The Role of Visual Replay in Accelerated User Acceptance Testing (UAT)

User Acceptance Testing (UAT) is where legacy modernization projects go to die. It is the final, most expensive stage of the software development lifecycle, yet it is frequently treated as a forensic investigation into why the new system doesn't "feel" like the old one. When 70% of legacy rewrites fail or exceed their timelines, the culprit isn't usually the new tech stack—it’s the lack of functional parity caused by undocumented legacy behavior.

In the enterprise, the "black box" of legacy software is a $3.6 trillion technical debt problem. Most modernization efforts rely on "archaeology"—developers digging through decades-old COBOL, Java, or Delphi code to guess how a screen should behave. This manual approach takes an average of 40 hours per screen. By the time the modern version reaches UAT, the business users reject it because a critical, undocumented edge case was missed.

TL;DR: The Role of Visual Replay in UAT is to transform legacy systems from undocumented black boxes into verified, modern codebases by using recorded user workflows as the definitive source of truth, reducing modernization timelines from years to weeks.

The Role of Visual Replay in Bridging the Documentation Gap#

The primary reason UAT cycles drag on for months is the documentation gap. Statistics show that 67% of legacy systems lack any form of up-to-date documentation. When an Enterprise Architect is tasked with moving a 20-year-old claims processing system to React, they aren't just moving code; they are moving tribal knowledge.

The Role of Visual Replay is to capture this knowledge at the source. Instead of interviewing retired developers or guessing at business logic, Replay allows teams to record real user workflows. This recording becomes the "Blueprints" for the new system.

Why Manual Documentation Fails in UAT#

1. •The "Hidden Logic" Problem: Legacy systems often have complex validation rules hidden in the UI layer that aren't documented in the backend API.
2. •User Habituation: Business users in Financial Services or Healthcare have "muscle memory" for specific workflows. If the new UI breaks this flow, UAT fails.
3. •The Timeline Trap: Manual documentation adds months to the discovery phase, pushing the 18-month average enterprise rewrite timeline even further.

The Role of Visual Replay in Generating Functional Parity#

Functional parity is the holy grail of UAT. To achieve it, Replay doesn't just record pixels; it records the DOM state, network calls, and component hierarchy. This allows the Replay AI Automation Suite to generate modern React components that match the legacy behavior exactly.

From Video to React: The Extraction Process#

When a user records a workflow in Replay, the platform extracts the underlying architecture. It identifies the "Flows" and maps them to a modern "Library" (Design System). This ensures that the code delivered to UAT isn't just a visual clone, but a technically sound, maintainable component.

typescript
// Example: React component generated by Replay from a legacy insurance portal recording
// The AI preserves the complex conditional logic found during the visual capture.

import React, { useState, useEffect } from 'react';
import { TextField, Select, Button, Alert } from '@replay-ui/core';

interface ClaimData {
  policyNumber: string;
  claimType: 'Auto' | 'Home' | 'Life';
  incidentDate: string;
  isEmergency: boolean;
}

export const LegacyClaimFormMigrated: React.FC = () => {
  const [formData, setFormData] = useState<Partial<ClaimData>>({});
  const [validationError, setValidationError] = useState<string | null>(null);

  // Logic extracted from legacy network intercept: 
  // Policy must be validated against the 'PRD-VAL-01' endpoint
  const handleValidation = async () => {
    const isValid = await validatePolicy(formData.policyNumber);
    if (!isValid) {
      setValidationError("Legacy System Error: Policy number format invalid for region.");
    }
  };

  return (
    <div className="modern-container p-6">
      <h2 className="text-2xl font-bold mb-4">Submit New Claim</h2>
      <TextField 
        label="Policy Number" 
        onChange={(val) => setFormData({...formData, policyNumber: val})} 
      />
      {/* Replay identified this conditional select from the legacy UI behavior */}
      {formData.policyNumber && (
        <Select 
          options={['Auto', 'Home', 'Life']} 
          label="Claim Type"
          onChange={(val) => setFormData({...formData, claimType: val as any})}
        />
      )}
      <Button onClick={handleValidation} variant="primary">
        Validate & Continue
      </Button>
      {validationError && <Alert type="error">{validationError}</Alert>}
    </div>
  );
};

💰 ROI Insight: By using Replay to generate components, enterprise teams save an average of 70% in development time. A project slated for 24 months can be completed in under 6 months.

Accelerating UAT with Automated E2E Test Generation#

One of the most significant roles of Visual Replay is the automated generation of End-to-End (E2E) tests and API contracts. In a traditional modernization project, QA teams wait until a feature is "done" to write tests. With Replay, the test is created the moment the legacy workflow is recorded.

Step 1: Assessment and Recording#

The process begins by identifying the high-risk workflows in the legacy system (e.g., a complex trade execution in a Fintech app). A subject matter expert (SME) records the "happy path" and common edge cases using the Replay recorder.

Step 2: Extraction and AI Mapping#

Replay’s AI Automation Suite analyzes the recording. It maps legacy HTML elements to modern Design System components. It also documents the API contracts—even if the legacy system uses SOAP or undocumented REST endpoints.

Step 3: Blueprinting the Modern UI#

Architects use the "Blueprints" editor to refine the generated code. This is where technical debt is audited. Replay flags redundant logic and suggests optimizations while maintaining the functional requirements captured in the recording.

Step 4: Automated UAT Validation#

Replay generates Playwright or Cypress tests based on the original recording. These tests are run against the modern implementation. If the modern screen deviates from the legacy recording, the test fails immediately—long before a human user ever sees it.

javascript
// Generated E2E Test (Playwright) from Replay Recording
// This ensures functional parity between legacy and modern versions during UAT.

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

test('verify functional parity for claim submission flow', async ({ page }) => {
  // Navigate to the migrated screen
  await page.goto('/claims/new');

  // Step 1: Policy Validation (Captured from legacy workflow)
  await page.fill('input[name="policyNumber"]', 'POL-88234-X');
  await page.click('button:has-text("Validate")');
  
  // Assert the specific legacy behavior: The 'Claim Type' dropdown appears only after validation
  const claimTypeSelect = page.locator('select[name="claimType"]');
  await expect(claimTypeSelect).toBeVisible();

  // Step 2: Data Entry
  await claimTypeSelect.selectOption('Auto');
  await page.fill('input[name="incidentDate"]', '2023-10-27');

  // Step 3: Submission
  await page.click('button:has-text("Submit")');

  // Assert API parity
  const response = await page.waitForResponse(res => res.url().includes('/api/v1/claims'));
  expect(response.status()).toBe(201);
});

⚠️ Warning: Never skip the API Contract generation phase. Modernizing the UI without documenting the legacy API dependencies is the fastest way to break a system during production cutover.

The Role of Visual Replay in Regulated Environments#

For industries like Government, Telecom, and Insurance, security is a non-negotiable barrier to modernization. The Role of Visual Replay extends beyond code generation into compliance and auditability.

• •SOC2 & HIPAA-Ready: Replay is built for enterprise security, ensuring that PII (Personally Identifiable Information) can be masked during the recording and extraction process.
• •On-Premise Availability: For organizations with strict data residency requirements (e.g., central banks or defense contractors), Replay can be deployed entirely on-premise.
• •Technical Debt Audit: Replay provides a comprehensive audit of technical debt, identifying which parts of the legacy system are "dead code" and don't need to be migrated, further reducing the UAT surface area.

Eliminating the "Black Box" with Visual Documentation#

Traditional UAT relies on users remembering how things used to work. Replay replaces memory with evidence. The "Flows" feature provides a visual map of the entire system architecture, showing how different screens and components interact.

The Impact on Stakeholder Confidence#

When a VP of Engineering can show a side-by-side comparison of the legacy recording and the modern implementation—backed by passing E2E tests—the "fear factor" of modernization disappears. The role of Visual Replay is to provide the transparency needed to sign off on a project with confidence.

• •For CTOs: Reduced risk of project failure and faster time-to-market.
• •For Architects: A clear, documented path from legacy mess to modern React.
• •For Developers: No more manual archaeology or "guessing" at requirements.
• •For Business Users: A modern system that actually works the way they need it to.

Frequently Asked Questions#

How long does legacy extraction take with Replay?#

While manual documentation and coding take roughly 40 hours per screen, Replay reduces this to 4 hours. For a standard enterprise application with 50-100 screens, this shifts the timeline from 18-24 months down to a matter of weeks.

What about business logic preservation?#

Replay captures the outcomes of business logic by monitoring state changes and network traffic. Our AI Automation Suite then reconstructs this logic in the modern component. During the "Blueprints" phase, developers can review and refine this logic to ensure 100% accuracy.

Does Replay work with extremely old systems (e.g., Mainframe terminals)?#

Yes. As long as the system can be accessed via a web browser or a terminal emulator that runs in a browser environment, Replay can record the session and begin the reverse engineering process.

Can we use our own Design System?#

Absolutely. Replay’s "Library" feature allows you to upload your own React component library. The extraction engine will then map legacy elements directly to your specific modern components.

---

Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.