ExceptionFilter 單元測試 sample code

ApiExceptionFilterAttributeTests.cs

using static System.Web.Http.Hosting.HttpPropertyKeys;

namespace WebApplication1.CustomFilters.Tests
{
    [TestClass()]
    public class ApiExceptionFilterAttributeTests
    {
        private readonly ApiExceptionFilterAttribute _apiExceptionFilterAttribute = new ApiExceptionFilterAttribute();
        private HttpActionExecutedContext _context;

        [TestMethod()]
        public void when_exception_happened()
        {
            _context = GivenContext(new ThirdPartyException());

            WhenExceptionHappened();

            ResponseContentShouldBe(new ApiResponse { ErrorCode = ResponseStatusCode.GeneralError });
        }

        private void WhenExceptionHappened()
        {
            _apiExceptionFilterAttribute.OnException(_context);
        }

        private void ResponseContentShouldBe(ApiResponse expected)
        {
            var actual = _context.Response.Content.ReadAsAsync<ApiResponse>().Result;
            expected.ToExpectedObject().ShouldEqual(actual);
        }

        private HttpActionExecutedContext GivenContext(Exception exception)
        {
            return CreateExecutedContext(exception);
        }

        private HttpActionExecutedContext CreateExecutedContext(Exception exception)
        {
            return new HttpActionExecutedContext
            {
                ActionContext = new HttpActionContext
                {
                    ControllerContext = new HttpControllerContext
                    {
                        Request = GetHttpRequestMessage()
                    }
                },
                Exception = exception,
                Response = new HttpResponseMessage()
            };
        }

        private HttpRequestMessage GetHttpRequestMessage()
        {
            var request = new HttpRequestMessage();
            request.Properties[HttpConfigurationKey] = new HttpConfiguration();

            return request;
        }
    }
}