Coming from SpecFlow

SpecFlow (and Reqnroll) bind Gherkin text to C# methods with regular expressions and generate test classes from .feature files. BDTest skips the text layer: the C# chain is the scenario, and the report text comes from attributes or method names, read at compile time by the source generator bundled in BDTest.

Concept map

SpecFlow / Gherkin	BDTest
.feature file	A test class
Feature: with "As a / I want / So that"	[Story(AsA = ..., IWant = ..., SoThat = ...)] on the class
Scenario:	A test method with [ScenarioText("...")]
Given / When / Then / And / But lines	Given(...), When(...), Then(...), .And(...), .But(...)
[Binding] step definitions with regex	Ordinary methods, optionally with [StepText("... {parameterName} ...")]
Step argument transformations	Typed arguments, plus IStepTextStringConverter<T> for display
ScenarioContext / context injection	The per-test Context object
Scenario Outline: + Examples:	ScenarioOutline(...) with typed rows
@tags	[BDTestTag("...")]
[BeforeStep] / [AfterStep] hooks	OnBeforeStep / OnAfterStep or IStepHook registrations on BDTestOptions.StepHooks
[BeforeScenario] / [AfterScenario]	Your framework's per-test hooks, such as TUnit's [Before(HookType.Test)] / [After(HookType.Test)]
@ignore	Your framework's ignore attribute, or a skip rule
ScenarioContext.Pending()	Throw NotImplementedException: the step becomes NotImplemented
LivingDoc / reports	The HTML report or report server

Example

Feature: Withdrawals
  As an account holder
  I want to withdraw money
  So that I can use my savings

  Scenario: Withdrawing money reduces the balance
    Given I have an account with a balance of 100
    When I withdraw 25
    Then the account balance is 75

becomes:

Illustrative fragment

[Story(AsAn = "account holder", IWant = "to withdraw money", SoThat = "I can use my savings")]
public class WithdrawalTests : TUnitBDTestBase<AccountContext>
{
    private AccountSteps Account => new(Context);

    [Test]
    [ScenarioText("Withdrawing money reduces the balance")]
    public async Task WithdrawingMoneyReducesTheBalance()
    {
        await Given(() => Account.CreateAnAccount(100m))
            .When(() => Account.Withdraw(25m))
            .Then(() => Account.TheBalanceIs(75m));
    }
}

The step definitions become methods with [StepText]:

Illustrative fragment

public class AccountSteps(AccountContext context)
{
    [StepText("I have an account with a balance of {balance}")]
    public void CreateAnAccount(decimal balance) => context.Balance = balance;

    [StepText("I withdraw {amount}")]
    public void Withdraw(decimal amount) => context.Balance -= amount;

    [StepText("the account balance is {expected}")]
    public async Task TheBalanceIs(decimal expected) => await Assert.That(context.Balance).IsEqualTo(expected);
}

Migration tips

• Migrate one feature at a time. BDTest and SpecFlow tests can live in the same solution, in separate projects.
• Turn each regex step definition into a method with a readable name. Often the method name alone produces good step text, so [StepText] is optional.
• Move ScenarioContext keys into properties on a typed context class.
• Replace table arguments with typed objects or collections.
• Use .When(...).And(...).Then(...) for scenarios with multiple actions. And and But keep the current phase.