EF Core MoqQueryable Use MockQueryable.NSubstitute

A DbSet represents the collection of all entities in the context, or that can be queried from the database, of a given type. The DbSet objects are created from a DbContext using the DbContext.Set method.

The MockQueryable.NSubstitute provides BuildMockDbSet extension method that creates a mock of type DbSet.

Let's consider the following simple example which mocks the DbSet as shown below.

public static void Example1()
{
    var authors = new List<Author>
    {
        new Author { Name="Carson Alexander" },
        new Author { Name="Meredith Alonso" },
        new Author { Name="Arturo Anand" },
        new Author { Name="Gytis Barzdukas"},
        new Author { Name="Yan Li" },
    };

    var mock = authors.AsQueryable().BuildMockDbSet();
    var userRepository = new TestDbSetRepository(mock);

    var result = userRepository.GetAll();

    foreach (var author in result)
    {
        Console.WriteLine(author.Name);
    }
}

Let's execute the above example, and you will see the following output.

Carson Alexander
Meredith Alonso
Arturo Anand
Gytis Barzdukas
Yan Li