So let's say I have a test that looks something like
[TestMethod]
[Asynchronous]
public void MyTest() {
MyObject m = new MyObject();
m.DoAsyncStuff();
EnqueueConditional(() => m.TaskComplete);
EnqueueCallback(() => Assert.IsTrue(m.ValidState));
EnqueueTestComplete();
}
How does EnqueueConditional work? Assume MyObject has no property change notifiers or anything. I'm assuming EnqueueConditional polls the variable periodically? But I'm not sure.
That's precisely what it does. It polls the m.TaskComplete variable multiple times a second (I'm not sure how many). It's a hack, and you wouldn't want it in production code, but it works for a testing framework, and it sure as heck simplifies a lot of other code.
For example, in production code, you'd probably want to make MyObject implement INotifyPropertyChanged, and then use Reactive Extensions to subscribe to the INPC notifications. But that would be a lot of extra work for the sort of simple conditionals that are everywhere in testing code, and I think that Jeff Wilcox made the right call in how he implemented this, however hacky it might be.
Related
I'd like to ask what are your thought on deprecation of the TableRegistry::get() static call in CakePHP 3.6?
In my opinion it was not a good idea.
First of all, using LocatorAwareTrait is wrong on many levels. Most important, using traits in such way can break the Single Responsibility and Separation of Concerns principles. In addition some developers don't want to use traits as all because they thing that it breaks the object oriented design pattern. They prefer delegation.
I prefer to use delegation as well with combination of flyweight/singleton approach. I know that the delegation is encapsulated by the LocatorAwareTrait but the only problem is that it exposes the (get/set)TableLocator methods that can be used incorrectly.
In other words if i have following facade:
class Fruits {
use \Cake\ORM\Locator\LocatorAwareTrait;
public function getApples() { ... }
public function getOranges() { ... }
...
}
$fruits = new Fruits();
I don't want to be able to call $fruits->getTableLocator()->get('table') outside of the scope of Fruits.
The other thing you need to consider when you make such changes is the adaptation of the framework. Doing TableRegistry::getTableLocator()->get('table') every time i need to access the model is not the best thing if i have multiple modules in my application that move beyond simple layered architecture.
Having flyweight/singleton class like TableRegistry with property get to access desired model just makes the development more straight forward and life easier.
Ideally, i would just like to call TR::get('table'), although that breaks the Cake's coding standards. (I've created that wrapper for myself anyways to make my app bullet proof from any similar changes)
What are your thoughts?
I've been looking into the feasability of using Reactive UI in production code. Some of the features are really appealing, but I have concerns about taking a dependency on this library. These include:
Whacky naming and conventions. For example, protected members starting with lower case, and the RaiseAndSetIfChanged method depends on your private member beginning with an underscore. I understand Paul Betts (ReactiveUI author) has a Ruby background, so I guess that's where the odd naming stems from. However, this will cause a real issue for me, since standard naming (as per Stylecop) is enforced throughout my project. Even if it wasn't enforced, I'd be concerned by the resultant inconsistency in naming that this will cause.
Lack of documentation/samples. There is some documentation and a lonely sample. However, the documentation is just a series of (old) blog posts and the sample is based on V2 of the library (it's now on V4).
Odd design, in parts. For example, logging is abstracted so as not to take a dependency on a specific logging framework. Fair enough. However, since I use log4net (and not NLog) I will need my own adapter. I think that will require me to implement IRxUIFullLogger, which has a metric crapload of methods in it (well over 50). I would have thought a far better approach would be to define a very simple interface and then provide extension methods within ReactiveUI to facilitate all the requisite overloads. In addition, there's this weird IWantsToRegisterStuff interface that the NLog assembly depends on, that I won't be able to depend on (because it's an internal interface). I'm hoping I don't need that...
Anyway, my concern here is the overall design of the library. Has anyone been bitten by this?
I'm already using MVVM Light extensively. I know Paul did a blog post where he explains you can technically use both, but my concern is more around maintainability. I suspect it would be horribly confusing having both intermingled in one's code base.
Does anyone have hands-on experience with using Reactive UI in production? If so, are you able to allay or address any of my above concerns?
Let's go through your concerns piece by piece:
#1. "Whacky naming and conventions."
Now that ReactiveUI 4.1+ has CallerMemberName, you don't have to use the conventions at all (and even then, you can override them via RxApp.GetFieldNameForPropertyFunc). Just write a property as:
int iCanNameThisWhateverIWant;
public int SomeProperty {
get { return iCanNameThisWhateverIWant; }
set { this.RaiseAndSetIfChanged(ref iCanNameThisWhateverIWant, value); }
}
#2. Lack of documentation/samples
This is legit, but here's some more docs / samples:
http://docs.reactiveui.net/ (this is the official ReactiveUI documentation, a work in progress but definitely where you want to start)
https://github.com/reactiveui/ReactiveUI.Samples
https://github.com/reactiveui/RxUI_QCon
https://github.com/play/play-windows
#3. "I would have thought a far better approach would be to define a very simple interface and then provide extension methods within ReactiveUI to facilitate all the requisite overloads"
Implement IRxUILogger instead, it has a scant two methods :) ReactiveUI will fill in the rest. IRxUIFullLogger is only there if you need it.
"In addition, there's this weird IWantsToRegisterStuff interface "
You don't need to know about this :) This is only for dealing with ReactiveUI initializing itself so that you don't have to have boilerplate code.
"I suspect it would be horribly confusing having both intermingled in one's code base."
Not really. Just think of it as "MVVM Light with SuperPowers".
I am answering as someone who has used ReactiveUI in a few production systems, has had issues with the way RxUI does stuff, and has submitted patches to try and fix issues I've had.
Disclaimer: I don't use all the features of RxUI. The reason being I don't agree with the way those features have been implemented. I'll detail my changes as I go.
Naming. I thought this was odd too. This ended up being one of the features I don't really use. I use PropertyChanged.Fody to weave in the change notification using AOP. As a result my properties look like auto properties.
Doco. Yes there could be more. Especially with the newer parts like routing. This possibly is a reason why I don't use all of RxUI.
Logging. I've had issues with this in the past. See pull request 69. At the end of the day I see RxUI as a very opinionated framework. If you don't agree with that opinion you can suggest changes, but that's all. Opinionated does not make it bad.
I use RxUI with Caliburn Micro. CM handles View-ViewModel location and binding, Screen and Conductors. I don't use CM's convention binding. RxUI handles Commands, and ViewModel INPC code, and allows me to react to property changes using Reactive instead of the traditional approaches. By keeping these things separate I find it much easier to mix the two together.
Does any of these issues have anything to do with being production ready? Nope. ReactiveUI is stable, has a decently sized user base, problems get solved quickly in the google group and Paul is receptive to discussion.
I use it in production and so far RxUI has been perfectly stable. The application has had problems with stability, some to do with EMS, others with an UnhandledException handler that was causing more problems than it was solving, but I've not had any problems with the ReactiveUI part of the application. However, I have had issues regarding the ObservableForProperty not firing at all, which I may have used incorrectly and did work consistently (incorrectly) in my test code as well as in the UI at run time.
-1. Paul explains that the _Upper is due to using reflection to get at the private field in your class. You can either use a block such as below to deal with the StyleCop and Resharper messages, which is easy to generate (from the Resharper SmartTag)
/// <summary>The xxx view model.</summary>
public class XXXViewModel : ReactiveObject
{
#pragma warning disable 0649
// ReSharper disable InconsistentNaming
[SuppressMessage("StyleCop.CSharp.NamingRules",
"SA1306:FieldNamesMustBeginWithLowerCaseLetter",
Justification = "Reviewed. ReactiveUI field.")]
private readonly bool _IsRunning;
[SuppressMessage("StyleCop.CSharp.NamingRules",
"SA1306:FieldNamesMustBeginWithLowerCaseLetter",
Justification = "Reviewed. ReactiveUI field.")]
private string _Name;
....
or change your properties from the full
/// <summary>Gets or sets a value indicating whether is selected.</summary>
public bool IsSelected
{
get { return _IsSelected; }
set { this.RaiseAndSetIfChanged(x => x.IsSelected, value); }
}
to its component parts such as
/// <summary>Gets or sets a value indicating whether is selected.</summary>
public bool IsSelected
{
get { return _isSelected; }
set
{
if (_isSelected != value)
{
this.RaisePropertyChanging(x => x.IsSelected);
_isSelected = value;
this.RaisPropertyChanged(x=>x.IsSelected);
}
}
}
This pattern is also useful where you don't actually supply a "simple" property accessor, but may require a more derived variant where setting one value affects multiple others.
-2. Yes the documentation isn't ideal but I found that after Rx, picking up the RxUI samples was quite easy. I also note that the jumps from 2->4 seem to have all come with the changes to support Windows 8/Windows 8 Phone, and having picked up ReactiveUI for a Windows Store App then the DotNet 4.5 support is excellent. i.e. use of [CallerName] now means that you simply this.RaiseAndSetIFChanged(value) no need for the expression.
-3. I haven't any feedback on the logging side as I've not elected to use it.
-4. I've not mixed and matched with others frameworks either.
There's also a list of other contributors to ReactiveUI 4.2 at http://blog.paulbetts.org/index.php/2012/12/16/reactiveui-4-2-is-released/, including Phil Haack.
Been doing quite a bit of silverlight programming lately and loving it but of course silverlight is async so i am forced to setup an event handler to call when the async is complete. This works great of course but i am just getting lots of code... basically 2 methods for everycall that i require to a wcf service. I recently discovered the following
client.LoadClientsCompleted += (sender, e) =>
{
// My Code
};
client.LoadClientsAsync(clientID);
It seems to work, its using lambdas rather than a physically method. I understand that this doesn't change the working of the technology and its still async. but it seems to tidy up my code quite a lot.
I would love to hear any comments on weather i should be using this, are there any PROS and CONS using either?
As i say point the event directly at a new method works great as well but technically i have 2 methods for every call i make ... The code is growing :-)
Using the lambda way i at least keep my callback event within my current method although it only fires when complete. It seems to make things easier BUT are there any problems with this method?
One big pro is that lambdas can capture the value of variables from their surroundings:
client.LoadClientsCompleted += (sender, e) =>
{
// My Code
// your code can use clientID here
};
client.LoadClientsAsync(clientID);
Lets say I have this
_articlesService.SaveAsync(Model, AddressOf OnSaveCompleted)
The OnSaveCompleteMethod do a couple of things, obviously. Its a
Protected Overridable Sub OnSaveCompleted(ByVal asyncValidationResult As AsyncValidationResult)
In my unittest. I need to run a mocked SaveAsync, and have OnSaveCompleted called in anyway, because the method sends out events that I need to know have been sent.
Right now, the code just walks past that method, thus its never executed.
Need help solving this because I'm stuck right now.
If I understand your context right:
you have a class under test which uses an ArticlesService
your ArticlesService (a collaborating class) is responsible for sending some events
you want to verify that your class under test is behaving correctly
you want to do that by checking for the events.
If that's the case, you may be making your class responsible for more than it needs to be. You only need to verify that the ArticlesService was asked to SaveAsync. You don't need to worry about what the ArticlesService then went off and did.
Think of it this way. You are a Class-Under-Test. You have too much work to do, so you've asked some other people to help you. You have two choices. You can either chase them up, worrying about whether they're doing it right, or you can just trust them.
Rather than micro-managing classes, you can write a separate test which gives some examples of the way the ArticlesService will work, which will check that the ArticlesService is doing its job correctly. Your CUT's responsibility is to delegate that work effectively.
If you actually need the events to be raised so that your CUT can respond, that's a separate aspect of its behaviour, and you can do it with Moq's "Raise" method, documented in "Events", here:
http://code.google.com/p/moq/wiki/QuickStart
Edit: You can also use "CallBack", documented on the same link, to do stuff with the args being passed to you, including OnSaveCompleted. Not sure if it's going to help or not; it's tricky to see what you're doing without both the code and the failing test. Good luck anyway!
Close, but not exactly like that.
We don't actually send out an event in the ArticleService.
The method SaveAsync takes an Article to be saved, and a method to be called once the saving is complete.
The problem is that the "OnSaveCompleted"-method isnt being called. (This method exists in the View Model Base class, so the service isnt sending the event, the viewmodel is.).
But we have our own implementation of WCF-service proxies so this is probably what's messing with us, since we dont use the generated code.
Think we will have to rework our infrastructure on the services abit to solve this.
So it's a special case, just wanted to throw the question out just in case. :)
Thanks anyway for the answer.
This might be a bit out there, but suppose I want to use Moq in a ViewModel to create some design time data, like so:
public class SomeViewModel
{
public SomeViewModel(ISomeDependency dependency)
{
if (IsInDesignMode)
{
var mock = new Mock<ISomeDependency>();
dependency = mock.Object; // this throws!
}
}
}
The mock could be set up to do some stuff, but you get the idea.
My problem is that at design-time in Blend, this code throws an InvalidCastException, with the message along the lines of "Unable to cast object of type 'Castle.Proxies.ISomeDependencyProxy2b3a8f3188284ff0b1129bdf3d50d3fc' to type 'ISomeDependency'." While this doesn't necessarily look to be Moq related but Castle related, I hope the Moq example helps ;)
Any idea why that is?
Thanks!
I'm having a similar issue, except that the cast is coming from a dynamically generated assembly (Blend_RuntimeGeneratedTypesAssembly) type that is masquerading as one of my types.
For no apparent reason.
Which is driving me CRAZY.
I used to think that I needed to do this sort of trick but after much experiementing and searching about, discovered that Blend 4 now can create design time sample datacontexts based on an existing class.
This effectively gives you a dummy class that looks just like your VM class so that you can add your binding etc.
It works well enough that this is the technique we now recommend.
A possible disadvantage with this is that if you need your real VM to perform some sort of interactivity then the proxy of course can't do that - you'd have to manually change values, or swap to another design time object. But in practice, I've rarely encountered this scenario. Most of the time, you set the state of the VM and then take ages getting the look right.
Update: released on github: https://github.com/GeniusCode/GeniusCode.Components.DynamicDuck
I also ran into a similar problem when trying to use castle to mock viewmodels at design time. We wrote our own msil duck / mock library, and it works well for that purpose.
I blogged about it here: http://blogs.geniuscode.net/JeremiahRedekop/?p=255
We are working to release the library under MS-PL and deploy on GitHub.