Nsubstitute: How to set mock data for mock DbSet?

[surya19876]

Hi,

I have created a mockDbSet as
var mockSet = Substitute.For>();
and I have a function GetDbSetData(), which returns List Of MyEntity.
And DbContext as dbContext = Substitute.For();
dbContext.MyTable.Returns(mockSet);

When I debug this code and check dbContext, I am getting MyEntity's Result view as Empty: "Enumeration yielded no results".

Can anyone explain what should I do?

Updated:
```c#
public class RepoTest
{
public IMyDbContext _DbContext;
public IConfigurationRoot _configuration { get; set; }
protected ILogger _logger { get; set; }
public IRepository Repository { get; set; }
public RepoTest()
{
var data = GetDbSetData();
var mockSet = Substitute.For>();
mockSet.AddRange(data);
_DbContext = Substitute.For();
_DbContext.RAActionStatusHistory.Returns(mockSet);
_configuration = Substitute.For();
_logger = Substitute.For();
Repository = new Repository(_DbContext,_configuration,_logger);
}
public List GetDbSetData()
{
return new List
{
new MyEntity
{
// Setting Properties
},
new MyEntity
{
// Setting Properties
}
};
}
[Fact]
public async Task GetMarksById_nsubstitute()
{
try
{
//input
id=1;

            //action
            int results1 = await Repository.GetDataById(id).ConfigureAwait(false);

            //assert
            Assert.Equal(10, results1);
        }
        catch
        {
            throw;
        }
    }
}

```

[zvirja]

Could you please provide us with a Minimal, Complete, and Verifiable example of code that helps to reproduce the scenario?

[dtchepak]

Hi @surya19876,
Have you seen MSDN: Entity Framework Testing with a Mocking Framework (EF6 onwards)? I don't have experience with EF so I can't be of much help, but that article seems to be a great starting point.

[surya19876]

Hi @zvirja, I have updated the above comment and provided the code. Please have a look.

[surya19876]

Hi @dtchepak, I have seen this article but was not helpful as I am using .net core and entity framework core.

[MaLiN2223]

@surya19876 I'm also using .NET Core (2.0) with entity framework and this is what I did in order to get what you want:
https://gist.github.com/MaLiN2223/65c49045646ec771316093d718dc462f I hope it will help

[dtchepak]

Thanks @MaLiN2223 ! 😄

[dtchepak]

Closing this after @MaLiN2223's answer. Please re-open if you need more information.

[generik0]

@surya19876 I'm also using .NET Core (2.0) with entity framework and this is what I did in order to get what you want:
https://gist.github.com/MaLiN2223/65c49045646ec771316093d718dc462f I hope it will help
@MaLiN2223
Is it just me or is this no longer working with ef core latest. set.AsNoTracking().Returns(data) throws.. and cannot perform much of anything on the mock :-/

[dtchepak]

Hi @generik0,
I can't help directly as I've no EF experience sorry.
I did have a quick search around and found a couple of things that might help (depending on the exception you're getting):

• Workaround with a custom extension method. Found this linked from a comment on this SO post.
• Options for avoiding mocking EF

Hope that helps put you on the right track. If no one chimes in on this issue maybe head to StackOverflow and ask with the [entity-framework] tag so EF devs can find it.

Regards,
David