Why does adding a constructor fail this MSpec test with System.InvalidOperationException? - castle-windsor

Question

I have this first version of a class
public class GenerateAuthorisationWorkflows : IGenerateAuthorisationWorkflows
{
public IList<Guid> FromDtaObjects(IList<DtaObject> dtaObjects, Employee requestingEmployee)
{
foreach (var dtaObject in dtaObjects) { }
return new List<Guid>();
}
public IList<Guid> FromDtaObjects()
{
return new List<Guid>();
}
}
And the MSpec tests for it
public abstract class specification_for_generate_workflows : Specification<GenerateAuthorisationWorkflows>
{
protected static IWorkflowService workflowService;
Establish context = () => { workflowService = DependencyOf<IWorkflowService>(); };
}
[Subject(typeof(GenerateAuthorisationWorkflows))]
public class when_generate_workflows_is_called_with_a_dta_object_list_and_an_employee : specification_for_generate_workflows
{
static IList<Guid> result;
static IList<DtaObject> dtaObjects;
static Employee requestingEmployee;
Establish context = () =>
{
var mocks = new MockRepository();
var stubDtaObject1 = mocks.Stub<DtaObject>();
var stubDtaObject2 = mocks.Stub<DtaObject>();
var dtaObjectEnum = new List<DtaObject>{stubDtaObject1,stubDtaObject2}.GetEnumerator();
dtaObjects = mocks.Stub<IList<DtaObject>>();
dtaObjects.Stub(x => x.GetEnumerator()).Return(dtaObjectEnum).WhenCalled(x => x.ReturnValue = dtaObjectEnum);
requestingEmployee = mocks.Stub<Employee>();
mocks.ReplayAll();
};
Because of = () => result = subject.FromDtaObjects(dtaObjects, requestingEmployee);
It should_enumerate_the_dta_objects = () => dtaObjects.received(x=> x.GetEnumerator());
It should_call_workflow_host_helper = () => workflowService.AssertWasCalled(x => x.StartWorkflow());
}
With this configuration, my first test passes and my second test fails, as expected. I added a constructor to the class to inject the IWorkflowService.
public class GenerateAuthorisationWorkflows : IGenerateAuthorisationWorkflows
{
IWorkflowService _workflowService;
GenerateAuthorisationWorkflows(IWorkflowService workflowService)
{
_workflowService = workflowService;
}
public IList<Guid> FromDtaObjects(IList<DtaObject> dtaObjects, Employee requestingEmployee)
{
foreach (var dtaObject in dtaObjects)
{
Guid workflowKey = _workflowService.StartWorkflow();
}
return new List<Guid>();
}
public IList<Guid> FromDtaObjects()
{
return new List<Guid>();
}
}
Now, when I run the tests, they fail at the Because:
System.InvalidOperationException: Sequence contains no elements
at System.Linq.Enumerable.First(IEnumerable`1 source)
at MSpecTests.EmployeeRequestSystem.Tasks.Workflows.when_generate_workflows_is_called_with_a_dta_object_list_and_an_employee.<.ctor>b__4() in GenerateAuthorisationWorkflowsSpecs.cs: line 76
For clarity, line 76 above is:
Because of = () => result = subject.FromDtaObjects(dtaObjects, requestingEmployee);
I've tried tracing the problem but am having no luck. I have tried setting up a constructor that takes no arguments but it raises the same error. I have similar classes with IoC dependencies that work fine using MSpec/Rhino Mocks, where am I going wrong?

Answer 1

Castle Windsor requires a public constructor to instantiate a class. Adding public to the constructor allows correct operation.
public class GenerateAuthorisationWorkflows : IGenerateAuthorisationWorkflows
{
IWorkflowService _workflowService;
public GenerateAuthorisationWorkflows(IWorkflowService workflowService)
{
_workflowService = workflowService;
}
public IList<Guid> FromDtaObjects(IList<DtaObject> dtaObjects, Employee requestingEmployee)
{
foreach (var dtaObject in dtaObjects)
{
Guid workflowKey = _workflowService.StartWorkflow();
}
return new List<Guid>();
}
public IList<Guid> FromDtaObjects()
{
return new List<Guid>();
}
}

Answer 2

Rowan, looks like you answered your own question. It's good practice to explicitly state the access modifiers! By default, C# chooses private. These kinds of errors are easy to miss!
I can also see that your Establish block is too complicated. You're testing the implementation details and not the behavior. For example, you are
stubbing the GetEnumerator call that's implicitly made inside the foreach loop.
asserting that the workflow service was called only once
mixing MSpec automocking and your own local mocks
You're not actually testing that you got a GUID for every object in the input list. If I were you, I'd test the behavior like this...
public class GenerateAuthorisationWorkflows : IGenerateAuthorisationWorkflows
{
private readonly IWorkflowService _service;
public GenerateAuthorisationWorkflows(IWorkflowService service)
{
_service = service;
}
public List<Guid> FromDtaObjects(List<DtaObject> input, Employee requestor)
{
// I assume that the workflow service generates a new key
// per input object. So, let's pretend the call looks like
// this. Also using some LINQ to avoid the foreach or
// building up a local list.
input.Select(x => _service.StartWorkflow(requestor, x)).ToList();
}
}
[Subject(typeof(GenerateAuthorisationWorkflows))]
public class When_generating_authorisation_keys_for_this_input
: Specification<GenerateAuthorisationWorkflows>
{
private static IWorkflowService _service;
private static Employee _requestor = new Employee();
private static List<DtaObject> _input = new List<DtaObject>()
{
new DtaObject(),
new DtaObject(),
};
private static List<Guid> _expected = new List<Guid>()
{
Guid.NewGuid(),
Guid.NewGuid(),
};
private static List<Guid> _actual = new List<Guid>();
Establish context = () =>
{
// LINQ that takes each item from each list in a pair. So
// the service is stubbed to return a specific GUID per
// input DtaObject.
_input.Zip(_expected, (input, output) =>
{
DependencyOf<IWorkflowService>().Stub(x => x.StartWorkflow(_requestor, input)).Return(output);
});
};
Because of = () => _actual = Subject.FromDtaObjects(_input, _requestor);
// This should be an MSpec collection assertion that
// ensures that the contents of the collections are
// equivalent
It should_get_a_unique_key_per_input = _actual.ShouldEqual(_expected);
}