Nunit tests on Response.Cache.VaryByHeader - asp.net

Question

I am doing some Unit testing with NUnit and NSubstitute on a function that uses HttpResponse, I know you can't mock these objects so I have created interfaces to represent them and some of there properties.
I'm having trouble understanding how to create an interface for Response.Cache.VaryByHeader
// This is my HttpResponse interface
public interface IHttpResponse
{
Stream Filter { get ; set; }
IHttpCachePolicy Cache { get; set; }
void AppendHeader(string name, string value);
}
// concrete httresponse
public class HttpResponseProxy : IHttpResponse
{
private HttpResponse _httpResponse;
public Stream Filter {
get {
return _httpResponse.Filter ?? new MemoryStream();
}
set { _httpResponse.Filter = value; }
}
public IHttpCachePolicy Cache
{
get { return new HttpCachePolicyProxy(_httpResponse.Cache); }
set { }
}
public HttpResponseProxy(HttpResponse httpResponse)
{
if (httpResponse == null)
{
throw new ArgumentNullException("httpResponse");
}
_httpResponse = httpResponse;
_httpResponse.Filter = httpResponse.Filter;
}
public void AppendHeader(string name, string value)
{
_httpResponse.AppendHeader(name, value);
}
}
// HttpCachePolicy interface
public interface IHttpCachePolicy
{
IHttpCacheVaryByHeaders VaryByHeaders { get; set; }
}
// concrete HttpCachePolicy
public class HttpCachePolicyProxy : IHttpCachePolicy
{
private HttpCachePolicy _httpCachePolicy;
public HttpCachePolicyProxy(HttpCachePolicy httpCachePolicy)
{
_httpCachePolicy = httpCachePolicy;
}
public IHttpCacheVaryByHeaders VaryByHeaders
{
get { return new HttpCacheVaryByHeadersProxy(_httpCachePolicy.VaryByHeaders as HttpCacheVaryByHeaders); }
set { }
}
}
public interface IHttpCacheVaryByHeaders
{
IHttpCacheVaryByHeaders HttpCacheVaryByHeaders { get; set; }
}
public class HttpCacheVaryByHeadersProxy : IHttpCacheVaryByHeaders
{
private HttpCacheVaryByHeaders _httpCacheVaryByHeaders;
public HttpCacheVaryByHeadersProxy(HttpCacheVaryByHeaders httpCacheVaryByHeaders)
{
_httpCacheVaryByHeaders = httpCacheVaryByHeaders;
}
public IHttpCacheVaryByHeaders HttpCacheVaryByHeaders
{
get { return new HttpCacheVaryByHeadersProxy(_httpCacheVaryByHeaders); }
set { }
}
}
This is the function i am actually testing:
public static void CompressPage(IHttpRequestGetCompressionMode getCompressionMode, IHttpResponse httpResponse)
{
string supportedCompression = getCompressionMode.GetClientSupportedCompressionMode();
if (supportedCompression != HttpHeaderValues.NoCompression)
{
switch (supportedCompression)
{
case HttpHeaderValues.DeflateCompression:
httpResponse.Filter = new DeflateStream(httpResponse.Filter, CompressionMode.Compress);
break;
case HttpHeaderValues.GZipCompression:
httpResponse.Filter = new GZipStream(httpResponse.Filter, CompressionMode.Compress);
break;
}
httpResponse.AppendHeader(HttpHeaderValues.ContentEncodingHeader, supportedCompression);
// this line is where i have the problem
httpResponse.Cache.VaryByHeaders[HttpHeaderValues.AcceptEncodingHeader] = true;
}
}
I'm getting "cannot apply index to an expression of type IHttpCacheVaryByHeaders" errors.
I have the interface for the response and cache but how do I represent VaryByHeaders in an interface and then use it in a concrete class?

Answer 1

The error seems to suggest that IHttpCacheVaryByHeaders does not have an indexer declared (e.g. bool this[string header] { get; set; }), but rather than implementing these wrappers yourself, try the HttpResponseWrapper and other System.Web.Abstractions. This will should make testing this stuff a lot easier. :)