public async Task Send_WithUrlAndDefaultParameters_ShouldBuildCorrectUrl() { // Arrange var httpClient = A.Fake <IHttpClient>(); var url = "test/itemName/123"; var defaultParams = new NameValueCollection { { "APIKey", "keyvalue" } }; var expectedUrl = "/test/itemName/123?APIKey=keyvalue"; A.CallTo( () => httpClient.SendAsync( A <HttpRequestMessage> .Ignored)) .Returns(_basicResponse); A.CallTo( () => httpClient.Client) .Returns(_basicClient); var requester = new WebRequester(httpClient, defaultParams); // Act var request = new HttpRequestMessage(HttpMethod.Get, url); await requester.SendMessageAsync(request); // Assert A.CallTo( () => httpClient.SendAsync( A <HttpRequestMessage> .That.Matches(req => req.RequestUri.ToString().Equals(expectedUrl))) ).MustHaveHappened(); }