DrMock.EFCore 1.0.2

.NET 5.0 This package targets .NET 5.0. The package is compatible with this framework or higher. .NET Standard 2.0 This package targets .NET Standard 2.0. The package is compatible with this framework or higher. 
dotnet add package DrMock.EFCore --version 1.0.2
                    


                    

                
NuGet\Install-Package DrMock.EFCore -Version 1.0.2
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package. 
<PackageReference Include="DrMock.EFCore" Version="1.0.2" />
For projects that support PackageReference, copy this XML node into the project file to reference the package. 
<PackageVersion Include="DrMock.EFCore" Version="1.0.2" />
                    


                            Directory.Packages.props
                        

                    

                
<PackageReference Include="DrMock.EFCore" />
                    


                            Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package. 
paket add DrMock.EFCore --version 1.0.2
                    


                    

                
#r "nuget: DrMock.EFCore, 1.0.2"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package. 
#:package DrMock.EFCore@1.0.2
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package. 
#addin nuget:?package=DrMock.EFCore&version=1.0.2
                    


                            Install as a Cake Addin
                        

                    

                
#tool nuget:?package=DrMock.EFCore&version=1.0.2
                    


                            Install as a Cake Tool

DrMock.EfCore

A Superset of Moq which allow quick, easy and clear testing with Entity Framework Core!

The package is designed to quickly write readable methods to test your CRUD logic with test data without having to do integration tests or manually hard code test data for every test. It contains a fluent API to allow you to quickly randomise data but keep it relevant to the test you're writing - for example easily write data where something exists or doesn't.

A Brief History

It's always been a frustration of mine that we learn TDD with a 'Plus 2 values' or similar piece of logic. In reality we rarely get logic that we can Unit Test in such an isolated way, and often work on CRUD apps that have logic around which database entity you create or not. These become very difficult to test and my first attempt at solving this problem was to write out reams and reams of hardcoded test data that all the tests shared. Inevitably this was difficult to manage and it was difficult to reuse the same data for multiple tests, not to mention this breaks the rules of isolation in Unit Tests.

So I've been working on this pattern and honing it for a few years now, and finally got to the point where I have it in a reusable library, save having to recreate all the different classes! Making it generic was quite a challenge, and Entity Framework has a lot of inconsistencies so i've tried to make the API consistent regardless of this. I hope you find this library as useful as I will!

How to Use

You can install DrMock.EFCore from Nuget Package Manager or Nuget CLI:

nuget install DrMock.EFCore

Or you can use the dotnet CLI:

dotnet add package DrMock.EFCore

I have also created a seperate package called DrMock.EFCore.Base which contains the key interface you need to inherit from in your injected DatabaseContext. The reason for this being seperated is so you can install only that on your production code, and it's much more lightweight as a result. So I suggest install that practice on your code, and install DrMock.EFCore in your Test project.

Getting Started

Make sure to inherit from the interface IDbContext on your DbContext. You shouldn't need to generate any further code in order to implement this, it has all the key EF Core methods:

public class ContosoDbContext : DbContext, IDbContext
{
    public virtual DbSet<Person> People { get; set; }

    public virtual DbSet<Payroll> Payrolls { get; set; }

    public virtual DbSet<Department> Departments { get; set; }
}

Or for Inverting the dependency:

public interface IContosoDbContext : IDbContext
{
    public DbSet<Person> People { get; set; }

    public DbSet<Payroll> Payrolls { get; set; }

    public DbSet<Department> Departments { get; set; }
}

That's It, you're ready to write some tests!

Creating Test Data

To Mock your Interface, create an instance as follows:

var mockContext = new MockDbContext<IContosoDbContext>();

You can then chain a few different calls to ensure data is present:

var mockContext = new MockDbContext<IContosoDbContext>()
        .UseEntity<Department>()
        .WithRandomDataFor<Person>()
        .Include<Department>(hrDept, itDept);

You can also ensure all Entities are accessable with the following static method:

// Options is not required
var options = new MockDbContextOptions
    {
        MinItemsInDbSet = 20 // Means 20 items will be auto created for each entity
    };

var mockContext = MockDbContext<IContosoDbContext>.UseAllEntities(options);

A full breakdown of the Building Data Methods is as follows:

Method Name Example Code Definition
UseEntity .UseEntity<Person>() Ensures the DbSet can then be called within scope without causing null reference exceptions
WithRandomDataFor .WithRandomDataFor<Person>() As with UseEntity plus it generates random data to be queryable within a unit test scope of work
Include .Include(person1, person2) Allows you to manually input the queryable data
Exlude .Exlude(person1, person2) As with WithRandomDataFor but allows you to ensure unwanted values get removed
Exists .Exists<Person>(x => x.Id == 24 && x.fullName == "Joe Bloggs") As with Include but allows you to just declare the properties of interest
DoesNotExist .DoesNotExist<Person>(x => x.Id == invalidId) As with Exlude but allows you to just declare the properties of interest

Verifying Method Calls

Once you have declared the data your Unit Tests require, you can verify CRUD calls have been made...

There is a number of ready made Verify calls for each of the CRUD operation, such as:

// In your application code:
// Direct on the DbContext:
await _db.AddAync(newPerson);
// Or on the DbSet:
await _db.People.AddAsync(newPerson);

// In your Unit Test:
await mockDb.VerifyAddedAsync<Person>(x => x.FirstName == newPerson.FirstName && x.LastName == newPerson.LastName);

Note that there are 2 ways to call each CRUD method - directly on the Context, or via a DbSet. The Verification will handle either of these, but using both may cause issues.

Handling Exceptions

This library will allow you to write and test code for preventing conflicts such as duplicates. However no amount of server side code will remove the possibility of database conflicts. These usually occur in SaveChanges or SaveChangesAsync hence the following methods are provided for build time to allow handling these:

// For SaveChanges:
var mock = new MockDbContext<TestDbContext>()
    .UseEntity<Person>()
    .WithExceptionThrownOnSaveChanges<DataMisalignedException>();

// For SaveChangesAsync:
var mock = new MockDbContext<TestDbContext>()
    .UseEntity<Person>()
    .WithExceptionThrownOnSaveChangesAsync<ApplicationException>();

New Id Creation Callbacks

When creating entities with Add and AddAsync Entity Framework handily updates the class with the newly created key. You may then want to use this, possibly return it in the output. Hence the following methods to allow you to create Callbacks to mimic this:

// For Add:
var mock = new MockDbContext<ITestDbContext>()
                    .UseEntity<Department>()
                    .WithActionOnAdd<Department>(x => x.Id = expectedDepartmentId);
// For AddAsync:
var mock = new MockDbContext<ITestDbContext>()
                    .UseEntity<Department>()
                    .WithActionOnAddAsync<Department>(x => x.Id = expectedDepartmentId);

DrMock.EFCore is created by Jeph Bayfield and is licensed under the MIT license.

Product Compatible and additional computed target framework versions.
.NET net5.0 is compatible.  net5.0-windows was computed.  net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 is compatible.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 is compatible.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed.  net9.0 was computed.  net9.0-android was computed.  net9.0-browser was computed.  net9.0-ios was computed.  net9.0-maccatalyst was computed.  net9.0-macos was computed.  net9.0-tvos was computed.  net9.0-windows was computed.  net10.0 was computed.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 is compatible. 
.NET Framework net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
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Version Downloads Last Updated
1.0.2 33 3/25/2026
1.0.1 30 3/25/2026
1.0.0 35 3/24/2026

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