Generics in Setup

[AngeloHulshout]

I am migrating from SpecFlow to Reqnroll - understandably in a relative hurry. I chose to bypass the SpecFlow compatibiliy assembly and just rename Techtalk.Specflow to Reqnroll. That surprisingly made everything build without problems right away.
However, I have some generics in the setup stage, and when running my tests I am confronted with "Reqnroll.BindingException : Binding error(s) found: Binding types cannot be generic: "

That is something we can refactor around, but it brings two questions:

1. Would this work with the Specflow compatibility assembly? No need to answer, I'll give it a try.
2. Why are generics not supported in reqnroll during setup? Is this a temporary limitation or a decisison towards the future?

And apart from that: thanks for the fork, this is going to save us a lot of trouble now that SpecFlow will be gone in 3 days.

[olegKoshmeliuk]

Hi,

Looks like you trying to use open generics in bindings.
Since open generic types can't created without type parameters that's why you getting an error.
Maybe you by mistake put [Binding] on abstract generic class?

Ideally add example proejct to get an idea where you using open generic types in Specflow or Reqnroll.

[Binding]  // this will throw you error
public class StepsBase<T> { }

[Binding]
public class UserSteps: StepsBase<User> { }

code related to your error:

Reqnroll/Reqnroll/Bindings/Discovery/BindingSourceProcessor.cs

Line 311 in 642c8bc

result += BindingValidationResult.Error($"Binding types cannot be generic: {bindingSourceType}");

[AngeloHulshout]

Thank you for that link. This is definitely related, but I need to do some refactoring as I said. Still don't understand why this does not work with reqnroll while it did with SpecFlow, but we'll sort that out. In line with your example, what I have is:

[Binding]
public class TestBase
...

abstract class TestBase : TestBase where TSetupService : class, ISetupService
....

Binding types cannot be generic: app.specs.TestBase`1[TSetupService]

[olegKoshmeliuk]

Can you show example project with valid code? (just create specflow/reqnroll empty project) and edit CalculatorStepDefinitions.
Even in specflow startup project don't allow generic types for Bindings. Tried step bindings and BeforeScenario hooks

BTW original specflow have this check too.
https://github.com/endjin/SpecFlow/blob/d93324577d603a7096d264b4fb60a8e49a07919c/TechTalk.SpecFlow/Bindings/Discovery/BindingSourceProcessor.cs#L243

[AngeloHulshout]

I believe you, Oleg, but ... my original project compiled and ran fine until klast week with SpecFlow 3.9 - after switching to reqnroll this problem started occurring.

My previous post didn't show correclty, for some reason the discussion software removed the 'generic' indication.

This is what I had:

[Binding]
public class TestBase {
...
}

abstract class TestBase<TSetupService> : TestBase where TSetupService : class, ISetupService
{
...
}


class PTest : TestBase<IPSetup>
{
...
}

class SingleTest : PTest
{
...
}

I fixed the problem last night by doing this - moving the Binding to the concrete test. No idea how this always worked, we've been using it like above for over a year.

public class TestBase {
...
}

abstract class TestBase<TSetupService> : TestBase where TSetupService : class, ISetupService
{
...
}


class PTest : TestBase<IPSetup>
{
...
}

[Binding]
class SingleTest : PTest
{
...
}

[olegKoshmeliuk]

It's new behaviour of reqnroll (maybe it was planned for specflow 4.0). Reqnroll validates all bindings inside registry and in case of invalid fails early.
Binding attribute is applied to base and all child classes.
For you case you need to move Binding attribute from base to child classes that will be created by Reqnroll during steps.

[AngeloHulshout]

That's basically what I did. Thanks for guiding the thought process!