Can i use VS2010 PrivateObject to access a static field inside a static class?

Question

Is it possible to get access to a private static field inside a static class, using the VS2010 Unit Test class PrivateObject ?

Let say i have the following class:

public static class foo
{
    private static bar;
}

Can i use PrivateObject to create a copy of foo, and then get the bar field?

Why do you need to access a private field in a unit test? It is generally not a best practice to do so. — CheeZe5, Mar 09 '11 at 16:04
I cannot change the tested code, however i do want to get data from a specific private field.... — Yiftach Tzur, Mar 09 '11 at 16:06
possible duplicate of [C# - Get Private Field from Static Class](http://stackoverflow.com/questions/628666/c-get-private-field-from-static-class) — Austin Salonen, Mar 09 '11 at 16:16
I get the impression this isn't for a unit test... voting to close as duplicate. — Austin Salonen, Mar 09 '11 at 16:16

score 32 · Answer 1 · answered Oct 20 '11 at 11:43

32

PrivateType class is analogous to PrivateObject for invoking private static members. Overloaded GetStaticFieldOrProperty methods may be used. http://msdn.microsoft.com/en-us/library/microsoft.visualstudio.testtools.unittesting.privatetype(v=VS.100).aspx

answered Oct 20 '11 at 11:43

Deepum

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InvokeStatic method should be used. – sh_kamalh Sep 18 '12 at 15:29

score 9 · Answer 2 · answered Dec 16 '13 at 20:32

The answer by Deepun can be very useful. I wanted to add a specific example to help people who come this way.

Class with private static member.

public class foo
{
   private static int bar;
}

Code to get value.

PrivateType pt = new PrivateType(typeof(foo));
int bar = (int)pt.GetStaticFieldOrProperty("bar");

Code to change value

PrivateType pt = new PrivateType(typeof(foo));
pt.SetStaticFieldOrProperty("bar", 10);

This will work regardless of the class being static or not.

score 7 · Accepted Answer · answered Mar 09 '11 at 16:17

The property value can be retreived using reflection. This will require the use of Type.GetField Method (String, BindingFlags) and the FieldInfo.GetValue Method

string propertyName = "bar";
FieldInfo fieldInfo = typeof(foo).GetField(propertyName, BindingFlags.NonPublic | BindingFlags.Static);
object fieldValue = fieldInfo.GetValue(null);

Can i use VS2010 PrivateObject to access a static field inside a static class?

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