Can not find system.web.http
问题 I have to add a system.web.http assembly reference because I added the HttpConfiguration class to my unit test class library project. When I browse the Add reference dialog I can not find the system.web.http assembly. The class library project has the .Net 4.5.1 framework targeted. 回答1: in order to get the system.web.http you will need to install a nuget package in the nuget command line: Install-Package Microsoft.AspNet.WebApi.Core https://www.nuget.org/packages/Microsoft.AspNet.WebApi.Core/