blocks|key|1853607|text|如果您正在进行TDD，那么事件测试可能会开始生成大量重复的代码。我写了一个事件监视器，它为这些情况提供了一种更简洁的单元测试编写方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1853608|var+publisher+=+new+PropertyChangedEventPublisher();

Action+test+=+()+=>
{
++++publisher.X+=+1;
++++publisher.Y+=+2;
};

var+expectedSequence+=+new[]+{+"X",+"Y"+};

EventMonitor.Assert(test,+publisher,+expectedSequence);|code-block|syntax|javascript|1853609|有关更多详细信息，请参阅我对以下内容的回答。|1853610|Unit+testing+that+an+event+is+raised+in+C#,+using+reflection|offset|length|1853611|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/2567047/unit-testing-that-an-event-is-raised-in-c-using-reflection/2697721#2697721^0|0|0|0|0|1O|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|X|8|@]|9|@$K|Y|L|Z|1|10]]|A|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

If you're doing TDD then event testing can start to generate a lot of repetitive code. I wrote an event monitor that enables a much cleaner approach to unit test writing for these situations.

<pre><code>var publisher = new PropertyChangedEventPublisher();

Action test = () =&gt;
{
 publisher.X = 1;
 publisher.Y = 2;
};

var expectedSequence = new[] { "X", "Y" };

EventMonitor.Assert(test, publisher, expectedSequence);
</code></pre>

Please see my answer to the following for more details.

<a href="https://stackoverflow.com/questions/2567047/unit-testing-that-an-event-is-raised-in-c-using-reflection/2697721#2697721">Unit testing that an event is raised in C#, using reflection</a>

blocks|key|1853682|text|下面是一个稍微修改过的Andrew代码，它不只是记录引发事件的顺序，而是计算一个特定事件被调用的次数。虽然它是基于他的代码，但我发现它在我的测试中更有用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1853683|[TestMethod]
public+void+Test_ThatMyEventIsRaised()
{
++++Dictionary<string,+int>+receivedEvents+=+new+Dictionary<string,+int>();
++++MyClass+myClass+=+new+MyClass();

++++myClass.PropertyChanged+%2B=+delegate(object+sender,+PropertyChangedEventArgs+e)
++++{
++++++++if+(receivedEvents.ContainsKey(e.PropertyName))
++++++++++++receivedEvents[e.PropertyName]%2B%2B;
++++++++else
++++++++++++receivedEvents.Add(e.PropertyName,+1);
++++};

++++myClass.MyProperty+=+"testing";
++++Assert.IsTrue(receivedEvents.ContainsKey("MyProperty"));
++++Assert.AreEqual(1,+receivedEvents["MyProperty"]);
++++Assert.IsTrue(receivedEvents.ContainsKey("MyOtherProperty"));
++++Assert.AreEqual(1,+receivedEvents["MyOtherProperty"]);
}|code-block|syntax|javascript|1853684|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Below is a slightly changed Andrew's code which instead of just logging the sequence of raised events rather counts how many times a specific event has been called. Although it is based on his code I find it more useful in my tests.

<pre><code>[TestMethod]
public void Test_ThatMyEventIsRaised()
{
 Dictionary&lt;string, int&gt; receivedEvents = new Dictionary&lt;string, int&gt;();
 MyClass myClass = new MyClass();

 myClass.PropertyChanged += delegate(object sender, PropertyChangedEventArgs e)
 {
 if (receivedEvents.ContainsKey(e.PropertyName))
 receivedEvents[e.PropertyName]++;
 else
 receivedEvents.Add(e.PropertyName, 1);
 };

 myClass.MyProperty = "testing";
 Assert.IsTrue(receivedEvents.ContainsKey("MyProperty"));
 Assert.AreEqual(1, receivedEvents["MyProperty"]);
 Assert.IsTrue(receivedEvents.ContainsKey("MyOtherProperty"));
 Assert.AreEqual(1, receivedEvents["MyOtherProperty"]);
}
</code></pre>

blocks|key|2067831|text|这是非常旧的，甚至可能不会被读取，但使用一些很酷的新.net特性，我创建了一个INPC+Tracer类，允许这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2067832|[Test]
public+void+Test_Notify_Property_Changed_Fired()
{
++++var+p+=+new+Project();

++++var+tracer+=+new+INCPTracer();

++++//+One+event
++++tracer.With(p).CheckThat(()+=>+p.Active+=+true).RaisedEvent(()+=>+p.Active);

++++//+Two+events+in+exact+order
++++tracer.With(p).CheckThat(()+=>+p.Path+=+"test").RaisedEvent(()+=>+p.Path).RaisedEvent(()+=>+p.Active);
}|code-block|syntax|javascript|2067833|请参阅要点：https://gist.github.com/Seikilos/6224204|offset|length|2067834|entityMap|0|LINK|mutability|MUTABLE|url|https://gist.github.com/Seikilos/6224204^0|0|0|6|14|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

This is very old and probably wont even be read but with some cool new .net features I have created an INPC Tracer class that allows that:

<pre><code>[Test]
public void Test_Notify_Property_Changed_Fired()
{
 var p = new Project();

 var tracer = new INCPTracer();

 // One event
 tracer.With(p).CheckThat(() =&gt; p.Active = true).RaisedEvent(() =&gt; p.Active);

 // Two events in exact order
 tracer.With(p).CheckThat(() =&gt; p.Path = "test").RaisedEvent(() =&gt; p.Path).RaisedEvent(() =&gt; p.Active);
}
</code></pre>

See gist: <a href="https://gist.github.com/Seikilos/6224204" rel="noreferrer">https://gist.github.com/Seikilos/6224204</a>

blocks|key|2067900|text|基于本文，我创建了这个简单的断言助手：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2067901|private+void+AssertPropertyChanged<T>(T+instance,+Action<T>+actionPropertySetter,+string+expectedPropertyName)+where+T+:+INotifyPropertyChanged
++++{
++++++++string+actual+=+null;
++++++++instance.PropertyChanged+%2B=+delegate+(object+sender,+PropertyChangedEventArgs+e)
++++++++{
++++++++++++actual+=+e.PropertyName;
++++++++};
++++++++actionPropertySetter.Invoke(instance);
++++++++Assert.IsNotNull(actual);
++++++++Assert.AreEqual(propertyName,+actual);
++++}|code-block|syntax|javascript|2067902|有了这个方法助手，测试就变得非常简单。|2067903|[TestMethod()]
public+void+Event_UserName_PropertyChangedWillBeFired()
{
++++var+user+=+new+User();
++++AssertPropertyChanged(user,+(x)+=>+x.UserName+=+"Bob",+"UserName");
}|2067904|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Based on this article, i have created this simple assertion helper :

<pre><code>private void AssertPropertyChanged&lt;T&gt;(T instance, Action&lt;T&gt; actionPropertySetter, string expectedPropertyName) where T : INotifyPropertyChanged
 {
 string actual = null;
 instance.PropertyChanged += delegate (object sender, PropertyChangedEventArgs e)
 {
 actual = e.PropertyName;
 };
 actionPropertySetter.Invoke(instance);
 Assert.IsNotNull(actual);
 Assert.AreEqual(propertyName, actual);
 }
</code></pre>

With this method helper, the test becomes really simple.

<pre><code>[TestMethod()]
public void Event_UserName_PropertyChangedWillBeFired()
{
 var user = new User();
 AssertPropertyChanged(user, (x) =&gt; x.UserName = "Bob", "UserName");
}
</code></pre>

blocks|key|2067958|text|我在这里做了一个扩展：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2067959|public+static+class+NotifyPropertyChangedExtensions
{
++++private+static+bool+_isFired+=+false;
++++private+static+string+_propertyName;

++++public+static+void+NotifyPropertyChangedVerificationSettingUp(this+INotifyPropertyChanged+notifyPropertyChanged,
++++++string+propertyName)
++++{
++++++++_isFired+=+false;
++++++++_propertyName+=+propertyName;
++++++++notifyPropertyChanged.PropertyChanged+%2B=+OnPropertyChanged;
++++}

++++private+static+void+OnPropertyChanged(object+sender,+PropertyChangedEventArgs+e)
++++{
++++++++if+(e.PropertyName+==+_propertyName)
++++++++{
++++++++++++_isFired+=+true;
++++++++}
++++}

++++public+static+bool+IsNotifyPropertyChangedFired(this+INotifyPropertyChanged+notifyPropertyChanged)
++++{
++++++++_propertyName+=+null;
++++++++notifyPropertyChanged.PropertyChanged+-=+OnPropertyChanged;
++++++++return+_isFired;
++++}
}|code-block|syntax|javascript|2067960|有这样的用法：|2067961|+++[Fact]
++++public+void+FilesRenameViewModel_Rename_Apply_Execute_Verify_NotifyPropertyChanged_If_Succeeded_Through_Extension_Test()
++++{
++++++++//++Arrange
++++++++_filesViewModel.FolderPath+=+ConstFolderFakeName;
++++++++_filesViewModel.OldNameToReplace+=+"Testing";
++++++++//After+the+command's+execution+OnPropertyChanged+for+_filesViewModel.AllFilesFiltered+should+be+raised
++++++++_filesViewModel.NotifyPropertyChangedVerificationSettingUp(nameof(_filesViewModel.AllFilesFiltered));
++++++++//Act
++++++++_filesViewModel.ApplyRenamingCommand.Execute(null);
++++++++//+Assert
++++++++Assert.True(_filesViewModel.IsNotifyPropertyChangedFired());

++++}|2067962|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I've made an extension here:

<pre><code>public static class NotifyPropertyChangedExtensions
{
 private static bool _isFired = false;
 private static string _propertyName;

 public static void NotifyPropertyChangedVerificationSettingUp(this INotifyPropertyChanged notifyPropertyChanged,
 string propertyName)
 {
 _isFired = false;
 _propertyName = propertyName;
 notifyPropertyChanged.PropertyChanged += OnPropertyChanged;
 }

 private static void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
 {
 if (e.PropertyName == _propertyName)
 {
 _isFired = true;
 }
 }

 public static bool IsNotifyPropertyChangedFired(this INotifyPropertyChanged notifyPropertyChanged)
 {
 _propertyName = null;
 notifyPropertyChanged.PropertyChanged -= OnPropertyChanged;
 return _isFired;
 }
}
</code></pre>

There is the usage:

<pre><code> [Fact]
 public void FilesRenameViewModel_Rename_Apply_Execute_Verify_NotifyPropertyChanged_If_Succeeded_Through_Extension_Test()
 {
 // Arrange
 _filesViewModel.FolderPath = ConstFolderFakeName;
 _filesViewModel.OldNameToReplace = "Testing";
 //After the command's execution OnPropertyChanged for _filesViewModel.AllFilesFiltered should be raised
 _filesViewModel.NotifyPropertyChangedVerificationSettingUp(nameof(_filesViewModel.AllFilesFiltered));
 //Act
 _filesViewModel.ApplyRenamingCommand.Execute(null);
 // Assert
 Assert.True(_filesViewModel.IsNotifyPropertyChangedFired());

 }
</code></pre>

I have some code that raises <code>PropertyChanged</code> events and I would like to be able to unit test that the events are being raised correctly.

The code that is raising the events is like

<pre><code>public class MyClass : INotifyPropertyChanged
{
 public event PropertyChangedEventHandler PropertyChanged; 

 protected void NotifyPropertyChanged(String info)
 {
 if (PropertyChanged != null)
 {
 PropertyChanged(this, new PropertyChangedEventArgs(info));
 }
 } 

 public string MyProperty
 {
 set
 {
 if (_myProperty != value)
 {
 _myProperty = value;
 NotifyPropertyChanged("MyProperty");
 }
 }
 }
}
</code></pre>

I get a nice green test from the following code in my unit tests, that uses delegates:

<pre><code>[TestMethod]
public void Test_ThatMyEventIsRaised()
{
 string actual = null;
 MyClass myClass = new MyClass();

 myClass.PropertyChanged += delegate(object sender, PropertyChangedEventArgs e)
 {
 actual = e.PropertyName;
 };

 myClass.MyProperty = "testing";
 Assert.IsNotNull(actual);
 Assert.AreEqual("MyProperty", actual);
}
</code></pre>

However, if I then try and chain the setting of properties together like so:

<pre><code>public string MyProperty
{
 set
 {
 if (_myProperty != value)
 {
 _myProperty = value;
 NotifyPropertyChanged("MyProperty");
 MyOtherProperty = "SomeValue";
 }
 }
}

public string MyOtherProperty
{
 set
 {
 if (_myOtherProperty != value)
 {
 _myOtherProperty = value;
 NotifyPropertyChanged("MyOtherProperty");
 }
 }
}
</code></pre>

My test for the event fails - the event that it captures is the event for the MyOtherProperty.

I'm pretty sure the event fires, my UI reacts like it does, but my delegate only captures the last event to fire.

So I'm wondering: 
1. Is my method of testing events correct? 
2. Is my method of raising chained events correct?

Unit testing that events are raised in C# (in order)

单元测试

我有一些引发PropertyChanged事件的代码，我希望能够单元测试事件是否被正确引发。引发事件的代码如下所示public class MyClass : INotifyPropertyChanged{   public event PropertyChangedEventHandler PropertyChang...

问在C#中(按顺序)引发事件的单元测试
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