Recently had a doubt about how and where to test repository methods.
Let the following situation: I have an interface IRepository
like this:
public interface IRepository<T>
where T: class, IEntity
{
IQueryable<T> Query(Expression<Func<T, bool>> expression);
// ... Omitted
}
And a generic implementation of IRepository
public class Repository<T> : IRepository<T>
where T : class, IEntity
{
public IQueryable<T> Query(Expression<Func<T, bool>> expression)
{
return All().Where(expression).AsQueryable();
}
}
This is an implementation base that can be used by any repository. It contains the basic implementation of my ORM.
Some repositories have specific filters, in which case we will IEmployeeRepository
with a specific filter:
public interface IEmployeeRepository : IRepository<Employee>
{
IQueryable<Employee> GetInactiveEmployees();
}
And the implementation of IEmployeeRepository
:
public class EmployeeRepository : Repository<Employee>, IEmployeeRepository // TODO: I have a dependency with ORM at this point in Repository<Employee>. How to solve? How to test the GetInactiveEmployees method
{
public IQueryable<Employee> GetInactiveEmployees()
{
return Query(p => p.Status != StatusEmployeeEnum.Active || p.StartDate < DateTime.Now);
}
}
Questions
-
Is right to inherit
Repository<Employee>
?
The goal is to reuse code once all implementingIRepository
already been made. IfEmployeeRepository
inherit onlyIEmployeeRepository
, I have to literally copy and paste the code ofRepository<T>
. -
In our example, in
EmployeeRepository : Repository<Employee>
ourRepository
lies in our ORM layer. We have a dependency here with our ORM impossible to perform some unit test. -
How to create a unit test to ensure that the filter
GetInactiveEmployees
return all Employees in which the Status != Active and StartDate < DateTime.Now. I can not create a Fake/Mock ofIEmployeeRepository
because I would be testing? Need to test the actual implementation ofGetInactiveEmployees
.
The complete code can be found on Github
-
This strikes me as a has-a relationship, since as you mention this class is acting as a filter. So rather than inheriting it should have a private
IRepository<Employee>
field that it can receive whenEmployeeRepository
is constructed. -
Having the option to provide an
IRepository<Employee>
would allow you to mock/fake it and separate the testing concerns. -
Yes, you don’t need to create a mock object of the thing you’re testing. You just need to be able to isolate the method’s behaviour by providing ideal objects for the object you are testing to manipulate.