StructureMap: IRepository and Test Data Injection
I Love StructureMap! It’s wonderful. What a way to compose your code together easily, precisely, and consolidatedly (!!). When I put a sentence like that together, I wonder if I even know what I’m talking about. The problem with StructureMap, IoC, and dependency injection really seems to be that the jargon for the patterns is so manifestly true that once you learn what the hell you are doing, you are completely unable to stop talking about it in shorthand. And that shorthand makes absolutely no sense to someone who hasn’t absorbed the patterns. Keep plugging, people. Once you do it, you’ll get it. Then you’ll be there and not be able to explain to other people why you’re so right. It’s like being Tom Cruise and needing to explain scientology.
Anyways.
I learned two things today. The first is how to hook all of my concrete generic repository types together with their interfaces. I had been adding a line of configuration for each repository. Now my test code looks like this:
ForRequestedType(typeof(IRepository<>)).TheDefaultIsConcreteType(typeof(ListRepository<>));
And my production code:
ForRequestedType(typeof(IRepository<>)).TheDefaultIsConcreteType(typeof(LlblRepository<>));
That’s easy!
The other thing I learned is that I can happily and easily inject data into my object registry for testing purposes. I have an in-memory repository implementation built. All it needs is data.
public class MemoryDataSource
{
private Dictionary<Type, IQueryable> data;
public MemoryDataSource(Dictionary<Type, IQueryable>
data)
{
this.data = data;
}
public IQueryable GetQueryable(Type type)
{
return this.data[type];
}
}
public class ListRepository<T>
: IRepository<T>
{
private MemoryDataSource source;
public ListRepository(MemoryDataSource source)
{
this.source = source;
}
public IQueryable<T> GetSource()
{
return ((IQueryable<T>)source.GetQueryable(typeof(T)));
}
public void SaveEntity(T
entity)
{
return;
}
}Now all I need to do is build a Dictionary<> keyed on the entity object type and fill it up with data. Once I’ve done that, I just pass it into the StructureMap registry like this:
ObjectFactory.Inject<Dictionary<Type, IQueryable>>(dataSource);
Now I can have ObjectFactory construct my object under test and it’s got just the data I need it to have.
