How to test if a connection to a Db is established successfully?

I want to write a unit-test which asserts a connection string is valid so that a conenction is established to a SQL Db.

if I have :

string connectionString = GetCOnenctionString();
bool conenctionEstablished = false;

How can I set 'conenctionEstablished' variable's value as a result of a check to a Db with the 'connectionSt开发者_StackOverflowring' provided?

So that I can use it in an Assert.

You could try to connect in a try/catch then set conenctionEstablished based on whether the connection succeeds or not.

It is not going to be a "pure" unit test because your database is real but any way. I would use a try catch block and after opening the connection execute a "select 1" statement with ExecuteNonQuery(). At the end of the try block set the flag to true.

There are different states available, look at this:

private static void OpenSqlConnection(string connectionString)
{
    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        connection.Open();
        Console.WriteLine("ServerVersion: {0}", connection.ServerVersion);
        Console.WriteLine("State: {0}", connection.State);
    }
}

there is an Enumeration called Connectionstate so you can assert if the connection is closed, open connecting ,etc.

Assert.AreEqual(ConnectionState.Connecting, sqlcon.State);

We could rather check, if the connection is open or not, by using the following code:

using System.Data;

if (conn.State == ConnectionState.Open)
{
    return true;
}
else 
{
    return false;
}