add-Migration 错误 没有为此 DbContext 配置数据库提供程序

Question

i am trying to add migration to a DbContext ,

add-migration initial -verbose

I get Error

No database provider has been configured for this DbContext. A provider can be configured by overriding the DbContext.OnConfiguring method or by using AddDbContext on the application service provider. If AddDbContext is used, then also ensure that your DbContext type accepts a DbContextOptions object in its constructor and passes it to the base constructor for DbContext.

i have two .netcore class library project and and ,netcore unit test project in my solution

1. Domain(Poco Classess)
2. Repository (.Net Core 2.1 , EntitiFrameworkCore 2.1.4)
3. RepositoryTest

here is my DataContext Class

 public class DataContext:DbContext
    {
        public DataContext(DbContextOptions<DataContext> option) : base(option)
        {

        }

        public DataContext()
        {

        }

    public DbSet<User> User { get; set; }
    public DbSet<Cart> Cart { get; set; }
    public DbSet<CatalogItem> CatalogItem { get; set; }
 }

a constructor with DbContextOptions object is already there .

what could be possibly the problem ?

and here is a class in test project.

 public class CustomerRepositoryIntegrationTest
    {
        [Fact]
        public void should_add_customer()
        {
            //Arrange
            var option = new DbContextOptionsBuilder<DataContext>()
            .UseSqlServer(@"Data Source=(LocalDb)\MSSQLLocalDB;Database=ecommerce;Integrated Security=SSPI").Options;

            //Act
            using (DataContext dataConext = new DataContext(option))
            {

                dataConext.Database.Migrate();
                customer actual = new Customer()
                dataConext.Customer.Add(actual);
                dataConext.SaveChanges();

                var expected = dataConext.Customer.FirstOrDefault();

                //Assert
                expected.Should().BeEquivalentTo(expected);
            }


            //Assert
        }
    }

Answer 1

create a class that implement IDesignTimeDbContextFactory in test project and set test project as startup project

public class TemporaryDataContextFactory : IDesignTimeDbContextFactory<DataContext>
{
    public DataContext CreateDbContext(string[] args)
    {
        var option = new DbContextOptionsBuilder<DataContext>()
        .UseSqlServer(@"Data Source=(LocalDb)\MSSQLLocalDB;Database=IbReport;Integrated Security=SSPI").Options;
        return new DataContext(option);
    }
}