XUnit mocked db connection dapper error, 'Object is not set to an instance of an object' when executing sql statement - unit-testing

Question

I am trying to unit test my service layer as advised by #NKosi Here. I am able to do the integration test successfully by implementing the actual factory implementation without mocking anything but can't do the unit test (by mocking IDbConnection and my SQL connection factory class) as Dapper query executing fails with the error 'Object not set to an instance of an object'.
My IDbConnection factory and its implementation is as follow
public interface IDbConnectionFactory
{
IDbConnection CreateConnection();
}
public class ConnectionSetings
{
public string Name { get; set; }
}
public class SqlConnectionFactory : IDbConnectionFactory
{
private readonly ConnectionSetings connectionSettings;
public SqlConnectionFactory(ConnectionSetings connectionSettings)
{
this.connectionSettings = connectionSettings;
}
public IDbConnection CreateConnection()
{
return new SqlConnection(connectionSettings.Name);
}
}
And the XUnit test is as follow
[Fact]
public void Get_RestaurantById_ReturnsRestaurant()
{
//Arrange
var connection = new Mock<IDbConnection>();
var dbConnectionFactory = new Mock<IDbConnectionFactory>();
dbConnectionFactory.Setup(x => x.CreateConnection()).Returns(connection.Object);
//Act
var result = new SqlRestaurantDataCL(dbConnectionFactory.Object).Get(1);
//Assert
result.Name.Equals("Test Name 1");
//Assert.Equal("Test Name 1", result.Name);
}
And the Service Layer is as follow
public class SqlRestaurantDataCL : IRestaurantDataCL
{
private readonly IDbConnectionFactory factory;
public SqlRestaurantDataCL(IDbConnectionFactory factory)
{
this.factory = factory;
}
public Restaurant Get(int id)
{
using (var connection = factory.CreateConnection())
{
var selectSql = #"SELECT * From Restaurants Where Id = #Id";
var restaurant = connection.QuerySingleOrDefault<Restaurant>(selectSql, new
{
id
});
return restaurant;
}
}
}
Following is the error screenshot

Answer 1

Following is the answer to my question if anyone is in similar situation. Before following this solution, I would suggest to read #NKosi comments above and consult #Mikhail's solution Here.
ServiceStack.OrmLite.Sqlite package added to use in memory appraoch
internal class InMemoryDatabase
{
private readonly OrmLiteConnectionFactory dbFactory = new OrmLiteConnectionFactory(":memory:", SqliteDialect.Provider);
public IDbConnection OpenConnection() => this.dbFactory.OpenDbConnection();
public void Insert<T>(IEnumerable<T> items)
{
using (var db = this.OpenConnection())
{
db.CreateTableIfNotExists<T>();
foreach (var item in items)
{
db.Insert(item);
}
}
}
}
Data Access layer is as follow
public IEnumerable<Restaurant> GetAll()
{
using (var connection = factory.CreateConnection())
{
//return connection.Query<Restaurant>("Select * From [dbo].[Restaurants] Order By Name");
return connection.Query<Restaurant>("Select * From Restaurant Order By Name");
}
}
Unit test is as follow
[Fact]
public void Get_RestaurantById_ReturnsRestaurant()
{
//Arrange
var restaurants = new List<Restaurant>
{
new Restaurant { Id = 1, Name = "Test Name 1", Cuisine = CuisineType.None},
new Restaurant { Id = 2, Name = "Test Name 2", Cuisine = CuisineType.French},
new Restaurant { Id = 3, Name = "Test Name 3", Cuisine = CuisineType.German},
new Restaurant { Id = 4, Name = "Test Name 4", Cuisine = CuisineType.Italian},
new Restaurant { Id = 5, Name = "Test Name 5", Cuisine = CuisineType.None}
};
var db = new InMemoryDatabase();
db.Insert(restaurants);
var connection = new Mock<IDbConnection>();
var dbConnectionFactoryMock = new Mock<IDbConnectionFactory>();
dbConnectionFactoryMock.Setup(c => c.CreateConnection()).Returns(db.OpenConnection());
//Act
var result = new SqlRestaurantDataCL(dbConnectionFactoryMock.Object).GetAll();
//Assert
result.Should().BeEquivalentTo(restaurants);
}