Add DI container support for contextual runners

[Suremaker]

Progress

• Feature is implemented,
• Ensured backward-compatibility,
• Ensured good debugging experience.

Description

At this moment it is possible to specify Runner.WithContext<MyContext>() to use contextful runner with context having parameterless constructor. If context has dependencies, it has to be manually instantiated with code like Runner.WithContext(new MyContext(dependency)), and all dependencies has to be resolved manually in code. Finally, the contexts implementing IDisposable interfaces are not disposed after usage.

Initial Idea

• The ˋRunner.WithContext()ˋ should be extended to allow instantiating types with any constructor, using DI container to instantiate the context.
• The DI container should have sane defaults, such as:
  • working without any 3rd-party DI container integrations,
  • resolving dependencies to the widest constructor, without need of explicit registrations,
  • instantiate all types per test,
• The DI container should be configurable with LightBddConfiguration, allowing to:
  • choose a 3rd-party implementation if desired (like Autofac),
  • configure choosen implementation,
• The default DI container implementation should allow to:
  • customize registration of type (custom instantiation with ability to resolve dependency),
  • specify if instance is created per test or shared (optional requirement),
• The runner should be updated to control lifespan of the contexts (dispose if needed)

Story definition

After spike, I have decided to add DI container support to LightBDD with focus on supporting proper, mature DIs but also provide a very basic DI in LightBDD itself.

Features:

• LightBDDConfiguration.DependencyContainerConfiguration() configuration allowing to specify DI container type and configure it,
• LightBDD.Autofac project offering integration with Autofac,
• Basic DI container implementation (enabled by default), supporting:
  • container scoping,
  • instance registration,
  • constructor injections,
  • resource disposals,
• Modify WithContext<TContext>() extension methods to use DI containers and lifting where TContext: new() constraint,
• Add StepExecution.Current.GetScenarioDependencyResolver() extensions to allow retrieving DI resolver during scenario execution,
• Add ResourcePool<T> type for handling resource pools (DI friendly),
• Expose DI containers for scenario/step decorators.

[aidapsibr]

Hey, you might want to check out SpecFlows BoDi container for a default integrated DI container. I am using it in psibr/REstate successfully with external DI support. It is pretty limited, but also easy to modify as I did to support IEnumerable resolutions.

[Suremaker]

Hello @psibernetic . I have just recently came to this ticket to think how to implement it.
Thanks for the hint - I have took a look at the BoDi implementation, however decided to build some abstractions in LightBDD itself to support container scoping (for contextual scenarios and steps) and integration with other DI containers.

I have got a basic DI working which will be shipped with LightBDD 2.4.0, and added LightBDD.Autofac project with sample integration with Autofac. Hopefully, over the time there will be more integrations with other people favourite DIs.

There is still a lot of docs and samples to be written before shipping 2.4.0, but it should appear soon :)

[aidapsibr]

Very good sir, looking forward to it.

[Suremaker]

The feature has been implemented on develop branch and will be released with LightBDD 2.4.0