeViewModel>();
containerRegistry.RegisterForNavigation<RegistrationView, RegistrationViewModel>();
containerRegistry.RegisterForNavigation<LoginView, LoginViewModel>();
//regestering
containerRegistry.RegisterSingleton<IValidationService, ValidationService>();
}
But my page after initializing() doesn't appear at the screen. This is ViewModel constructor
public RegistrationViewModel(INavigationService navigationService, IUserDataService userDataService,
IValidationService validationService) :
base(navigationService)
{
_userDataService = userDataService;
_validationService = validationService;
}
Something wrong here. When I pass to the RegistrationViewModel() constructor another parameters besides INavigationService navigationService the RegistrationView page doesn't not displayed. What am I doing wrong?
Assuming that WelcomePage is displayed correctly and RegistrationPage is not, I think that Andres Castro is correct: Prism tries to resolve the IUserDataService which is not possible. In the debug output you should see a message that IUserDataService cannot be resolved.
(Note: The following is based on my experiences with Prism and Unity. This might hold for other Dependency Injection frameworks, but it's possible that other frameworks behave differently.)
Prism relies on a Dependency Injection (DI) framework, for example Microsofts Unity application block. What happens when you try to navigate to RegistrationPage is, that Prism (if you are using ViewModelLocator.AutowireViewModel="True") tries to determine the type of the viewmodel (by convention) and asks the underlying DI framework to resolve this type (i.e. create an instance). For each of the required constructors parameters of this type, then again the DI framework tries to resolve them. If the parameters require concrete types it will then try to resolve those. If the parametery require interface (or abstract) types, the DI framework will look at its registrations and if the types have been registered create instances according to this registrations (which in turn might involve resolving other types).
If - however - the parameter requires an interface type which has not been registered, the DI framework does not know how to handle the situation. It coulld of course assume null, but this might lead to errors that might be way harder to track down, hence it will throw an exception (which is swallowed and Logged by Prism).
Now how can you handle the situation?
You'll need to tell the DI framework how to resolve IUserDataInterface. Since RegistrationPageViewModel does not actually use it, you could register null
containerRegistry.RegisterInstance<IValidationService>(null);
Could be irritating later, though. I'd rather remove the dependency of RegistrationPageViewModel to IUserDataService altogether - for now and add it later when it's actually used - or create a mock/stub that implements IUserDataService and is used as long there is no real implementation. This would be registered with the DI framework as you did with IValidationService.
Still exploring the new ASP.NET MVC5, now with build in DI!
No Problem so far, I can just inject my Handlers (I don't like the Term Service, since this defines to me a Platform-Neutral Interface):
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddApplicationInsightsTelemetry(Configuration);
services.Configure<Model.Meta.AppSettings>(Configuration.GetSection("AppSettings"));
services.AddSingleton(typeof(Logic.UserEndPointConfigurationHandler));
services.AddSingleton(typeof(Logic.NetworkHandler));
services.AddMvc();
}
Works fine, also the strongly typed Configuration-Object "AppSettings" works perfectly fine.
Also the Injection in the Controllers works as well.
But now my collaps: I seperated my DataAccess from the Handlers, and obviously I'd like to inject them as well:
public class UserEndPointConfigurationHandler
{
private readonly DataAccess.UserEndPointAccess _access;
public UserEndPointConfigurationHandler(DataAccess.UserEndPointAccess access)
{
_access = access;
}
But bam, UserEndPointAccess can't be resolved. So it seems like even I directly request to DI an Class with a Parameterless-Constructor, I need to register that. For this case, sure I should Interface and register them, but what does that mean for internal helper classes I also inject?
According to the Docs: http://docs.asp.net/en/latest/fundamentals/dependency-injection.html#recommendations and also the examples I found, all people in the world only seem to communicate between Controllers and some Repositories. No Business-Layer and no Classes on different Abstraction-Levels in Assemblies.
Is the Microsoft DI approach something totally differnt than the good ol' Unity one, where I can really decouple as fine granular as I'd like to?
Thanks in advance.
Matthias
Edit #Nightowl: I add my answer here, since it's a bit longer.
First of all, Unity does automatically create Instances, if I request a conecrete Type. This allows me to inject Types I register and Types, like Helper classes etc. I don't need to. This combination allows me to use DI everywhere.
Also in your Example I'd need to know the DataAcces in the WebGui, which is quite thight coupled. Well, I know there are solutions for this via Reflection, but I hoped Microsoft did something in this Topic, but probably that'd mean to big of a change.
Also allows Unity to store Instances or Instructions how to create them, another huge feature, which is missing at the moment.
Probably I'm just to spoiled, what refined DI-Libraries do, probably they also do to much, but at the moment the Microsoft-Implementation is just a huge downgrade according to my Information.
MVC Core follows the the composition root pattern, which is where object graphs are created based off of a set of instructions to instantiate them. I think you are misinterpreting what the IServiceCollection is for. It does not store instances, it stores instructions on how to create instances. The instances aren't actually created until a constructor somewhere in the object graph requests one as a constructor parameter.
So, in short the reason why your service (which you call UserEndPointAccess) is not being instantiated when you request it is because you have not configured the IServiceCollection with instructions on how to create it.
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddApplicationInsightsTelemetry(Configuration);
services.Configure<Model.Meta.AppSettings>(Configuration.GetSection("AppSettings"));
services.AddSingleton(typeof(Logic.UserEndPointConfigurationHandler));
services.AddSingleton(typeof(Logic.NetworkHandler));
// Need a way to instantiate UserEndPointAccess via DI.
services.AddSingleton(typeof(DataAccess.UserEndPointAccess));
services.AddMvc();
}
So it seems like even I directly request to DI an Class with a Parameterless-Constructor, I need to register that.
If you are doing DI correctly, each service class will only have a single constructor. If you have more than one it is known as the bastard injection anti-pattern, which essentially means you are tightly coupling your class definition to other classes by adding references to them as foreign defaults.
And yes, you need to register every type you require (that is not part of MVC's default registration). It is like that in Unity as well.
I am new to spring framework. Can anyone resolve the below issue.
I have too many model attribute methodes(#ModelAttribute) in a controller say A, now I want to use all these model attributes in other controllers but I donot want to extend controller A, so there any way to keep all these model attributes in common place where all the controllers can execute this on each call.
In Spring 3.2 you can use the #ControllerAdvice annotation to create a class with model attribute (and init binder, and exception handler) methods that apply to all controllers.
In older versions, instead of extending controller A, cannot you move the annotated methods to a new class and make it the parent of all the controller classes?
You can utilize interceptors to achieve this. Interceptor has access to ModelAndView, so you should just put what you need to model, in one of appropriate methods provided by interceptor.
More details:
Using Spring Interceptors in your MVC Webapp
Spring MVC handler interceptors example
With spring 3.2 we have the option to specify the basepackage where we want to intercept with #ControllerAdvice. Below is the link
http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/bind/annotation/ControllerAdvice.html
I assume that you are having a common model attribute method and a common model attribute bean.
If the spring you are using is having an old version then the least you can do is separate out the body of the method in a common utility.
The other solution is inheritance , you can create a super controller that has one model attribute and then extend that controller for actual implementations that you want. Keep common functionality in super controller and specific implementations in child classes.
I am using automapper to map a master class to various child classes.
Example: I have a class called VitalStatistics (master class). This class holds all fields for a record.
The company business rules indicate that only certain fields are needed based on the State location.
So, California may not all 20 fields found in the master class and may need only 10 fields instead of the 20. So I use automapper to map the VitalStatis class data to the CAVitalStats class which has only 10 fields. The TXVitalStats class may only have 3 fields. etc..
My web services need to return a type that these classes have in common. E.g. IVitalStatistics interface.
It seems as though the WCF service does not like an interface declared as the return type.
So, how can I get the service to return CAVitalStats or TXVitalStats? Normally if these both were of the same interface type then this would work because they all would be of type IVitalStatistics but the serialization messaging rules appear to have a problem with returning interface types.
I hope this made sense. Thanks
If you have CAVitalStats and TXVitalStats both inheriting from the same base class, for instance 'VitalStatsBase', then your service method could return VitalStatsBase.
To make this work with your 2 subclasses you'll need to use the KnownTypeAttribute in your service.
Below is a link describing the KnownTypeAttribute.
http://msdn.microsoft.com/en-us/library/ms730167.aspx
At a high level, how do these dep. injection frameworks work?
I can understand if you always instantiate an object via a custom factory like:
IUser user = DepInjector.Get<User>();
I'm guessing what happens is, wherever you defined the mappings, it will look at the type you want and try and find a match, if found, it will via reflection instantiate the type.
Are there dep. inj. frameworks that would work like:
IUser user = new User();
If so, how would it get the correct user, where is it hooking into the CLR to do this? In case of an asp.net website, is it any different?
If you want to know how Ninject works then the obvious place to start would be reading How Injection Works on their official wiki. It does use reflection but it now also uses dynamic methods:
"By default, the StandardKernel will
create dynamic methods (via
System.Reflection.Emit.DynamicMethod)
that can be used to inject values into
the different injection targets. These
dynamic methods are then triggered via
delegate calls."
As for you second example, I don't believe there are any DI frameworks that would do what you ask. However, constructor injection tends to be most common way of implementing IoC, so that when a class is constructed it knows what type to bind to via some configuration binding. So in your example IUser would be mapped to concrete User in config bindings so that any consuming class that has an IUser parameter as part of its constructor would get the correct User type passed in.
AFAIK there's no way to "hook into" object instantiation with the CLR. The only way to use DI in the second case would be to employ an assembly rewriter (i.e. a postprocessor similar to PostSharp) to replace the call to new with a call to the DI factory method (i.e. GetUser) in the compiled code.