blocks|key|3060509|text|真是个好问题。投票支持它。我也想知道答案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3060510|我所知道的最佳实践之一(suggested+by+Josh+Smith，感谢Gishu指出这一点)是让基视图模型类在OnPropertyChanged()方法中检查属性是否真正存在。例如：|offset|length|style|CODE|3060511|abstract+class+ViewModelBase
{
++++[Conditional("DEBUG")]
++++public+void+VerifyPropertyName(string+propertyName)
++++{
++++++++//+Verify+that+the+property+name+matches+a+real,++
++++++++//+public,+instance+property+on+this+object.
++++++++if+(TypeDescriptor.GetProperties(this)[propertyName]+==+null)
++++++++{
++++++++++++if+(this.ThrowOnInvalidPropertyName)
++++++++++++++++throw+new+ArgumentException(propertyName);

++++++++++++string+msg+=+"Invalid+property+name:+"+%2B+propertyName;
++++++++++++Debug.Fail(msg);
++++++++}
++++}

++++protected+void+OnPropertyChanged(string+propertyName)
++++{
++++++++VerifyPropertyName(propertyName);

++++++++PropertyChangedEventHandler+handler+=+this.PropertyChanged;
++++++++if+(handler+!=+null)
++++++++{
++++++++++++var+e+=+new+PropertyChangedEventArgs(propertyName);
++++++++++++handler(this,+e);
++++++++}
++++}
}|code-block|syntax|javascript|3060512|但是这并不能帮助您发现XAML中的拼写问题。嗯..。我不知道任何现有的解决方案。也许WPF+Disciples的人可以提点建议。我想我应该使用PresentationTraceSources.DataBindingSource并添加到他的TextWriterTraceListener的Listners集合实例中，然后监视输出。一旦我们的雷达上出现错误或警告，我们就应该不能通过测试。|3060513|找到了很好的例子：WPF+Snippet+-+Detecting+Binding+Errors|3060514|希望这能有所帮助。至少有一点:)。|3060515|干杯，安瓦卡。|3060516|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/magazine/dd419663.aspx|1|http://wpfdisciples.wordpress.com/|2|http://msdn.microsoft.com/en-us/library/system.diagnostics.presentationtracesources.databindingsource.aspx|3|http://msdn.microsoft.com/en-us/library/system.diagnostics.textwritertracelistener.aspx|4|http://www.switchonthecode.com/tutorials/wpf-snippet-detecting-binding-errors^0|0|1M|J|C|N|0|0|0|3Z|8|16|D|1|1Z|16|2|3B|N|3|0|9|12|4|0|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1B|8|@$D|1C|E|1D|F|G]]|9|@$D|1E|E|1F|1|1G]]|A|$]]|$1|H|3|I|5|J|7|1H|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1I|8|@$D|1J|E|1K|F|G]]|9|@$D|1L|E|1M|1|1N]|$D|1O|E|1P|1|1Q]|$D|1R|E|1S|1|1T]]|A|$]]|$1|O|3|P|5|6|7|1U|8|@]|9|@$D|1V|E|1W|1|1X]]|A|$]]|$1|Q|3|R|5|6|7|1Y|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|20|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]|12|$5|X|Y|Z|A|$10|13]]|14|$5|X|Y|Z|A|$10|15]]|16|$5|X|Y|Z|A|$10|17]]|18|$5|X|Y|Z|A|$10|19]]]]

Really good question. Voted it up. I would like to know the answer too.

One of the best practices I know (<a href="http://msdn.microsoft.com/en-us/magazine/dd419663.aspx" rel="nofollow noreferrer">suggested by Josh Smith</a>, thanks Gishu for pointing to this) is having base view model class to check in the <code>OnPropertyChanged()</code> method whether property really exists. E.g.:

<pre><code>abstract class ViewModelBase
{
 [Conditional("DEBUG")]
 public void VerifyPropertyName(string propertyName)
 {
 // Verify that the property name matches a real, 
 // public, instance property on this object.
 if (TypeDescriptor.GetProperties(this)[propertyName] == null)
 {
 if (this.ThrowOnInvalidPropertyName)
 throw new ArgumentException(propertyName);

 string msg = "Invalid property name: " + propertyName;
 Debug.Fail(msg);
 }
 }

 protected void OnPropertyChanged(string propertyName)
 {
 VerifyPropertyName(propertyName);

 PropertyChangedEventHandler handler = this.PropertyChanged;
 if (handler != null)
 {
 var e = new PropertyChangedEventArgs(propertyName);
 handler(this, e);
 }
 }
}
</code></pre>

But this wouldn't help you to find spelling problems in XAML. Hmm... I don't know any existing solution for this. Maybe guys from <a href="http://wpfdisciples.wordpress.com/" rel="nofollow noreferrer">WPF Disciples</a> could suggest something. I think I would go with <a href="http://msdn.microsoft.com/en-us/library/system.diagnostics.presentationtracesources.databindingsource.aspx" rel="nofollow noreferrer">PresentationTraceSources.DataBindingSource</a> and add to his <code>Listners</code> collection instance of <a href="http://msdn.microsoft.com/en-us/library/system.diagnostics.textwritertracelistener.aspx" rel="nofollow noreferrer">TextWriterTraceListener</a> and then monitor output. As soon as we get an error or warning on our radar we should fail a test. 

Found good example: <a href="http://www.switchonthecode.com/tutorials/wpf-snippet-detecting-binding-errors" rel="nofollow noreferrer">WPF Snippet - Detecting Binding Errors</a> 

Hope this helps. At least a bit :).

Cheers, Anvaka.

blocks|key|313698|text|正如Anvaka所指出的，为视图模型使用一个检查属性名称的基类可以帮助避免这个特定的问题(尽管它不会告诉您VM类何时执行自己的属性更改通知并忽略基类中的方法，因为我从来没有在我的代码中看到过类似的事情)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|313699|你可以(也应该)插装你的代码，这样不能工作的东西就会以你看得见的方式失败。这有点自相矛盾的是，如果你知道什么事情可能会失败，并且你观察了它们，它们就不会失败，因为你正在观察它们的事实将防止你犯下导致它们失败的错误(比如编写一个不总是返回模板的模板选择器)。|313700|但从根本上讲，视图就是UI，所以如果发现测试它的方法并不是测试UI的方法，我会感到非常惊讶。|313701|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

As Anvaka points out, using a base class for your view model that checks property names can help avoid this particular problem (though it won't tell you when your VM class does its own property-change notification and ignores the method in the base class, not that I've ever seen anything like that happen in my code).

And you can (and should) instrument your code so that things that aren't working fail in a way that's visible to you. The thing that's kind of paradoxical about this is that if you know what things may fail and you watch them, they won't, because the fact that you're watching them will keep you from making the mistakes that lead them to fail (like writing a template selector that doesn't always return a template).

But fundamentally, the view is the UI, so I would be pretty surprised to find methods of testing it that weren't also methods for testing the UI.

blocks|key|3273897|text|我知道这不是对你问题的直接回答。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3273898|如果你知道你期望绑定的控件元素的名称，你可以做一些类似下面的测试(使用nunit)。这是一个粗略的版本。但在这里，您使用表达式并显式测试该属性是否在绑定中|3273899|+[Test]
++++public+void+TestBindings()
++++{
++++++++TestBinding<IndividualSolutionViewModel,+string>(x+=>+x.Name,+"Name",+TextBlock.TextProperty);
++++}

++++private+void+TestBinding<TViewModel,TResult>(Expression<Func<TViewModel,+TResult>>+property,+string+elementName,+
++++++++DependencyProperty+dependencyProperty)
++++{
++++++++string+memberName+=+ExpressionHelper.GetPropertyName(property);+//+f.ex+v+=>+v.Name+will+return+Name
++++++++TestBinding(memberName,+elementName,+dependencyProperty);

++++}

++++private+void+TestBinding(string+memberName,+string+elementInControlName,+DependencyProperty+dependencyProperty)
++++{
++++++++//object+viewModel+=+new+IndividualSolutionViewModel();
++++++++var+view+=+new+IndividualSolutionView();

++++++++//Assert.That(view.DataContext,+Is.EqualTo(viewModel));

++++++++var+element+=+view.FindName(elementInControlName);
++++++++Assert.That(element,+Is.Not.Null,+string.Format("Unable+to+find+the+element+{0}+in+view+{1}",+elementInControlName,+view.Name));
++++++++Assert.That(element,+Is.InstanceOf(typeof(DependencyObject)));

++++++++var+binding+=+BindingOperations.GetBinding(element+as+DependencyObject,+dependencyProperty);
++++++++Assert.That(binding,+Is.Not.Null,+string.Format("Could+not+find+a+binding+for+the+control+{0}",+elementInControlName));

++++++++Assert.That(binding.Path.Path,+Is.EqualTo(memberName));
++++}|code-block|syntax|javascript|3273900|Ps。您必须将此代码添加到app.config中|3273901|<configSections>
++++<sectionGroup+name="NUnit">
++++++++<section+type="System.Configuration.NameValueSectionHandler"
+++++++++++++++++name="TestRunner"></section>
++++</sectionGroup>
</configSections>
<NUnit>
++++<TestRunner>
++++++++<add+value="STA"+key="ApartmentState"></add>
++++</TestRunner>
</NUnit>|3273902|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I know that this is not the direct answer to your question. 

If you know the name of the control element, that you expect to be bound against you can do something like the test below (using nunit). This is the rough version. But here you use expressions and explicitly test that the property is in a binding

<pre><code> [Test]
 public void TestBindings()
 {
 TestBinding&lt;IndividualSolutionViewModel, string&gt;(x =&gt; x.Name, "Name", TextBlock.TextProperty);
 }

 private void TestBinding&lt;TViewModel,TResult&gt;(Expression&lt;Func&lt;TViewModel, TResult&gt;&gt; property, string elementName, 
 DependencyProperty dependencyProperty)
 {
 string memberName = ExpressionHelper.GetPropertyName(property); // f.ex v =&gt; v.Name will return Name
 TestBinding(memberName, elementName, dependencyProperty);

 }

 private void TestBinding(string memberName, string elementInControlName, DependencyProperty dependencyProperty)
 {
 //object viewModel = new IndividualSolutionViewModel();
 var view = new IndividualSolutionView();

 //Assert.That(view.DataContext, Is.EqualTo(viewModel));

 var element = view.FindName(elementInControlName);
 Assert.That(element, Is.Not.Null, string.Format("Unable to find the element {0} in view {1}", elementInControlName, view.Name));
 Assert.That(element, Is.InstanceOf(typeof(DependencyObject)));

 var binding = BindingOperations.GetBinding(element as DependencyObject, dependencyProperty);
 Assert.That(binding, Is.Not.Null, string.Format("Could not find a binding for the control {0}", elementInControlName));

 Assert.That(binding.Path.Path, Is.EqualTo(memberName));
 }
</code></pre>

Ps. You have to add this to the app.config

<pre><code>&lt;configSections&gt;
 &lt;sectionGroup name="NUnit"&gt;
 &lt;section type="System.Configuration.NameValueSectionHandler"
 name="TestRunner"&gt;&lt;/section&gt;
 &lt;/sectionGroup&gt;
&lt;/configSections&gt;
&lt;NUnit&gt;
 &lt;TestRunner&gt;
 &lt;add value="STA" key="ApartmentState"&gt;&lt;/add&gt;
 &lt;/TestRunner&gt;
&lt;/NUnit&gt;
</code></pre>

blocks|key|316763|text|我想我已经想出了一些方法，可以使用简单的反射，并修改我过去使用过的一些代码(+FindBindingsRecursively方法的代码是由Martin+Bennedik的Enterprise+WPF+Validation+Control编写的)：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|316764|[TestMethod]
public+void+CheckWpfBindingsAreValid()
{
++++//+instansiate+the+xaml+view+and+set+DataContext
++++var+yourView+=+new+YourView();+
++++yourView.DataContext+=+YourViewModel;

++++FindBindingsRecursively(yourView,
++++++++++++delegate(FrameworkElement+element,+Binding+binding,+DependencyProperty+dp)
++++++++++++{
++++++++++++++++var+type+=+yourView.DataContext.GetType();

++++++++++++++++//+check+that+each+part+of+binding+valid+via+reflection
++++++++++++++++foreach+(string+prop+in+binding.Path.Path.Split('.'))
++++++++++++++++{
++++++++++++++++++++PropertyInfo+info+=+type.GetProperty(prop);
++++++++++++++++++++Assert.IsNotNull(info);
++++++++++++++++++++type+=+info.PropertyType;
++++++++++++++++}
++++});
}

private+delegate+void+FoundBindingCallbackDelegate(FrameworkElement+element,+Binding+binding,+DependencyProperty+dp);

private+void+FindBindingsRecursively(DependencyObject+element,+FoundBindingCallbackDelegate+callbackDelegate)
{
++++//+See+if+we+should+display+the+errors+on+this+element
++++MemberInfo[]+members+=+element.GetType().GetMembers(BindingFlags.Static+%7C
++++++++++++++++BindingFlags.Public+%7C
++++++++++++++++BindingFlags.FlattenHierarchy);

++++foreach+(MemberInfo+member+in+members)
++++{
++++++++DependencyProperty+dp+=+null;

++++++++//+Check+to+see+if+the+field+or+property+we+were+given+is+a+dependency+property
++++++++if+(member.MemberType+==+MemberTypes.Field)
++++++++{
++++++++++++FieldInfo+field+=+(FieldInfo)member;
++++++++++++if+(typeof(DependencyProperty).IsAssignableFrom(field.FieldType))
++++++++++++{
++++++++++++++++dp+=+(DependencyProperty)field.GetValue(element);
++++++++++++}
++++++++}
++++++++else+if+(member.MemberType+==+MemberTypes.Property)
++++++++{
++++++++++++PropertyInfo+prop+=+(PropertyInfo)member;
++++++++++++if+(typeof(DependencyProperty).IsAssignableFrom(prop.PropertyType))
++++++++++++{
++++++++++++++++dp+=+(DependencyProperty)prop.GetValue(element,+null);
++++++++++++}
++++++++}

++++++++if+(dp+!=+null)
++++++++{
++++++++++++//+Awesome,+we+have+a+dependency+property.+does+it+have+a+binding?+If+yes,+is+it+bound+to+the+property+we're+interested+in?
++++++++++++Binding+bb+=+BindingOperations.GetBinding(element,+dp);
++++++++++++if+(bb+!=+null)
++++++++++++{
++++++++++++++++//+This+element+has+a+DependencyProperty+that+we+know+of+that+is+bound+to+the+property+we're+interested+in.+
++++++++++++++++//+Now+we+just+tell+the+callback+and+the+caller+will+handle+it.
++++++++++++++++if+(element+is+FrameworkElement)
++++++++++++++++{
++++++++++++++++++++callbackDelegate((FrameworkElement)element,+bb,+dp);
++++++++++++++++}
++++++++++++}
++++++++}
++++}

++++//+Now,+recurse+through+any+child+elements
++++if+(element+is+FrameworkElement+%7C%7C+element+is+FrameworkContentElement)
++++{
++++++++foreach+(object+childElement+in+LogicalTreeHelper.GetChildren(element))
++++++++{
++++++++++++if+(childElement+is+DependencyObject)
++++++++++++{
++++++++++++++++FindBindingsRecursively((DependencyObject)childElement,+callbackDelegate);
++++++++++++}
++++++++}
++++}
}|code-block|syntax|javascript|316765|entityMap|0|LINK|mutability|MUTABLE|url|http://www.bennedik.de/2007/05/update-of-wpf-integration-for.html^0|13|N|2D|X|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

I think I've come up with something that may work using simple reflection, and adapting some code I've used in the past (the code for the <code>FindBindingsRecursively</code> method was written by Martin Bennedik's as part of his <a href="http://www.bennedik.de/2007/05/update-of-wpf-integration-for.html" rel="nofollow">Enterprise WPF Validation Control</a>):

<pre><code>[TestMethod]
public void CheckWpfBindingsAreValid()
{
 // instansiate the xaml view and set DataContext
 var yourView = new YourView(); 
 yourView.DataContext = YourViewModel;

 FindBindingsRecursively(yourView,
 delegate(FrameworkElement element, Binding binding, DependencyProperty dp)
 {
 var type = yourView.DataContext.GetType();

 // check that each part of binding valid via reflection
 foreach (string prop in binding.Path.Path.Split('.'))
 {
 PropertyInfo info = type.GetProperty(prop);
 Assert.IsNotNull(info);
 type = info.PropertyType;
 }
 });
}

private delegate void FoundBindingCallbackDelegate(FrameworkElement element, Binding binding, DependencyProperty dp);

private void FindBindingsRecursively(DependencyObject element, FoundBindingCallbackDelegate callbackDelegate)
{
 // See if we should display the errors on this element
 MemberInfo[] members = element.GetType().GetMembers(BindingFlags.Static |
 BindingFlags.Public |
 BindingFlags.FlattenHierarchy);

 foreach (MemberInfo member in members)
 {
 DependencyProperty dp = null;

 // Check to see if the field or property we were given is a dependency property
 if (member.MemberType == MemberTypes.Field)
 {
 FieldInfo field = (FieldInfo)member;
 if (typeof(DependencyProperty).IsAssignableFrom(field.FieldType))
 {
 dp = (DependencyProperty)field.GetValue(element);
 }
 }
 else if (member.MemberType == MemberTypes.Property)
 {
 PropertyInfo prop = (PropertyInfo)member;
 if (typeof(DependencyProperty).IsAssignableFrom(prop.PropertyType))
 {
 dp = (DependencyProperty)prop.GetValue(element, null);
 }
 }

 if (dp != null)
 {
 // Awesome, we have a dependency property. does it have a binding? If yes, is it bound to the property we're interested in?
 Binding bb = BindingOperations.GetBinding(element, dp);
 if (bb != null)
 {
 // This element has a DependencyProperty that we know of that is bound to the property we're interested in. 
 // Now we just tell the callback and the caller will handle it.
 if (element is FrameworkElement)
 {
 callbackDelegate((FrameworkElement)element, bb, dp);
 }
 }
 }
 }

 // Now, recurse through any child elements
 if (element is FrameworkElement || element is FrameworkContentElement)
 {
 foreach (object childElement in LogicalTreeHelper.GetChildren(element))
 {
 if (childElement is DependencyObject)
 {
 FindBindingsRecursively((DependencyObject)childElement, callbackDelegate);
 }
 }
 }
}
</code></pre>

blocks|key|318755|text|也有这种可能性，这可能会给你一些想法。THe的核心思想是将绑定到的属性名公开为静态字符串属性。如果绑定属性名称发生更改，则会出现编译错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|318756|我还没有机会亲自测试这项技术--但它看起来确实很有趣：|318757|http://www.codeproject.com/Articles/42036/Project-Metadata-Generation-using-T4|offset|length|318758|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|26|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@$F|R|G|S|1|T]]|A|$]]|$1|H|3|-4|5|6|7|U|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|E]]]]

There is also this possibility, that might give you some ideas. THe gist of the idea is property names that you would be binding to are exposed as static string properties. If a binding property name changed you would get a compilation error.

I have not had the opportunity to actually test this technique myself - but it does look interesting:

<a href="http://www.codeproject.com/Articles/42036/Project-Metadata-Generation-using-T4" rel="nofollow">http://www.codeproject.com/Articles/42036/Project-Metadata-Generation-using-T4</a>

In MVVM it is normal to connect View to the ViewModel with data binding.

Therefore if the name of a properties changes on one of the Model objects that is databound to there is no compiler error.

When the compiler will not stop a bug, the next thing I think of is “UnitTest”, However 

<blockquote>
 How do you unit test this without
 spending forever writing a GUI test?
</blockquote>

Is there a system that will check that all the properties that are bound to is valid, (without having to run the UI) that I can call in a unit test?

I am looking for something that will take the view, and then loop over all WPF controls, for each WPF control it will look at all the binding and check if they are valid. 

<hr>

By the way there have been a few good questions about how to make OnPropertyChanged safe, and/or how to test it (But done of these get down to the level of a WPF view.)

<ul>
<li><a href="https://stackoverflow.com/questions/1329138/how-to-make-databinding-type-safe-and-support-refactoring/1329275">How to make Databinding type safe and support refactoring</a> </li>
<li><a href="https://stackoverflow.com/questions/527602/automatically-inotifypropertychanged/527840#527840">Automatically INotifyPropertyChanged</a></li>
<li><a href="https://stackoverflow.com/questions/301809/workarounds-for-nameof-operator-in-c-typesafe-databinding">workarounds for nameof() operator in C#: typesafe databinding</a></li>
<li><a href="http://blog.ploeh.dk/2009/08/06/AFluentInterfaceForTestingINotifyPropertyChanged.aspx" rel="nofollow noreferrer">A Fluent Interface For Testing INotifyPropertyChanged</a></li>
<li><a href="http://classtester.codeplex.com/" rel="nofollow noreferrer">Automatic Class Tester</a> will test all simple proptites and INotifyPropertyChanged</li>
</ul>

<hr>

I have put a bounty on this question, as someone must have thought hard about the problem and come up with soltions.

In MVVM with WPF how do I unit test the link between the ViewModel and the View

在虚拟机中，使用数据绑定将视图连接到ViewModel是很正常的。因此，如果在数据绑定到的某个Model对象上更改了属性的名称，则不会出现编译器错误。但是，当编译器无法阻止bug时，我想到的下一件事就是“UnitTest”。如何在不花费时间编写图形用户界面测试的情况下对其进行单元测试？是否有一个系统可以检查绑定到的所有...

问在带有WPF的MVVM中，如何对ViewModel和视图之间的链接进行单元测试
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