Geting instance of class without reference to project

i have this scenerio:

I have two solutions and three projects:

Web.sln
|
|__ Core.csproj

//And

Common.sln
|
|__ Common.csproj
|
|__ Tests.csproj

In Common.Tests exist class (for example, Tests.cs) that implements interface from Common.Common (lets say ITests.cs) project. Project Web.Core have reference to Common.Common. So:

Web.Core References: Common.Common
Common.Tests References: Common.Common

I want use class mentioned before from Common.Tests in Web.Core but when i added reference (by Add Existing Project, then Add->Reference) to it, Web.Core starting to be broken.

Common.Tests and Web.Core uses same nugets and it starts to be broken too after adding reference to Common.Tests in Web.Core.

My question is, how to get that Tests.cs class in Web.Core project without adding straigh reference to Common.Tests? I need only instance of this class.