public void SetHeaderKeyValuesShouldAppendToExistingHeaders() { IHeaderDictionary headers = new HeaderDictionary( new Dictionary <string, StringValues>() { { "HeaderName", new StringValues("app=id") } }); HttpHeadersUtilities.SetHeaderKeyValue(headers, "newHeader", "key", "value"); Assert.Equal(2, headers.Count); Assert.Equal("HeaderName", headers.First().Key); Assert.Equal("app=id", headers.First().Value); Assert.Equal("newHeader", headers.Skip(1).First().Key); Assert.Equal("key=value", headers.Skip(1).First().Value); }