AutoMapper getting maps mixed up when running large number of tests? - unity-container

Question

I currently have a solution with about 1000 unit/integration tests using MSTest runner. The problem Im experiencing with AutoMapper is that when I have VS run all tests in the solution, I'll randomly get a few unit tests fail due to the following automapper exception:
AutoMapper.AutoMapperMappingException:
Mapping types:
String -> String
System.String -> System.String
Destination path:
CatalogResource.CultureCode
Source value:
en-US ---> System.InvalidCastException: Unable to cast object of type 'Model.Catalog' to type 'Model.CatalogResource'.
In the code I dont have a Catalog to CatalogResource map nor am I trying to map them to each other. This type of exception doesnt happen in PROD, doesnt happen for the integration tests, doesnt happen every time I run the tests and when it does happen, it is always different tests that fail. Also, if I run only the tests that just failed, they always pass. I have a hard time consistently reproducing this locally but it happens more frequently on the build server, which is a pain because it prevents the build from getting automatically promoted to the next environment.
I've also tried adding this to the tests but it has not solved the problem:
[ClassInitialize]
public static void ClassInitialize(TestContext context)
{
Mapper.Reset();
}
Any ideas? We've had 4 different people take a stab at this to no avail so Im resorting to you great folks for help now.
Thanks!
EDIT:
I currently initialize the configuration using a static class that gets called inside a static constructor for the service. I.E.
static MyService()
{
AutoMapperBootstrapper.Initialize();
}
...
internal static class AutoMapperBootstrapper
{
public static void Initialize()
{
ConfigureMappings();
#if DEBUG
Mapper.AssertConfigurationIsValid();
#endif
}
}
EDIT #2:
While doing some more tinkering today, I notice that these random failures happen only for <IDataReader, something else> maps. For example:
Mapper.CreateMap<IDataReader, Catalog>()
.ForMember(m => m.CatalogID, opt => opt.MapFrom(src => src["CatalogID"]))
.ForMember(m => m.Title, opt => opt.MapFrom(src => src["Title"]))
.ForMember(m => m.DateCreatedUTC, opt => opt.MapFrom(src => src["DateCreatedUTC"]))
.ForMember(m => m.DateModifiedUTC, opt => opt.MapFrom(src => src["DateModifiedUTC"]))
...
Not sure what to make of it yet but it seemed relevant.

Answer 1

I presume you call AutoMapperBootstrapper.Initialize from your unit tests, and the ONLY location you have the mapping configuration is in ConfigureMappings? I can't explain your issue, but you obviously have some leakage between your unit tests somewhere. I have a similar setup, and this is what I do...
My initialisation code is
public static class MappingConfiguration
{
public static void RegisterMappings()
{
Mapper.Initialize(x =>
{
x.AddProfile<MapperProfileOne>();
x.AddProfile<MapperProfileTwo>();
});
}
}
This is only ever called by the application (I dont bother testing the RegisterMappings method as it only has the single Initialize call and I trust that AutoMapper works. My unit tests (to test my mapping configuration) are as follows:
[Test]
public void Initialise_ProfileOne_GeneratesNoErrors()
{
Mapper.Initialize(x => x.AddProfile<MapperProfileOne>());
Mapper.AssertConfigurationIsValid();
}
[Test]
public void Initialise_ProfileTwo_GeneratesNoErrors()
{
Mapper.Initialize(x => x.AddProfile<MapperProfileTwo>());
Mapper.AssertConfigurationIsValid();
}
An example of a profile is:
public class MapperProfileOne : Profile
{
protected override void Configure()
{
Mapper.CreateMap<Source, Destination>();
}
}
I'm wondering that if you're calling the AutoMapperBootstrapper method from your unit tests that its somehow getting confused (there's not enough detail in the question to determine this for certain). I don't think it should, but hopefully there's at least something in the code above that might magically fix the issue for you.