.NET MAUI Integration Testing - FileNotFoundException: Could not load file or assembly Microsoft.Maui.Essentials - entity-framework-core

Question

I'm attempting to integration test a .NET MAUI application utilizing entity framework core.
When the code gets to the line 'this.Database.EnsureCreated()', it gives a file not found exception.
The first thought was trying to reference Microsoft.Maui.Essentials, though when I search for it in NuGet, all I can find is Microsoft.Maui.Essentials.Ref.___ which doesn't seem compatible with my project.
If I try to install it, I get the error 'The package Microsoft.Maui.Essentials.Ref.any 6.0.547 has a package type DotnetPlatform that is incompatible with this project'
How can I resolve this error?
The full length exception is:
System.IO.FileNotFoundException: 'Could not load file or assembly 'Microsoft.Maui.Essentials, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified.'
Integration test code:
...
var options = new DbContextOptionsBuilder<DataContext>()
.UseInMemoryDatabase(databaseName: "Test_Database")
.Options;
var mockDataContext = new Mock<DataContext>(options);
mockDataContextCreator
.Setup(x => x.CreateDbContext())
.Returns(new DataContext(options));
...
DataContext.cs
public class DataContext : DbContext
...
public DataContext(DbContextOptions options)
: base(options)
{
SQLitePCL.Batteries_V2.Init();
if (!this.Database.EnsureCreated())
{
this.Database.Migrate();
}
}
The Database property is of type 'Microsoft.EntityFrameworkCore.Infrastructure.DatabaseFacade' and is defined in the base class 'DbContext'.
Integration Test CSPROJ File:
...
<PropertyGroup>
<TargetFramework>net6.0</TargetFramework>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>
<IsPackable>false</IsPackable>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="7.0.0" />
<PackageReference Include="Microsoft.Maui.Dependencies" Version="6.0.547" />
<PackageReference Include="Microsoft.Maui.Extensions" Version="6.0.547" />
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />
<PackageReference Include="Moq" Version="4.18.2" />
<PackageReference Include="NUnit" Version="3.13.3" />
<PackageReference Include="NUnit3TestAdapter" Version="4.2.1" />
<PackageReference Include="NUnit.Analyzers" Version="3.3.0" />
<PackageReference Include="coverlet.collector" Version="3.1.2" />
</ItemGroup>
...

Answer 1

The fix is surprisingly easy. Add UseMauiEssentials to your test project file. Alternatively you can utilize UseMaui, the difference is explained here.
At least this worked for me out-of-the-box within almost the same setup (xUnit). Took me few hours to find this after number of more complicated but not robust enough attempts.
One of my failing attempts was to add "Microsoft.Maui.Dependencies" NuGet package. I can see it in your original post. With the fix suggested this NuGet package is not needed.
<PropertyGroup>
<TargetFramework>net6.0</TargetFramework>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>
<UseMauiEssentials>true</UseMauiEssentials>
<IsPackable>false</IsPackable>
</PropertyGroup>