Mocking HttpContext with JustMock
- by mehfuzh
In post , i will show a test code that will mock the various elements needed to complete a HTTP page request and assert the expected page cycle steps. To begin, i have a simple enumeration that has my predefined page steps: public enum PageStep { PreInit, Load, PreRender, UnLoad } Once doing so, i first created the page object [not mocking]. Page page = new Page(); Here, our target is to fire up the page process though ProcessRequest call, now if we take a look inside method though reflector, we will find calls stack like : ProcessRequest –> ProcessRequestWithNoAssert –> SetInstrinsics –> Finallly ProcessRequest. Inside SetIntrinsics , where it requires calls from HttpRequest, HttpResponse and HttpBrowserCababilities. With this , we can easily know what are classes / calls we need to mock in order to get though the expected call. Accordingly, for HttpBrowserCapabilities our required test code will look like: Mock.Arrange(() => browser.PreferredRenderingMime).Returns("text/html"); Mock.Arrange(() => browser.PreferredResponseEncoding).Returns("UTF-8"); Mock.Arrange(() => browser.PreferredRequestEncoding).Returns("UTF-8"); Now, HttpBrowserCapabilities is get though [Instance]HttpRequest.Browser. Therefore, we create the HttpRequest mock: var request = Mock.Create<HttpRequest>(); Then , add the required get call : Mock.Arrange(() => request.Browser).Returns(browser); As, [instance]Browser.PerferrredResponseEncoding and [instance]Browser.PreferredResponseEncoding are also set to the request object and to make that they are set properly, we can add the following lines as well [not required though]. bool requestContentEncodingSet = false; Mock.ArrangeSet(() => request.ContentEncoding = Encoding.GetEncoding("UTF-8")).DoInstead(() => requestContentEncodingSet = true); Similarly, for response we can write: var response = Mock.Create<HttpResponse>(); bool responseContentEncodingSet = false; Mock.ArrangeSet(() => response.ContentEncoding = Encoding.GetEncoding("UTF-8")).DoInstead(() => responseContentEncodingSet = true); Finally , I created a mock of HttpContext and set the Request and Response properties that will returns the mocked version. var context = Mock.Create<HttpContext>(); Mock.Arrange(() => context.Request).Returns(request); Mock.Arrange(() => context.Response).Returns(response); As, Page internally calls RenderControl method , we just need to replace that with our one and optionally we can check if invoked properly: bool rendered = false; Mock.Arrange(() => page.RenderControl(Arg.Any<HtmlTextWriter>())).DoInstead(() => rendered = true); That’s it, the rest of the code is simple, where i asserted the page cycle with the PageSteps that i defined earlier: var pageSteps = new Queue<PageStep>(); page.PreInit += delegate { pageSteps.Enqueue(PageStep.PreInit); }; page.Load += delegate { pageSteps.Enqueue(PageStep.Load); }; page.PreRender += delegate { pageSteps.Enqueue(PageStep.PreRender); }; page.Unload += delegate { pageSteps.Enqueue(PageStep.UnLoad); }; page.ProcessRequest(context); Assert.True(requestContentEncodingSet); Assert.True(responseContentEncodingSet); Assert.True(rendered); Assert.Equal(pageSteps.Dequeue(), PageStep.PreInit); Assert.Equal(pageSteps.Dequeue(), PageStep.Load); Assert.Equal(pageSteps.Dequeue(), PageStep.PreRender); Assert.Equal(pageSteps.Dequeue(), PageStep.UnLoad); Mock.Assert(request); Mock.Assert(response); You can get the test class shown in this post here to give a try by yourself with of course JustMock. Enjoy!!
