Application Start event SpecFlow

Question

I am dealing with a issue where I am trying to instantiate a shared resource in a Selenium SpecFlow project. The resource is a pool of logins (Dictionary<Login, DateTime>).

Constraint 1: The application is not designed to be logged into concurrently with more than on login at a time. That said, many different users can log in at the same time, but the same users should not log in concurrently at the same time. So the items of the dictionary need to be limited to one thread at a time.

Constraint 2: There is no dependency injection on the project, and I am looking for the equivalent of an application state event.

Note 1: I am coming from a MVC ASP.NET background, and would do something like the global.asax App_Start() method.

Note 2: I will be accessing my Dictionary from the Step Definitions to 'reserve' logins, as well as from the hooks to 'release' the logins.

Is there anything like this in Specflow?

Thanks Devin

UPDATE 9/24/2020:

I've worked on this problem some more, and am deciding to go with a Singleton class. The Singleton is not instantiated until it is first called, then will only instantiate a single instance.

UPDATE 9/24/2020 #1:

I found a caveat to using the Singleton pattern, the issues is that our Specflow project is configured for 'Parallel Execution with Memory Isolation', meaning you cannot share state between threads, and this seems like the recommend way according to Specflow. I found this out the hard way, when I found I was getting 25 unique instances of my Dictionary<Login, DateTime>.

That being said, I am not sure if even I did implement a DI framework, that it wouldn't have the same issue.

I am looking to other forms of persistent storage now, likely going to try Azure Storage Tables.

• Ref: Singleton pattern - https://csharpindepth.com/articles/singleton

• Ref: Specflow Parallel Execution with Memory (AppDomain) Isolation - https://docs.specflow.org/projects/specflow/en/latest/Execution/Parallel-Execution.html#parallel-execution-with-memory-appdomain-isolation

Answer 1

In SpecFlow how can I share data between steps/features? appears to be a duplicate, but because of its age and lack of code examples I decided not to mark this question as a duplicate.

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Constraint 2: There is no dependency injection on the project, and I am looking for the equivalent of an application state event.

You say there is no dependency injection, but since you are using SpecFlow you have the BoDi dependency injection framework already. Furthermore, SpecFlow already comes with its own way of sharing data between steps in a thread safe manner: the ScenarioContext object.

You need only declare the ScenarioContext object as a parameter in the step definition constructor (see Context Injection), assign it to a field, then use it in your steps. You can do this in multiple classes to share data (see Sharing Data between Bindings):

[Binding]
public class LoginSteps
{
    private readonly ScenarioContext scenario;

    public LoginSteps(ScenarioContext scenario)
    {
        this.scenario = scenario;
    }

    [Given(@"User is logged in as ""(.*)""")]
    public void GivenUserIsLoggedInAs(string username)
    {
        // log user in
        scenario["LoggedInUser"] = username;
    }
}

[Binding]
public class SomeOtherStepDefinitionFile
{
    private readonly ScenarioContext scenario;

    public SomeOtherStepDefinitionFile(ScenarioContext scenario)
    {
        this.scenario = scenario;
    }

    [When(@"some other step requiring current user")]
    public void WhenSomeOtherStepRequiringCurrentUser()
    {
        var currentUsername = (string)scenario["LoggedInUser"];
    }
}

The ScenarioContext object gets passed around as constructor arguments, and one object is initialized for each test. This makes the ScenarioContext object thread safe, and enables parallel execution of SpecFlow tests, which is what you are really after.