Entity Framework Connection error event

Little bit work to do, but this will help you i think:

Encapsulate you DbContext withing a fake-context and hide your DbSets. You build an new context which will be the context for you business-logic. This one doesn't give access to the DbSets, it shows custom-dbSets to the user. The main work will be to build the fake-context, which needs to have all methods you're using on the real dbSets.

/// <summary>
/// This sould no be used anywhere except in MyDbContext2
/// </summary>
public class MyDbContext : DbContext
{
    public DbSet<SomeTableClass> SomeTable { get; set; }
}

/// <summary>
/// This will be your context in the business-logic
/// </summary>
public class MyDbContext2
{
    private MyDbContext realDb;

    public MyDbContext2(string conStr)
    {
        realDb = new MyDbContext();
    }

    public MyDbSet<SomeTableClass> SomeFakeTable { get; set; }
}

/// <summary>
/// Fake-set with logging
/// </summary>
/// <typeparam name="T"></typeparam>
public class MyDbSet<T> where T : class
{
    private DbSet<T> dbSet;

    public MyDbSet(DbSet<T> realDbSet)
    {
        this.dbSet = realDbSet;
    }

    public List<T> ToList()
    {
        try
        {
            return dbSet.ToList();
        }
        catch (Exception e)
        {
            // Do some logging..
            throw;
        }
    }

    public T SingleOrDefault()
    {
        try
        {
            return dbSet.SingleOrDefault();
        }
        catch (Exception e)
        {
            // Do some logging..
            throw;
        }
    }
}

A good idea would be to rename you DbContext and introduce a the fake-one with the old name. This way Visual Studio will show you which methods you have to implement.