C++ Builder Pattern Based on Configuration - c++

I found this useful gist that introduced me into Builder Pattern Design.
How would one implement this code to build a "Car" object with required and optional parameters based on configurations without writing dedicated builders?
Scenario 1
Build a car with 3 wheels, no body and no engine.
Scenario 2
Build a car with 2 wheels, with a body and an engine.
Scenario 3
Build a car with 1 wheel, no body and no engine.
Scenrion N
Some other random combination.
And let's imagine the "Car" object requires at least one wheel to be built.
I have stumbled upon a blog post that mentions a state machine approach but it still seems a bit messy to me.
The post: https://blog.jayway.com/2012/02/07/builder-pattern-with-a-twist/

what about following:
inject Configuration Context as an argument into method getCar() in class Director then build appropriate Car object there
comments in gist are self explanatory:
/* Builder is responsible for constructing the smaller parts /
/ Director is responsible for the whole process */

Related

Best way to setup test cases that are "late" in a process

Best way of handling many test cases needing to navigate to a particular place before they run their asserts? For example a process has 5 steps and a test case needs to test a part of step 5, how can I set it up? Call the test case methods of the previous steps inside this test case, and do that for all test cases that test step 5?
Similarly, if a test case goes deep into the website - through many pages - should that navigation be re-written for every test case, or just call some test that already does that?
Any tips on this situations?
Best way of handling many test cases needing to navigate to a particular place before they run their asserts? For example a process has 5 steps and a test case needs to test a part
of step 5, how can I set it up?
I would create a Transporter class / pattern that the test case can call to get to that state. That will make the navigation code reusable to other tests and not make the test too big/complicated. You can also use the setUp() methods in your xUnit testing frameworks which will be called before each test and place the navigator code there, if you need to use it for other tests.
Similarly, if a test case goes deep into the website - through many
pages - should that navigation be re-written for every test case, or
just call some test that already does that?
I would extract that code into a helper class called Transporter and have the tests call it to easily navigate to the deep page in one method call.
I wrote about this and other test design patterns in a conference paper at the Pacific Northwest Software Quality Conference. Look for the Transporter pattern in that paper.
Here's an example using a Transporter class where you have to login and navigate to the checkout page:
public class Transporter {
public static void login() {
//App specific code to navigate to login screen and login to the application
}
public static void gotoCheckout() {
//App specific code to navigate to the checkout page
}
}
Now your tests can just call this Transporter class to do the navigation for them.
If you are using BDD, such as JBehave (not sure if Cucumber has the same feature) where you have the Given, When, Then story (feature) structure in Gherkin syntax, you can actually use "GivenStories" feature which are like prequel test cases to set you up for your specific test case, exactly as you are describing.
There's nothing wrong, however, when using BDD to simply make multiple step scenarios leading up to the particular test case, i.e. first scenario logs-in, second scenario navigates to certain page, third scenario performs your actual test.
By writing it as a separate story (feature), however, you can re-use those as "GivenStories" in JBehave as a shortcut to get where you need to be without duplicating the steps.

Spree + Overwrite whole code base for modification and addition of new features

Just beginner for Spree Framework
I am trying to bring the whole code base to my local repository, so that I am make relevant changes as per my requirement like addition of different API calls to fill by Product tables.
Just like Devise, we can bring the code base to local code base for modification. In the same manner, I am willing to pull the code base and making changes as per requirement.
Please suggest something so that I can make changes as per my requirement.
I found Solidus as option to full fill my requirement.
Thanks
You can just override/add code as you want using class_eval. Here is example
#app/controllers/spree/admin/images_controller_decorator.rb
Spree::Admin::ImagesController.class_eval do
def index
#images = Spree::Image.all
end
end

What is the controller allowed to assume about what it recieves from a service?

Quick terminology question that's somewhat related to my main question: What is the correct term for a model class and the term for a instance of that class?
I am learning Test Driven Development, and want to make sure I am learning it the right so I can form good habits.
My current project has a SalesmanController, which is pretty much a basic resource controller. Here's my current issue (I can get it working, but I want to make sure its done as "right" as possible)
I have a 'Salesman' model.
The 'Salesman' is mapped as having many 'Sales' using my ORM.
The 'Sales' model is mapped as belongsTo 'Salesman' using my ORM.
I have created a ORMSalesmanRepository which implements the SalesmanRepositoryInterface.
My controller has SalesmanRepositoryInterface passed to it upon construction(constructor dependency injection).
My controller calls the find method on the SalesmanRepositoryInterface implementation it has been given to find the correct salesman.
My view needs information on the salesman and information on all 'Sales' records that belong to him.
The current implementation of SalesmanRepositoryInterface returns an instance of a ORMRecord, and then passes that to the view, which retrieves the sales from the ORMRecord.
My gut tells me this implementation is wrong. The orm record implements Array Access, so it still behaves like an array as far as the view knows.
However, when trying to go back and implement my unit tests I am running into issues mocking my dependencies. (I now know with TDD I'm supposed to make my unit tests and then develop the actual implementation, didn't figure this out till recently).
Salesman = MockedSalesman;
SalesRecords = MockedSalesman->Sales;
Is it poor programming to expect my Salesman to return a ORMObject for the controller to use (for chaining relationships maybe?) or is a controller becoming to 'fat' if I'm allowing it to call more than just basic get methods (using arrayaccess []) on the ORMObject? Should the controller just assume that whatever it gets back is an array (or at least acts like one?)
Also, should it ever come up where something one of my mocked classes returns needs to be mocked again?
Thanks in advance everybody.
What is the correct term for a model class and the term for a instance of that class?
Depends on what you mean with "model classes"? Technically model is a layer, that contains several groups of classes. Most notable ones would be: mappers, services an domain objects. Domain objects as whole are implementation of accumulated knowledge about business requirements, insight from specialists and project goals. This knowledge is referred to as "domain model".
Basically, there is no such thing as "model class". There are classes that are part of model.
What is the controller allowed to assume about what it recieves from a service?
Nothing, because controller should not receive anything from model layer. The responsibility of controller is to alter the state of model layer (and in rare cases - state of current view).
Controller is NOT RESPONSIBLE for:
gather data from model layer,
initializing views
passing data from model layer to views
dealing with authorization checks
The current implementation of SalesmanRepositoryInterface returns an instance of a ORMRecord, and then passes that to the view, which retrieves the sales from the ORMRecord.
It sounds like you are implementing active record pattern. It has very limited use-case, where is is appropriate to use AR - when object mostly consists of getters and setters tht are directly stored in a single table. For anything beyond that active record becomes an anti-pattern because it violates SRP and you loose the ability to test your domain logic without database.
Also, are repository should be returning an instance of domain object and makes sure that you are not retrieving data repeatedly. Repositories are not factories for active record instances.
Is it poor programming to expect my Salesman to return a ORMObject for the controller to use (for chaining relationships maybe?) or is a controller becoming to 'fat' if I'm allowing it to call more than just basic get methods (using arrayaccess []) on the ORMObject?
Yes, it's bad code. Your application logic (one that would usually be contained in services) is leaking in the presentation layer.
At this stage I wouldn't stress too much about your implementation - if you try and write proper tests, you'll quickly find out what works and what doesn't.
The trick is to think hard about what each component is trying to achieve. What is your controller method supposed to do? Most likely it is intended to create a ViewModel of some kind, and then choose which View to render. So there's a few tests right there:
When I call my controller method with given arguments (ShowSalesmanDetail(5))
It should pick the correct View to render ('ShowSalesmanDetail')
It should construct the ViewModel that I expect (A Salesman object with some Sales)
In theory, at this point you don't care how the controller constructs the model, only that it does. In practice though you do need to care, because the controller has dependencies (the big one being the database), which you need to cater for. You've chosen to abstract this with a Repository class that talks to an ORM, but that shouldn't impact the purpose of your tests (though it will definitely alter how you implement those tests).
Ideally the Salesman object in your example would be a regular class, with no dependencies of its own. This way, your repository can construct a Salesman object by populating it from the database/ORM, and your unit tests can also use Salesman objects that you've populated yourself with test data. You shouldn't need to mock your models or data classes.
My personal preference is that you don't take your 'data entities' (what you get back from your ORM) and put them into Views. I would construct a ViewModel class that is tied to one View, and then map from your data entities to your ViewModel. In your example, you might have a Salesman class which represents the data in the database, then a SalesmanModel which represents the information you are displaying on the page (which is usually a subset of what's in the db).
So you might end up with a unit test looking something like this:
public void CallingShowSalesmanShouldReturnAValidModel()
{
ISalesmanRepository repository = A.Fake<ISalesmanRepository>();
SalesmanController controller = new SalesmanController(repository);
const int salesmanId = 5;
Salesman salesman = new Salesman
{
Id = salesmanId,
Name = "Joe Bloggs",
Address = "123 Sesame Street",
Sales = new[]
{
new Sale { OrderId = 123, SaleDate = DateTime.Now.AddMonths(-1) }
}
};
A.CallTo(() => repository.Find(salesmanId)).Returns(salesman);
ViewResult result = controller.ShowSalesman(salesmanId) as ViewResult;
SalesmanModel model = result.Model as SalesmanModel;
Assert.AreEqual(salesman.Id, model.Id);
Assert.AreEqual(salesman.Name, model.Name);
SaleModel saleModel = model.Sales.First();
Assert.AreEqual(salesman.Sales.First().OrderId, saleModel.OrderId);
}
This test is by no means ideal but hopefully gives you an idea of the structure. For reference, the A.Fake<> and A.CallTo() stuff is from FakeItEasy, you could replace that with your mocking framework of choice.
If you were doing proper TDD, you wouldn't have started with the Repository - you'd have written your Controller tests, probably got them passing, and then realised that having all this ORM/DB code in the controller is a bad thing, and refactored it out. The same approach should be taken for the Repository itself and so on down the dependency chain, until you run out of things that you can mock (the ORM layer most likely).

Is it possible to exclude Entity Framework Autogenerated Code from Code Coverage Statistics?

I have seen the [DebuggerNonUserCode] and [ExcludeFromCodeCoverage] attributes in resources and other SO questions about exlcuding code from coverage statistics, and wanted to know if it was possible to automatically add this attribute to the classes in the code generated by the Entity Framework using .NET 4.0.
Also would it need to be class level or could it be on the diagram.Designer.cs level, needing one attribute for all code generated by that diagram?
Since partial classes (which Entity Framework creates) merge attributes, extended functionality in other partial classes are also excluded if the attribute is class level in the template, it will have to be applied at the method level.
The best way that I've found to do this is using T4 (as recommended in #Craig Stuntz's answer) to:
include: using System.Diagnostics.CodeAnalysis; at the top of the file
Then apply [ExcludeFromCodeCoverage] to getters, setters and Factory methods by searching for:
#>get
#>set
Template_FactoryMethodComment
and placing them in the appropriate place.
This was made a lot easier using Tangible's T4 editor Extension for VS.
This is my first attempt and it seems to work, "your milage may vary", so complete a test run to make sure everything's working as necessary.

Repository Pattern - POCOs or IQueryable?

I'm new to the Repository Pattern and after doing a lot of reading on the web I have a rough understanding of what is going on, but there seems to be a conflict of ideas.
One is what the IRepository should return.
I would like to deal in ONLY Pocos so I would have an IRepository implementation for every aggregate root, like so:
public class OrangeRepository: IOrangeRepository
{
public Orange GetOrange(IOrangeCriteria criteria);
}
where IOrangeCriteria takes a number of arguments specific to finding an Orange.
The other thing I have is a number of data back-ends - this is why I got into this pattern in the first place. I imagine I will have an implementation for each, e.g
OrangeRepositoryOracle, OrangeRepositorySQL, OrangeRepositoryMock etc
I would like to keep it open so that I could use EF or NHibernate - again if my IOrangeRepository deals in POCOs then I would encapsulate this within the Repository itself, by implementing a OrangeRepositoryNHibernate etc.
Am I on the right lines?
Thanks
EDIT: Thanks for the feedback, I don't have anyone else to bounce these ideas off at the moment so it is appreciated!
Yes, your version is the safest / most compatible one. You can still use it with about any resources, not only data access ones, but with web services, files, whatever.
Note that with the IQueryable version you still get to work based on your POCOs classes, but you are tied to the IQueryable. Also consider that you could be having code that uses the IQueryable and then turns out it you hit a case where one of the repository's ORM doesn't handle it well.
I use the same pattern as you do. I like it a lot. You can get your data from any resources.
But the advantage of using IQuerable is that you do not have to code your own criteria API like the OrangeCriteria.
When NHibernate gets full Linq support then I may switch to the IQueryable.
Then you get
public class OrangeRepository: IOrangeRepository {
public IQueryable<Orange> GetOranges();
}