"Object Reference not set to an instance of an object" in unit testing using c#?

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Hi,
I am tring to unit test my project but it showing error as "Object Reference not set to an instance of an object". someone kindly give me a solution for this problem.
I referred all necessary namespace in this project.

C#

//Unit Test code

using System;

using Microsoft.VisualStudio.TestTools.UnitTesting;


using Software.Test;


namespace UnitTestProject
{

    [TestClass]

    public class UnitTest1
    {

        [TestMethod]

        public void TestMethod1()
        {
           ConnectionTests.TestConnection("https://sample.com");

           Guid id = ConnectionTests.TestConnectionSettings("https://sample.com", "Sample Test", "customer_name", "xyzasd");

        }
    }
}


   

 //Project used for unit testing
   
namespace Software.TestClient
{
   
    public static class ConnectionTests
    {
       
        public static void TestConnection(string Url)
        {
           	Source Con = null;
                appGlobal.AddText();
                appGlobal.AddText("Connecting " + Url + "...");
                Con = Source.Open(Url);
         }
           
     }


        public static Guid TestConnectionSettings(string Url, string Name, string customer, string Key)
        {
            ConnectionDetails det= new ConnectionDetails();
          
            det.data = "";
            det.url = Url;
           
           
                using (Software.Client.Source src = Software.Client.Source.Open(Url))
                {
                    src.StartConnection(key,Name);

                }
               
        }

Thanks
Karthik.R

Posted 1-Dec-14 23:26pm

Karthik Ravi

Updated 1-Dec-14 23:54pm

v2

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Comments

Kornfeld Eliyahu Peter 2-Dec-14 5:30am

On which line?

Karthik Ravi 2-Dec-14 5:43am

Guid id = ConnectionTests.TestConnectionSettings("https://sample.com", "Sample Test", "customer_name", "xyzasd"); on this line

Kornfeld Eliyahu Peter 2-Dec-14 5:48am

Source.StartConnection(key,Name);
You probably meant
src.StartConnection(key,Name);

Karthik Ravi 2-Dec-14 5:54am

ya its src.StartConnection(key,Name);

V. 2-Dec-14 5:41am

Is Source.Open a static function ?
It would help if you gave us more info (where does it break?) Did you step through?

Karthik Ravi 2-Dec-14 5:49am

Actually i am doing unit testing, i'm just calling the function "ConnectionTests.TestConnectionSettings()" present in the ConnectionTests class but result is failure. i think it may be on "Source Con" in TestConnection method.
I can't use break point because this project is not executable its a unit test project.

V. 2-Dec-14 5:52am

??? You can put a break point there if I'm not mistaken... Source Con = null is not wrong, I'm sure of that. You also haven't replied to my question. is Source.Open a static function? If not, then that's your culprit.

Karthik Ravi 2-Dec-14 5:56am

ya Source.Open is static

V. 2-Dec-14 6:02am

Maybe this: Software.Client.Source src = Software.Client.Source.Open(Url)
Isn't working and src is null... Again, debug and step through...

Richard MacCutchan 2-Dec-14 5:53am

You should step through the code with your debugger to isolate which object is the null reference.

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OriginalGriff · Answer 1 · 2014-12-02T00:13:00

"i think it may be on "Source Con" in TestConnection method. "

C#

Source Con = null;

Can't throw a null reference exception - it doesn't refer to or create an instance of any class.
However, then next line is likely to:

C#

appGlobal.AddText();

Check your references to appGlobal - the case on the name implies it is a variable, and if you haven't assigned a value to it yet then you will get a null reference exception.

Sergey Alexandrovich Kryukov · Answer 2 · 2014-12-02T05:19:00

You did not show where the exception with the message "Object reference not set to an instance of an object" is thrown. You should not ask a specific question each time you face this little problem. It's much more important to learn how to deal with it all by yourself in all cases.

Not to worry. This is one of the very easiest cases to detect and fix. It simply means that some member/variable of some reference type is dereferenced by using and of its instance (non-static) members, which requires this member/variable to be non-null, but in fact it appears to be null. Simply execute it under debugger, it will stop the execution where the exception is thrown. Put a break point on that line, restart the application and come to this point again. Evaluate all references involved in next line and see which one is null while it needs to be not null. After you figure this out, fix the code: either make sure the member/variable is properly initialized to a non-null reference, or check it for null and, in case of null, do something else.

Please see also: want to display next record on button click. but got an error in if condition of next record function "object reference not set to an instance of an object"[^].

Sometimes, you cannot do it under debugger, by one or another reason. One really nasty case is when the problem is only manifested if software is built when debug information is not available. In this case, you have to use the harder way. First, you need to make sure that you never block propagation of exceptions by handling them silently (this is a crime of developers against themselves, yet very usual). The you need to catch absolutely all exceptions on the very top stack frame of each thread. You can do it if you handle the exceptions of the type System.Exception. In the handler, you need to log all the exception information, especially the System.Exception.StackTrace:
http://msdn.microsoft.com/en-us/library/system.exception.aspx[^],
http://msdn.microsoft.com/en-us/library/system.exception.stacktrace.aspx[^].

The stack trace is just a string showing the full path of exception propagation from the throw statement to the handler. By reading it, you can always find ends. For logging, it's the best (in most cases) to use the class System.Diagnostics.EventLog:
http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx[^].

Good luck,

—SA

"Object Reference not set to an instance of an object" in unit testing using c#?

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