HandleCreateOrderSuccessfully creates an HTTP handler at `/orders` on the test handler mux that tests resource creation.

HandleDeleteOrderSuccessfully creates an HTTP handler at `/orders` on the test handler mux that tests resource deletion.

HandleGetOrderSuccessfully creates an HTTP handler at `/orders` on the test handler mux that responds with a single resource.

HandleListOrdersSuccessfully creates an HTTP handler at `/orders` on the test handler mux that responds with a list of two orders.

CreateRequest provides the input to a Create request.

GetResponse provides a Get result.

ListResponse provides a single page of RESOURCE results.

ExpectedOrdersSlice is the slice of orders expected to be returned from ListResponse.

FirstOrder is the first resource in the List request.

SecondOrder is the second resource in the List request.