Shift Left using Regression suite

Incorporate the regression suite developed for Quality Control (QC) to ensure Quality Assurance (QA) by embedding it early in the development cycle when creating or adding new features to an existing product.

Introduction

”It works on my machine.” (It doesn’t work in QA. QA found it Thursday. The fix ships Monday. That’s four days of delay, plus you look bad.)

Shift Left is the idea of running tests earlier, when it’s cheaper and faster to fix problems. Instead of waiting for QA to sign off, developers run the regression suite themselves — while developing. The moment you add a feature and break something, you see it in seconds. You fix it immediately. QA gets stable code instead of a pile of surprises.

This isn’t theory. Teams that shift left ship 10× faster because they spend less time in QA triage. Here’s how to wire it up.

Benefits of Shift Left with Early Regression Testing

  1. Early Detection of Issues: By embedding regression tests early, we can identify and address defects as new features are developed, reducing the risk of issues in later stages.
  2. Continuous Quality Assurance: Integrating the regression suite from the start ensures continuous QA, maintaining high standards throughout the development process.
  3. Improved Efficiency: Early testing helps catch and fix issues sooner, leading to more efficient development cycles and faster time-to-market.
  4. Reduced Technical Debt: Proactively addressing defects early minimizes technical debt, resulting in a more stable and maintainable codebase. ##Implementation To successfully implement this approach, we will: • Embed Regression Suite Early: Integrate the existing regression suite into the development process when creating or adding new features. • Automate Testing: Utilize automated testing tools to run regression tests continuously. • Promote Collaboration: Encourage collaboration between developers and testers to ensure alignment on quality standards and requirements.

Approach

  1. You can integrate the QA regression suite as a dependent project (.csproj) within your solution file (.sln).
  2. Modify the configuration .runsetting to point to localhost and add the following code:

To automatically start the Express.js server as a precondition in your C# Startup class, you can use the Process class in .NET to run the Node.js server. This way, the server will start when your application starts. Here’s how you can do it:

Step-by-Step Guide

  1. Modify the Startup class: Update your Startup class to include a method that starts the Express.js server. This method will be called during the service configuration.

    using System.Diagnostics;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

public static class Startup
{
    public static IServiceCollection CreateServices()
    {
        var services = new ServiceCollection();

        // Add your service configurations here

        // Start the Express.js server if running locally
        if (IsDevelopmentEnvironment())
        {
            StartExpressServer();
        }

        return services;
    }

    private static bool IsDevelopmentEnvironment()
    {
        string? env = Environment.GetEnvironmentVariable("ENVIRONMENT");
        return env == "Development";
    }

    private static void StartExpressServer()
    {
        var startInfo = new ProcessStartInfo
        {
            FileName = "node",
            Arguments = "server.js",
            WorkingDirectory = @"path\to\your\src\directory",
            RedirectStandardOutput = true,
            RedirectStandardError = true,
            UseShellExecute = false,
            CreateNoWindow = true
        };

        var process = new Process { StartInfo = startInfo };
        process.OutputDataReceived += (sender, args) => Console.WriteLine(args.Data);
        process.ErrorDataReceived += (sender, args) => Console.WriteLine(args.Data);

        process.Start();
        process.BeginOutputReadLine();
        process.BeginErrorReadLine();
    }
}

Explanation

  • StartExpressServer Method: This method uses the Process class to start the Node.js server. It sets up the process to run node server.js in the specified working directory.
  • Environment Check: The CreateServices method checks if the environment is “Development” and starts the Express.js server if it is.

How to Run

  1. Ensure Node.js and Express.js are set up: Make sure your Express.js server is correctly set up and can be started with node server.js.

  2. Run your C# application: When you run your C# application, it will automatically start the Express.js server if the environment is set to “Development”.

Summary

This setup ensures that your Express.js server is automatically started as a precondition when running your C# application in the development environment. This allows you to seamlessly integrate your Node.js server with your C# services.

Step-by-Step Guide to Configure Express.js

  1. Install Node.js and Express.js: First, ensure you have Node.js installed. Then, create a new directory for your Express.js server and navigate to it in your terminal. Run the following commands to initialize a new Node.js project and install Express.js:

    mkdir my-express-server
cd my-express-server
npm init -y
npm install express

  2. Create the Express.js Server: Create a file named server.js in your project directory and add the following code to set up a basic Express.js server:

    const express = require('express');
const app = express();
const port = 3000;

app.get('/', (req, res) => {
    res.send('Hello World!');
});

app.listen(port, () => {
    console.log(`Express server listening at http://localhost:${port}`);
});

  3. Configure the Working Directory: Ensure the WorkingDirectory in your C# Startup class points to the directory where your server.js file is located. For example:

    private static void StartExpressServer()
{
    var startInfo = new ProcessStartInfo
    {
        FileName = "node",
        Arguments = "server.js",
        WorkingDirectory = @"path\to\your\my-express-server\directory",
        RedirectStandardOutput = true,
        RedirectStandardError = true,
        UseShellExecute = false,
        CreateNoWindow = true
    };

    var process = new Process { StartInfo = startInfo };
    process.OutputDataReceived += (sender, args) => Console.WriteLine(args.Data);
    process.ErrorDataReceived += (sender, args) => Console.WriteLine(args.Data);

    process.Start();
    process.BeginOutputReadLine();
    process.BeginErrorReadLine();
}

  4. Run the C# Application: When you run your C# application, it will automatically start the Express.js server if the environment is set to “Development”.

Summary

  • Node.js and Express.js Installation: Ensure Node.js is installed and set up a new Express.js project.
  • Express.js Server Setup: Create a basic Express.js server in server.js.
  • C# Configuration: Update the WorkingDirectory in your C# Startup class to point to your Express.js project directory.

This configuration allows your Express.js server to start automatically when your C# application runs, making it easy to integrate both environments.

The Payoff: Faster Shipping, Fewer 2 AM Pages

Running regression tests while you’re developing is not a nice-to-have. It’s table stakes for teams that ship fast. The moment you have tests, wire them into dev. Don’t wait for QA infrastructure. Don’t wait for “the right time.” Do it now. Your deploy frequency will thank you.

Sources & Further Reading

  1. Shift-left testing — Wikipedia
  2. Microsoft — DevOps test strategy
  3. Test Agent Actor — roman-g/test-runner
  4. DORA — Four Key Metrics

See also: CI/CD Pipelines for Test Automation (Jun 2026) — where that early regression suite actually lives in the pipeline.