Fake DbConnection

This project aim to mock the Dbconnection to test your query WITHOUT a database.

I wrote this tool because I found that on many occasions is not a good idea and also is not possible to test your SQL commands against an in-memory provider like SQLite.

Sometimes you want to test: transactions, stored procedures, a DB schema, or a SQL dialect not supported by SQLite, in these cases, is almost impossible or very hard to create a valid SQLite database that can fit your tests.

Another good point for not testing with in-memory DB came from Jimmy Bogard, I suggest you to read this article: Avoid In-Memory Databases for Tests

In the situation where we cannot test with SQLite, what we can do, at least, is to check if the command is correctly created.

How to

1. Implement the IDbLogger to pass to the instance of MockedDbConnection OR use the ListLogger that log on a List.
2. Create a new instance the FakedDbConnection
3. Call your code
4. Check the result

    // Arrange
    var lst = new ListLogger();
    IDbConnection conn = new MockedDbConnection(lst);

    var sql = "SELECT TITLE FROM CUSTOMERS WHERE ID = @Id AND EMAIL = @EMail";
    var parms = new { Id = 1, EMail = "guest@nobody.com" };

    // Act
    var result = conn.Query<string>(sql, parms);

    // Assert
    Assert.NotNull(result); // return an empty list since theres no DataTable passed to the DbConnection constructor

    // Verify the SQL Command
    var cmd = lst.Log.Where(p => p.Type == DbLogItem.LogType.LogCommand && p.Message == "ExecuteDbDataReader").First();
    Assert.Equal(sql, cmd.Value);

    // Verify the Parameters
    Assert.Equal(parms.EMail, lst.Parameters.First(p => p.ParameterName == nameof(parms.EMail)).Value);
    Assert.Equal(parms.Id, lst.Parameters.First(p => p.ParameterName == nameof(parms.Id)).Value);

Optional

You can also pass a DataTable if you want to mock the results.

Logger

You can write your own IDbLogger implementation to retrive only what you want

    public interface IDbLogger
    {
        void LogParameter(DbParameter parameter);
        
        void LogConnection(string message, string? value = null);
        
        void LogTransaction(string message, string? value = null);

        void LogCommand(string message, string? value = null);
    }