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

Question

I am trying to test some exceptions in my project and one of the Exceptions I catch is SQlException.

It seems that you can\'t go new SqlException(

Answer 1

This should work:

SqlConnection bogusConn = 
    new SqlConnection("Data Source=myServerAddress;Initial
    Catalog=myDataBase;User Id=myUsername;Password=myPassword;");
bogusConn.Open();

That takes a bit before it throws the exception, so I think this would work even faster:

SqlCommand bogusCommand = new SqlCommand();
bogusCommand.ExecuteScalar();

Code brought to you by Hacks-R-Us.

Update: nope, the second approach throws an ArgumentException, not a SqlException.

Update 2: this works much faster (the SqlException is thrown in less than a second):

SqlConnection bogusConn = new SqlConnection("Data Source=localhost;Initial
    Catalog=myDataBase;User Id=myUsername;Password=myPassword;Connection
    Timeout=1");
bogusConn.Open();

Answer 2

I have a solution to this. I'm not sure whether it's genius or madness.

The following code will create a new SqlException:

public SqlException MakeSqlException() {
    SqlException exception = null;
    try {
        SqlConnection conn = new SqlConnection(@"Data Source=.;Database=GUARANTEED_TO_FAIL;Connection Timeout=1");
        conn.Open();
    } catch(SqlException ex) {
        exception = ex;
    }
    return(exception);
}

which you can then use like so (this example is using Moq)

mockSqlDataStore
    .Setup(x => x.ChangePassword(userId, It.IsAny<string>()))
    .Throws(MakeSqlException());

so that you can test your SqlException error handling in your repositories, handlers and controllers.

Now I need to go and lie down.