specflow-testing

Overview

SpecFlow is the legacy .NET BDD framework; Reqnroll forked from it in 2023 as its actively-maintained successor (reqnroll-home (opens in new window)). This skill supports existing SpecFlow projects - for new .NET BDD work use reqnroll-testing (API-compatible).

When to use

• An existing project uses SpecFlow and the team isn't ready to migrate.
• Documentation maintenance for a deprecated codebase.

If starting a new .NET BDD project: stop. Use Reqnroll.

Step 1 - Install (legacy)

<PackageReference Include="SpecFlow" Version="3.9.74" />
<PackageReference Include="SpecFlow.xUnit" Version="3.9.74" />
<PackageReference Include="SpecFlow.Tools.MsBuild.Generation" Version="3.9.74" />

Step 2 - Author a Feature

Same Gherkin as Reqnroll / Cucumber:

Feature: Apply promo code at checkout

  Scenario: Apply valid promo
    Given a logged-in user
    When I enter "WELCOME10" in the promo input
    Then the subtotal updates to $22.49

Step 3 - Step bindings

using TechTalk.SpecFlow;
using Xunit;

[Binding]
public class CartSteps
{
    [Given("a logged-in user")]
    public void GivenLoggedInUser() { /* ... */ }

    [When(@"I enter ""([^""]*)"" in the promo input")]
    public void WhenIEnter(string code) { /* ... */ }

    [Then(@"the subtotal updates to \$(\d+\.\d+)")]
    public void ThenSubtotalUpdates(decimal expected) { /* ... */ }
}

Compare to Reqnroll: using TechTalk.SpecFlow → using Reqnroll. Decorators identical.

Step 4 - Migrate to Reqnroll

Per reqnroll-home (opens in new window): "Compatible with SpecFlow, allowing quick migration of existing projects."

# 1. Remove SpecFlow packages
dotnet remove package SpecFlow
dotnet remove package SpecFlow.xUnit
dotnet remove package SpecFlow.Tools.MsBuild.Generation

# 2. Add Reqnroll equivalents
dotnet add package Reqnroll.xUnit
dotnet add package Reqnroll.Tools.MsBuild.Generation

// 3. Find/replace in code:
//   using TechTalk.SpecFlow → using Reqnroll
//   TechTalk.SpecFlow → Reqnroll

# 4. Run tests; fix any breakages
dotnet test

Most projects migrate in <1 day. The migration is mostly mechanical.

Step 5 - Run

dotnet test
dotnet test --filter "Category=critical"

Same as Reqnroll. The runner is the .NET test framework (xUnit / NUnit / MsTest).

Anti-patterns

Limitations

• Maintenance status. SpecFlow gets bug fixes occasionally; not new features.
• .NET version compatibility. Newer .NET versions land on Reqnroll first.
• IDE plugin updates. SpecFlow plugins for VS / Rider lag behind Reqnroll's.

References

• reqnroll-home (opens in new window) - Reqnroll's own description of itself as "a reboot of the SpecFlow project."
• reqnroll-testing - the recommended skill for new .NET BDD projects.
• cucumber-testing, behave-testing - non-.NET alternatives if rewriting.