ASP.NET: How to test linQ query

var vUser = (from u in this.dbName.aspnet_Users< br /> where u.UserName.Equals(this.wCreateUser.UserName)
 select u).Single();

StringBuilder sb = new StringBuilder();
StringWriter writer = new StringWriter(sb);
this.dcLAUNCHOnline.Log = writer;
//Execute Query..
//sb.ToString(); //will contain the sql produced by the LINQ Query

How to test a LINQ query as follows:

var vUser = (from u in this.dbName.aspnet_Users
 where u.UserName.Equals(this.wCreateUser.UserName)
 select u).Single ();

I keep getting the null exception of vUser, but I am pretty sure that such a user exists.

The record must exist or be in An exception must be thrown during lambda evaluation, otherwise the thrown exception will be

The sequence contains no elements.

< p>Are you accessing any properties on the vUser object after the query, or the this.wCreateUser object may be null?

Edit: Comment..

If the exception is that the sequence does not contain elements, the generated query does not return results. I suggest you check the generated query and test it directly against SQL Server.

You can do this in several ways.

>Open SQL Profiler and watch
the query being executed.
>Attach TextWriter to DataContext.Log So that you can see the output of the query
(e.g.
below)..
>use LINQPad as the suggested other answer.

.

p>

StringBuilder sb = new StringBuilder();
StringWriter writer = new StringWriter(sb);
this.dcLAUNCHOnline.Log = writer;
//Execute Query..
//sb.ToString(); //will contain the sql produced by the LINQ Query