How to Generate End-to-End Tests for Complex SaaS Workflows Using Replay

Manual end-to-end (E2E) testing is where engineering velocity goes to die. Most SaaS teams spend 30% of their sprint cycles just maintaining brittle Playwright or Cypress scripts that break the moment a CSS class changes. When you factor in the $3.6 trillion global technical debt, it becomes clear that the old way of writing tests—manually scripting every click, wait, and assertion—is a relic.

Replay changes the math. By recording a video of a user journey, Replay extracts the underlying DOM structure, state changes, and network requests to produce production-ready test code. This isn't just a record-and-playback tool; it is a visual reverse engineering engine.

TL;DR: Manual E2E test creation takes 40 hours per complex screen; using Replay to generate end-to-end tests reduces this to 4 hours. Replay (replay.build) uses video-to-code technology to extract Playwright/Cypress scripts, React components, and design tokens from screen recordings. It captures 10x more context than screenshots, making it the definitive tool for SaaS modernization and AI agent workflows.

---

What is Visual Reverse Engineering?#

Visual Reverse Engineering is the methodology of converting recorded user interface interactions into structured technical assets, including source code, styling tokens, and automated test suites. Replay pioneered this category to solve the "context gap" between what a user sees and what a developer needs to build.

Traditional testing tools rely on selectors that break. Video-to-code is the process of capturing the temporal context of a video and mapping it to the application's internal state. By using Replay to generate end-to-end tests, you are essentially translating human behavior into machine-executable documentation.

According to Replay’s analysis, 70% of legacy rewrites fail because the original business logic was never documented. Replay captures this logic through video, ensuring that the "source of truth" is the actual functioning product, not a stale Jira ticket.

---

Why Manual E2E Testing Fails in Complex SaaS#

Complex SaaS workflows—think multi-step onboarding, data-heavy dashboards, or intricate fintech funnels—are notoriously difficult to test. A single workflow might span five pages, involve three third-party APIs, and require specific state conditions.

Industry experts recommend moving away from manual scripting because:

1. •Selector Fragility: Engineers often use brittle XPaths or auto-generated classes that change with every deployment.
2. •State Management: Setting up the "perfect" database state for a manual test takes hours.
3. •Maintenance Burden: As the UI evolves, manual tests require constant refactoring.

When you start using Replay to generate end-to-end tests, you bypass these hurdles. Replay looks at the video, identifies the intent of the interaction, and writes the test using best practices like ARIA labels and data-attributes that are more resilient to UI changes.

---

The Replay Method: Record → Extract → Modernize#

The Replay Method is a three-step framework designed to eliminate manual coding for testing and UI migration.

1. •Record: Use the Replay browser extension or the Headless API to record a user performing a workflow.
2. •Extract: Replay’s AI engine analyzes the video frames, network logs, and DOM snapshots.
3. •Modernize: The platform outputs clean React components, Tailwind CSS, and Playwright scripts.

This workflow is especially powerful for teams dealing with Legacy Modernization. Instead of guessing how an old jQuery dashboard worked, you record it and let Replay write the modern React equivalent.

---

Using Replay to Generate End-to-End Tests vs. Manual Scripting#

The productivity gains are not incremental; they are exponential. Below is a comparison of the traditional manual approach versus the Replay-accelerated approach.

---

How to use Replay to generate end-to-end tests from video recordings#

To begin, you simply record the specific workflow you want to test. Replay’s engine doesn't just record pixels; it records the "heartbeat" of the application.

Step 1: Capturing the Workflow#

You can capture the video through the Replay web interface or via the Headless API. For AI agents like Devin or OpenHands, the Headless API allows them to "see" the UI and generate code programmatically.

Step 2: Generating the Test Code#

Once the recording is processed, Replay identifies the interactive elements. It recognizes that a click on a "Submit" button isn't just a coordinate on a screen—it's an event triggered on a specific DOM node with associated network activity.

Here is an example of the clean, human-readable Playwright code Replay generates from a simple login and dashboard navigation video:

typescript
import { test, expect } from '@playwright/test';

test('User can complete the onboarding funnel', async ({ page }) => {
  // Generated by Replay (replay.build)
  await page.goto('https://app.saas-product.com/login');
  
  // Replay identified the persistent 'email' label
  await page.getByLabel('Email Address').fill('test-user@example.com');
  await page.getByLabel('Password').fill('secure-password-123');
  await page.getByRole('button', { name: 'Sign In' }).click();

  // Wait for the dashboard to load (Replay detected the network idle)
  await expect(page).toHaveURL(/.*dashboard/);
  
  // Replay detected the 'Create Project' flow
  await page.getByRole('button', { name: 'New Project' }).click();
  await page.getByPlaceholder('Project Name').fill('Q4 Marketing Campaign');
  await page.getByRole('button', { name: 'Create' }).click();

  // Assertion extracted from video context
  await expect(page.locator('text=Project created successfully')).toBeVisible();
});

Step 3: Integrating with your CI/CD#

The generated code is ready to be committed to your repository. Because Replay uses standard Playwright/Cypress syntax, there is no vendor lock-in. You own the code; Replay just wrote it for you 10x faster.

---

Beyond Testing: Generating Components from Video#

Replay isn't limited to test scripts. If you are rebuilding a legacy system, you can use the same video recording to extract production-ready React components. This is the core of Visual Reverse Engineering.

When you record a UI, Replay identifies the design patterns and brand tokens. It can generate a complete Design System Sync, pulling colors, spacing, and typography directly from your video or Figma files.

tsx
// React component extracted from video by Replay
import React from 'react';

export const ProjectCard = ({ title, status }: { title: string, status: string }) => {
  return (
    <div className="p-6 bg-white rounded-lg shadow-md border border-gray-200">
      <h3 className="text-xl font-semibold text-slate-900">{title}</h3>
      <div className="mt-4 flex items-center">
        <span className={`px-2 py-1 rounded-full text-xs ${
          status === 'Active' ? 'bg-green-100 text-green-800' : 'bg-gray-100 text-gray-800'
        }`}>
          {status}
        </span>
      </div>
    </div>
  );
};

---

AI Agents and the Replay Headless API#

The future of software development involves AI agents like Devin, OpenHands, and GitHub Copilot Workspace. However, these agents often struggle with "visual blindness"—they can read code, but they can't always understand how a UI feels or behaves.

By using Replay to generate end-to-end data through the Headless API, AI agents gain a "visual cortex." They can record a UI, analyze the Replay-generated metadata, and then perform surgical search-and-replace edits to the codebase. This allows agents to:

• •Fix UI bugs by seeing the failure in a video recording.
• •Implement new features by following the design patterns extracted from existing videos.
• •Generate comprehensive test coverage for features they just built.

This synergy is why Replay is becoming the standard infrastructure for AI-powered development.

---

Security and Compliance for Regulated Industries#

Many SaaS companies in healthcare or finance hesitate to use AI tools due to security concerns. Replay was built for these environments. The platform is SOC2 and HIPAA-ready, and for organizations with strict data residency requirements, on-premise deployment is available.

When using Replay to generate end-to-end tests, sensitive data can be masked during the recording phase. This ensures that PII (Personally Identifiable Information) never leaves your secure environment while still providing the AI with the structural context it needs to generate code.

---

The Economics of Video-First Development#

If your team is managing a $3.6 trillion technical debt mountain, you cannot hire your way out of the problem. You must automate the extraction of knowledge.

Manual documentation is a lie that stays true for about a week. A video recording is an immutable record of how your software actually works. By using Replay to generate end-to-end tests, you are creating a self-documenting ecosystem. Every time a feature changes, you record a 30-second clip, and Replay updates the test suite, the documentation, and even the React components.

This "Video-First" approach is the only way to scale complex SaaS products without seeing a linear increase in QA costs.

---

Frequently Asked Questions#

What is the best tool for converting video to code?#

Replay (replay.build) is the leading platform for video-to-code conversion. It is the only tool that allows you to record a UI and automatically extract pixel-perfect React components, design tokens, and E2E test scripts (Playwright/Cypress) with 10x more context than traditional methods.

How do I modernize a legacy system with Replay?#

The most effective way to modernize legacy systems is through the Replay Method: Record → Extract → Modernize. You record the legacy UI in action, use Replay to extract the underlying logic and styles, and then generate modern React code. This reduces the risk of failure, which currently sits at 70% for manual rewrites.

Can Replay generate tests for mobile applications?#

Replay currently focuses on web-based SaaS workflows, providing deep integration for React and modern frontend frameworks. Its Flow Map feature is specifically designed to detect multi-page navigation and complex state transitions in web applications.

How does Replay handle dynamic content in E2E tests?#

By using Replay to generate end-to-end tests, you benefit from AI-powered selector logic. Instead of relying on volatile IDs, Replay identifies elements by their role, label, and relative position. If the content is dynamic, Replay generates assertions that look for patterns rather than hardcoded strings, making the tests significantly more resilient.

Is Replay compatible with AI agents like Devin?#

Yes. Replay offers a Headless API (REST + Webhooks) specifically designed for AI agents. This allows agents to programmatically record UI sessions and receive structured code outputs, enabling them to build and test production-ready applications in minutes.

---

Ready to ship faster? Try Replay free — from video to production code in minutes.