Tuesday, June 30, 2015

Unit Testing in Sitecore

Unit testing seems to be one of those topics that everyone generally agrees is a Good Idea, but when no one is looking it becomes fantastically easy to justify to oneself why for this project at this particular time it's ok to forgo unit tests.

My purpose here isn't to convince (guilt) you into doing unit tests. Rather, I'd like to demonstrate that actually implementing them can be trivially easy. Now, of course, anyone can write a unit test that is easy but does it add value? Well, that'll depend upon you, of course. My advice is target the hot spots in your code first and anytime you encounter a bug write a unit test that validates the bug is resolved. Aiming for 100% code coverage is admirable but don't let the perfect be the enemy of the good. Ok—enough preaching philosophizing!

Tools

First a word about tools. I favor Glass (version 3 for the purpose of this blog post) as my Sitecore ORM; this will have some ramifications for unit tests. As far as a unit testing framework, I have settled upon xUnit. Is this terribly important? Not especially. NUnit is quite popular and powerful. The designers of NUnit actually wrote xUnit. You can view their reasons for doing so here. Regardless of which framework you select, most of what I document here will still apply, the main difference is the syntax. For mocking, I have come to really like Sitecore.FakeDb. It's an amazing product. Add a NuGet package to your project and you suddenly have to power to run all of Sitecore's API without the need of a website. There are other Sitecore mocking tools out there, but I highly recommend this one. Finally, for a bit of syntactic sugar I suggest Fluent Assertions. Again, simply add the NuGet to your project and your assertion statements will read very nearly like English.

Some Lessons Learned

  • I don't need FakeDb for data mocking so long as I am working solely with Glass object. Since every Glass-mapped class is an implemenation of an interface, my mock test data can also simply implement that interface.
  • FakeDb is convenient, nonetheless, because it allows Glass's CreateFakeItem method to 'just work' without having to go the extra length of providing a testing database along with hand-(re)creating all of the config settings necessary to connect Sitecore's API layer to a data provider. This means that for very simple API calls you could avoid mocking with FakeDb and do it all through Glass. In practice, however, I find FakeDb to be so fast as to leave me wonder if there is any advantage to this.'
  • I can (if I want) cast from a FakeDb item to a Glass object. Nathanael Mann warns against this practice for performance reasons and because it blurs the line between unit testing and integration testing. In fairness, I am over-simplifying his thesis a bit, nonetheless, for me, the raw convenience of being able easily to mock Sitecore data is simply too powerful to ignore. As far as performance goes, once Glass's context has been created (~800ms hit) unit tests involving Glass run in less than 10ms even when casting. 10 seconds per 1000 tests? I can accept that.

Everybody Loves an Example


namespace MyPOCO.Tests.Data.Domain
{
    public class My_POCO_Tests
    {
        public class DoesQueryStringMatchMethod
        {

            public static DbTemplate GetMyPOCOTemplate()
            {
                return new DbTemplate(IMy_POCOConstants.TemplateName, IMy_POCOConstants.TemplateId)
                {
                    new DbField(IMy_POCOConstants.Query_String_Value_To_MatchFieldName, 
                        IMy_POCOConstants.Query_String_Value_To_MatchFieldId)
                };
            }
             
            [Fact]
            public void RequestedUrlHasUpperCaseValues()
            {
                //arrange
                string requestedUrl = "http://www.google.com?foo=bar&color=RED";
                GlassMapperContext.CreateContext();
                using (var db = new Db
                {
                    FakeDbHelper.GetMyPOCOTemplate(),
                    new DbItem("test", ID.NewID, IMy_POCOConstants.TemplateId)
                    {
                        {IMy_POCOConstants.Query_String_Value_To_MatchFieldName, requestedUrl}
                    }
                })
                {
                    global::Sitecore.Data.Items.Item home = db.GetItem("/sitecore/content/test");
                    My_POCO poco = home.GlassCast<My_POCO>();

                    //act
                    bool result = poco.DoesQueryStringMatch(requestedUrl);

                    //assert
                    result.Should().BeTrue();
                }
            }
        }
    }
}

So, what does this code demonstrate? It shows a Glass-mapped object that has a method I wish to unit test. The method is named DoesQueryStringMatch. Presumably, the method compares the requested URL against a field value and returns a boolean. Of course, a more realistic and more useful test would be against a method that had a more complicated job to do, but for purposes of illustrating the technique we'll stick with a contrived example.

 I could have mocked my Glass object without the need for FakeDb, and I do need to create my Glass context (that's the GlassMapperContext.CreateContext() method call.) Once that work is done, however, I am free and clear for all further unit tests where I may have need to test against Sitecore items—example: an action for the rules engine. I leverage the fact that Glass maintains constants about my template and its fields. Necessary? No, but very useful if I have to create an item with a complicated structure. Creating the Glass context is simple enough. I just replicate the code called in the Start() method of GlassMapperSc.cs.


3 comments:

  1. Hi there! Good to see blog posts about FakeDb ;)

    I like the list of tools you're using: xUnit, FluentAssertions. I use the same tools + AutoFixture which allows to decrease the size of my tests.
    In case of FakeDb, instead of creating a `db` instance via the `using(new Db())` statement, you may just rely on the AutoFixture! There is no wide support in the FakeDb so far, but there is a couple of code snippets that might be interesting: https://github.com/sergeyshushlyapin/Sitecore.FakeDb/wiki/Autofixture-Samples

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    Replies
    1. Hi, Sergey. :) Honored to see you here in my comments! I've actually looked at the AutoFixture project, and it's quite intriguing. I haven't applied it yet to any production code, but I promise to blog about it when I do so.

      Delete
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