How can I write an automated test for exception handling

Question

I have a lot of the following type of code (each gets data from different tables).

public class TableOneDAO
{
    public TableOneDAO(IDbConnection dbConnection)
    {
        _dbConnection = dbConnection;
        _log = LogFacade.GetLog();
        _tableOneRowMapper = new TableOneRowMapper();
    }

    public IList<TableOneRecord> FindAll()
    {
        try
        {
            using (IDbCommand cmd = _dbConnection.CreateCommand())
            {
                cmd.CommandText = TableOneSql.FindAllSql();

                return _tableOneRowMapper.GetObjectList(cmd.ExecuteReader());
            }
        }
        catch (Exception exception)
        {
            _log.Error(exception.Message, exception);

            throw;
        }
    }

    private readonly IDbConnection _dbConnection;
    private readonly TableOneRowMapper_tableOneRowMapper;
    private readonly ILog _log;
}

_tableOneRowMapper.GetObjectList(cmd.ExecuteReader()) gets the the data from the database and maps it to a List. We have had past issues of records causing issues in the mapping and now want to log those right away and then trow them to the calling application. I have tests for everything but the exception handling. I must keep the generic exception handling in place.

I am using or have the following available to use:

• .Net 3.5
• VS 2008
• NUnit 2.5.10.11092
• Rhino Mocks 3.6

MY QUESTIONS:

• How can I create automated tests (unit or integration) for the exception handling?
• Do I need to inject the TableOneRowMapper and mock it so it throws an exception when called?
• Are there any other ways to do this without injecting it?
• Do I not worry about testing the exception handling?

Answer 1

? How can I create automated tests (unit or integration) for the exception handling?

// ensure that a given code block throws specific exception
Assert.Throws<ExceptionType>(() => { code block to execute });

// ensure that a given code block DOES NOT throw specific exception
Assert.DoesNotThrow(() => { code block to execute });

? Do I need to inject the TableOneRowMapper and mock it so it throws an exception when called?

• Unti test - yes, since it is a dependency you should inject it
• Integration test - no

? Are there any other ways to do this without injecting it?

No, otherwise it would be an integration test rather unit test

? Do I not worry about testing the exception handling?

???