If the project being tested references Autofac 6.40 then a test project using FluentAssertions.Autofac 6.5.1 will fail. But it just needs a redirect in the app.config: <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <dependentAssembly> <assemblyIdentity name="Autofac" publicKeyToken="17863af14b0044da" culture="neutral" /> <bindingRedirect oldVersion="6.3.0.0" newVersion="6.4.0.0" /> </dependentAssembly> </assemblyBinding> </runtime> So this can be closed