You can use a lambda with an input parameter, like so:

    .Returns((string myval) =&gt; { return myval; });

Or slightly more readable:

    .Returns&lt;string&gt;(x =&gt; x);


Even more useful, if you have multiple parameters you can access any/all of them with:

    _mock.Setup(x =&gt; x.DoSomething(It.IsAny&lt;string&gt;(),It.IsAny&lt;string&gt;(),It.IsAny&lt;string&gt;())
         .Returns((string a, string b, string c) =&gt; string.Concat(a,b,c));

You always need to reference all the arguments, to match the method&#39;s signature, even if you&#39;re only going to use one of them.

The generic `Returns&lt;T&gt;` method can handle this situation nicely.

    _mock.Setup(x =&gt; x.DoSomething(It.IsAny&lt;string&gt;())).Returns&lt;string&gt;(x =&gt; x);

Or if the method requires multiple inputs, specify them like so:

    _mock.Setup(x =&gt; x.DoSomething(It.IsAny&lt;string&gt;(), It.IsAny&lt;int&gt;())).Returns((string x, int y) =&gt; x);

How do I `grep` tab (\t) in files on the Unix platform?

grep a tab in UNIX

Which of the following is better?

    a instanceof B

or

    B.class.isAssignableFrom(a.getClass())

The only difference that I know of is, when &#39;a&#39; is null, the first returns false, while the second throws an exception. Other than that, do they always give the same result?

What is the difference between instanceof and Class.isAssignableFrom(...)?

I have a method on an interface:

    string DoSomething(string whatever);

I want to mock this with MOQ, so that it returns whatever was passed in - something like:

    _mock.Setup( theObject =&gt; theObject.DoSomething( It.IsAny&lt;string&gt;( ) ) )
       .Returns( [the parameter that was passed] ) ;

Any ideas?


Returning value that was passed into a method

I have a method on an interface:
<pre><code class="hljs language-c">string DoSomething(string whatever);
</code></pre>
I want to mock this with MOQ, so that it returns whatever was passed in - something like:
<pre><code class="hljs language-ini">_mock.Setup( theObject => theObject.DoSomething( It.IsAny&#x3C;string>( ) ) )
 .Returns( [the parameter that was passed] ) ;
</code></pre>
Any ideas?

How can I retrieve the item that is selected in a WPF-treeview? I want to do this in XAML, because I want to bind it.

You might think that it is `SelectedItem` but apparently that &lt;s&gt;does not exist&lt;/s&gt; is readonly and therefore unusable.

This is what I want to do:

    &lt;TreeView ItemsSource=&quot;{Binding Path=Model.Clusters}&quot; 
    			ItemTemplate=&quot;{StaticResource ClusterTemplate}&quot;
    			SelectedItem=&quot;{Binding Path=Model.SelectedCluster}&quot; /&gt;

I want to bind the `SelectedItem` to a property on my Model.

But this gives me the error:

&gt; &#39;SelectedItem&#39; property is read-only and cannot be set from markup.




**Edit:**
Ok, this is the way that I solved this:

    &lt;TreeView
    		  ItemsSource=&quot;{Binding Path=Model.Clusters}&quot; 
    		  ItemTemplate=&quot;{StaticResource HoofdCLusterTemplate}&quot;
    		  SelectedItemChanged=&quot;TreeView_OnSelectedItemChanged&quot; /&gt;


and in the codebehindfile of my xaml:

    private void TreeView_OnSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs&lt;object&gt; e)
    {
    	Model.SelectedCluster = (Cluster)e.NewValue;
    }

Data binding to SelectedItem in a WPF Treeview

I don&#39;t like to use XAML. I prefer to code everything in C#, but I think that I am doing things wrong.

In which cases it is better to use XAML and when do you use C#? What is your experience?

XAML or C# code-behind

I have a `byte[]` array that is loaded from a file that I happen to known contains [UTF-8][1].

In some debugging code, I need to convert it to a string. Is there a one-liner that will do this?

Under the covers it should be just an allocation and a *memcopy*, so even if it is not implemented, it should be possible.

  [1]: http://en.wikipedia.org/wiki/UTF-8




How to convert UTF-8 byte[] to string

    MyControl.Margin.Left = 10;
  
Error:
&gt; Cannot modify the return value of &#39;System.Windows.FrameworkElement.Margin&#39; because it is not a variable

Setting Margin Properties in code

I&#39;m trying to compare a time stamp from an incoming request to a database stored value. SQL Server of course keeps some precision of milliseconds on the time, and when read into a .NET DateTime, it includes those milliseconds. The incoming request to the system, however, does not offer that precision, so I need to simply drop the milliseconds.

I feel like I&#39;m missing something obvious, but I haven&#39;t found an elegant way to do it (C#).

How to truncate milliseconds off of a .NET DateTime

I&#39;d like to test an abstract class. Sure, I can [manually write a mock][1] that inherits from the class.

Can I do this using a mocking framework (I&#39;m using Mockito) instead of hand-crafting my mock? How?


  [1]: https://stackoverflow.com/questions/243274/best-practice-unit-testing-abstract-classes

Using Mockito to test abstract classes

Are there any libraries or methods to mock out the file system in C# to write unit tests? In my current case I have methods that check whether certain file exists and read the creation date. I may need more than that in future.

How do you mock out the file system in C# for unit testing?

I am beginning to believe that unit testing high level, well-written code, which requires extensive use of mock objects, has little to no value. I am wondering if this assertion is correct, or am I missing something?

*What do I mean by high level?* These are the classes and functions near the top of the food chain. Their input and output tends to be user input, and user interface. Most of their work consists of taking user input and making a series of calls to lower-level entities. They often have little or no meaningful return values.

*What do I mean by well-written?* In this case, I am referring to code that is decoupled from its dependencies (using interfaces and dependency injection), and line by line is at a consistent level of abstraction. There&#39;s no tricky algorithms, and few conditionals.

I **hate** writing unit tests for this kind of code. The unit tests consist almost entirely of mock object setup. Line by line, the unit test read almost like a mirror image of the implementation. In fact, I write the unit tests by looking at the implementation. &quot;First I assert this mock method is called, then I assert this mock method is called...&quot;, etc. **I should be testing the behavior of the method, not that it&#39;s calling the right sequence of methods**. Another thing: I have found that these tests are **extremely fragile to refactoring**. If a test is so brittle it utterly shatters and must be rewritten when the code under test is refactored, then hasn&#39;t one of the major benefits of unit testing been lost?

I don&#39;t want this post to be flagged as argumentative, or not a question. So I&#39;ll state my question directly: What is the correct way to unit test the kind of code I have described, or is it understood that **not everything needs a unit test**?



The value of high level unit tests and mock objects

I have a method call which I want to mock with mockito. To start with I have created and injected an instance of an object on which the method will be called. My aim is to verify one of the object in method call.

Is there a way that mockito allows you to assert or verify the object and it&#39;s attributes when the mock method is called?

example

    Mockito.verify(mockedObject)
           .someMethodOnMockedObject(
                  Mockito.&lt;SomeObjectAsArgument&gt;anyObject())

Instead of doing `anyObject()` i want to check that argument object contains some particular fields

    Mockito.verify(mockedObject)
           .someMethodOnMockedObject(
                  Mockito.&lt;SomeObjectAsArgument&gt;**compareWithThisObject()**)



Verify object attribute value with mockito

Is it possible to create a mock object that implements several interfaces with EasyMock?

For example, interface `Foo` and interface `Closeable`?

In Rhino Mocks you can provide multiple interfaces when creating a mock object, but EasyMock&#39;s `createMock()` method only takes one type.

Is it possbile to achieve this with EasyMock, without resorting to the fallback of creating a temporary interface that extends both `Foo` and `Closeable`, and then mocking that?

Is it possible to create a mock object that implements multiple interfaces with EasyMock?

Is it possible to assign an `out`/`ref` parameter using Moq (3.0+)?

I&#39;ve looked at using `Callback()`, but `Action&lt;&gt;` does not support ref parameters because it&#39;s based on generics. I&#39;d also preferably like to put a constraint (`It.Is`) on the input of the `ref` parameter, though I can do that in the callback.

I know that Rhino Mocks supports this functionality, but the project I&#39;m working on is already using Moq.

Assigning out/ref parameters in Moq

I am trying to test some exceptions in my project and one of the Exceptions I catch is `SQlException`.

It seems that you can&#39;t go `new SqlException()` so I am not sure how I can throw an exception especially without somehow calling the database (and since these are unit tests it is usually advised not to call the database since it is slow). 

I am using NUnit and Moq, but I am not sure how to fake this.

Responding to some of the answers that seem to all be based on ADO.NET, note that I am using Linq to Sql. So that stuff is like behind the scenes. 

More info as requested by @MattHamilton:

&lt;!-- language: lang-none --&gt;

    System.ArgumentException : Type to mock must be an interface or an abstract or non-sealed class.       
      at Moq.Mock`1.CheckParameters()
      at Moq.Mock`1..ctor(MockBehavior behavior, Object[] args)
      at Moq.Mock`1..ctor(MockBehavior behavior)
      at Moq.Mock`1..ctor()

Posts to the first line when it tries to mockup

     var ex = new Mock&lt;System.Data.SqlClient.SqlException&gt;();
     ex.SetupGet(e =&gt; e.Message).Returns(&quot;Exception message&quot;);

How to throw a SqlException when needed for mocking and unit testing?

    [TestMethod]
    public void Home_Message_Display_Unknown_User_when_coockie_does_not_exist()
    {
        var context = new Mock&lt;HttpContextBase&gt;();
        var request = new Mock&lt;HttpRequestBase&gt;();
        context
            .Setup(c =&gt; c.Request)
            .Returns(request.Object);
        HomeController controller = new HomeController();
        
        controller.HttpContext = context; //Here I am getting an error (read only).
        ...
     }

my base controller has an overrride of the Initialize that get&#39;s this requestContext.  I am trying to pass this along but I am not doing something right. 

    protected override void Initialize(System.Web.Routing.RequestContext requestContext)
    {
        base.Initialize(requestContext);
    }

Where can I get more information on mocking my RequestContext and HttpContext using Moq?  I am trying to mock cookies and the general context.

How do I mock the HttpContext in ASP.NET MVC using Moq?

I couldn&#39;t find a way to do this, though this can be done by hand so why not with moq?

Mocking virtual readonly properties with moq

Consider this class:

    public class Content
    {      
       public virtual bool IsCheckedOut {get; private set;}
       public virtual void CheckOut()
       {
          IsCheckedOut = true;
       }

       public virtual void CheckIn()
       {
          //Do Nothing for now as demonstrating false positive test.
       }
    }

The Checkin method is intentionally empty.  Now i have a few test methods to verify the status of calling each method.

    [TestMethod]
    public void CheckOutSetsCheckedOutStatusToTrue()
    {
        Content c = new Content();    
        c.CheckOut();
        Assert.AreEqual(true, c.IsCheckedOut); //Test works as expected
    }
    
    [TestMethod]
    public void CheckInSetsCheckedOutStatusToFalse()
    {
        Content c = new Content();
        c.CheckIn();
        Assert.AreEqual(false, c.IsCheckedOut); //Test does not work as expected
    }

The 2nd test passes for the wrong reasons.  So how can i use mocking (moq) to verify that CheckIn is setting the IsCheckedOut property?

Thanks.

**EDIT**

To clarify: I have a method called CheckIn() whose job it is to set the IsCheckedOut status to false.  

You will see in my test code above that the Test will return false even if i do not set the property value to false;  This is expected, nothing wrong here.

I think my question specifically is How can i verify that the CheckIn() method has set the IsCheckedOut property to false?  This is what I would call behavioral verification.  

I believe some of the comments suggested doing something which amounts to state verification? If so I don&#39;t believe there is any value in mocking this part at all when we can simply use:

    Content c = new Content();    
    c.CheckIn();    
    Assert.AreEqual(false, c.IsCheckedOut); //State verification

Of course I may be wrong, so please help me clarify these concepts :)

Content Type	Original Author	Original Content on Stackoverflow
Question	Steve Dunn	View Question on Stackoverflow
Solution 1 - C#	mhamrah	View Answer on Stackoverflow
Solution 2 - C#	Steve	View Answer on Stackoverflow
Solution 3 - C#	William	View Answer on Stackoverflow

Returning value that was passed into a method

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Solution 3 - C#

What is the difference between instanceof and Class.isAssignableFrom(...)?

grep a tab in UNIX

Attributions