Streamlining User Acceptance Testing (UAT) by Mapping New Components to Old Workflows

The most expensive phase of any legacy modernization project isn't the coding—it's the User Acceptance Testing (UAT). When a $50 million core banking migration or a healthcare claims system overhaul fails, it rarely happens because the code won't compile. It fails because, during UAT, the end-users realize the new system doesn't actually match the "undocumented" reality of the old one.

In an era where 70% of legacy rewrites fail or exceed their timelines, the primary bottleneck is functional drift. We spend 18 to 24 months trying to replicate a system that no one fully understands because 67% of these legacy environments lack any meaningful documentation. We are essentially performing digital archaeology with a blindfold on.

TL;DR: Streamlining UAT requires moving away from manual "stare and compare" testing toward Visual Reverse Engineering, where recorded legacy workflows are mapped 1:1 to modern React components to ensure functional parity from day one.

The $3.6 Trillion Documentation Gap#

The global technical debt stands at a staggering $3.6 trillion. For the Enterprise Architect, this isn't just a number; it’s a daily tax on innovation. When we attempt to modernize, we encounter the "Black Box" problem. The legacy system—often a monolith built in Java Swing, PowerBuilder, or older web frameworks—contains decades of "shadow logic": edge cases handled by specific button click sequences that were never written down.

Traditional UAT relies on business analysts writing test scripts based on what they think the system does. This leads to the "40-hour screen trap." On average, it takes a manual team 40 hours to document, design, and verify a single complex legacy screen. With Replay, that time is compressed to 4 hours.

Modernization Methodology Comparison#

Mapping Workflows: From Video to React#

The core philosophy of Replay is that the video is the source of truth. Instead of asking a developer to guess how a legacy insurance form calculates a premium, we record a real user performing the task.

Replay’s AI Automation Suite then performs Visual Reverse Engineering. It doesn't just take a screenshot; it extracts the underlying state, the API triggers, and the component hierarchy. This allows us to map the "Old Workflow" to the "New Component" with mathematical precision.

Step 1: Workflow Recording (The Audit Trail)#

In regulated industries like Financial Services or Government, you cannot afford to miss a single validation rule. We start by recording the "As-Is" process. This recording becomes the blueprint for the UAT criteria.

Step 2: Component Extraction#

Replay’s Blueprints editor analyzes the recording to identify UI patterns. It recognizes that a specific grid in a legacy Delphi app serves the same functional purpose as a modern DataGrid in React.

Step 3: Generating the Modern Equivalent#

Replay generates documented React components that maintain the business logic of the original. This isn't just "spaghetti code" conversion; it's clean, type-safe TypeScript.

typescript
// Example: Generated React component from a legacy claims processing screen
// Replay extracted the conditional logic directly from observed user interactions
import React, { useState, useEffect } from 'react';
import { LegacySystemAPI } from '@internal/legacy-bridge';
import { ModernButton, ModernInput, ValidationAlert } from '@replay-library/ui';

interface ClaimsFormProps {
  claimId: string;
  onSuccess: (data: any) => void;
}

export const MigratedClaimsProcessor: React.FC<ClaimsFormProps> = ({ claimId, onSuccess }) => {
  const [state, setState] = useState({ status: 'pending', data: null });
  const [isHighValue, setIsHighValue] = useState(false);

  // Business logic preserved from legacy: High-value claims > $5000 
  // require an additional 'SupervisorID' field which was undocumented.
  const handleAmountChange = (amount: number) => {
    if (amount > 5000) {
      setIsHighValue(true);
    }
  };

  return (
    <div className="p-6 border-l-4 border-blue-500">
      <h2 className="text-xl font-bold">Claim Verification: {claimId}</h2>
      <ModernInput 
        label="Claim Amount" 
        onChange={(e) => handleAmountChange(Number(e.target.value))} 
      />
      
      {isHighValue && (
        <div className="bg-yellow-50 p-4 mt-4">
          <ValidationAlert message="Supervisor Override Required for claims > $5,000" />
          <ModernInput label="Supervisor ID" type="password" />
        </div>
      )}
      
      <ModernButton onClick={() => onSuccess(state.data)}>
        Sync to Legacy Core
      </ModernButton>
    </div>
  );
};

💰 ROI Insight: By automating the extraction of components, enterprises save an average of 70% on development time. More importantly, the UAT phase is shortened because the "Supervisor Override" logic (shown above) was captured visually, not rediscovered during a failed test cycle.

Eliminating UAT Subjectivity with "Flows"#

The biggest friction point in UAT is the argument between the user and the developer: "It doesn't feel right."

Replay eliminates this subjectivity through its Flows feature. A "Flow" is a visual map of the architecture. It connects the legacy screen recording to the new React component and the corresponding API contract.

The Automated UAT Pipeline#

1. •Baseline: Record the legacy workflow (e.g., "Onboarding a New Client").
2. •Mapping: Replay maps every input field and button to the new React Library.
3. •Validation: Replay generates E2E tests (Playwright/Cypress) that mimic the exact timings and data inputs of the legacy recording.
4. •Verification: If the modern system produces the same API payload as the legacy system, the UAT step is marked as "Passed."

⚠️ Warning: Do not attempt to "improve" the UX during the initial migration phase. Functional parity must be achieved first. Replay allows you to modernize the tech stack while keeping the workflow identical, reducing the cognitive load on users during UAT.

Technical Debt Audit and API Contracts#

Modernization often breaks because the backend expectations haven't changed, but the frontend delivery has. Replay’s AI suite doesn't just look at the UI; it intercepts the network traffic during the recording phase to generate API Contracts.

If your legacy system expects a specific SOAP payload or a non-standard JSON structure, Replay documents this automatically. This ensures that when the "New Component" is plugged into the "Old Workflow," the data integrity remains intact.

json
// Replay Generated API Contract for UAT Validation
{
  "endpoint": "/api/v1/legacy/claims/submit",
  "method": "POST",
  "expected_payload": {
    "claim_ref": "string (regex: ^[A-Z]{3}-\\d{4}$)",
    "amount": "float",
    "timestamp": "ISO8601",
    "metadata": {
      "legacy_flag": "boolean",
      "workstation_id": "string"
    }
  },
  "observed_latency_baseline": "450ms"
}

Scaling to Regulated Environments#

For industries like Healthcare (HIPAA) and Financial Services (SOC2), the "archaeology" method of modernization is a compliance nightmare. Manual documentation is prone to human error, and missing a single validation check can result in millions in fines.

Replay offers On-Premise deployment, ensuring that sensitive user data recorded during the workflow extraction never leaves your firewall. This allows your architects to see the "Black Box" clearly without compromising security.

Step-by-Step Tutorial: Using Replay for UAT Mapping#

Step 1: The Recording Session#

Invite a subject matter expert (SME) to perform their daily tasks while Replay records the session. Replay captures the DOM changes, network requests, and visual states.

Step 2: Library Generation#

Replay analyzes the recording and identifies reusable patterns. It populates your Library, creating a standardized Design System based on the legacy functional requirements.

Step 3: Blueprinting the Flow#

In the Blueprints editor, the Architect maps the sequence of screens. You can literally drag and drop the legacy recording onto the new React component tree to verify coverage.

Step 4: E2E Test Generation#

Replay outputs a suite of E2E tests. These are not generic tests; they are specific to the data used in the recording.

typescript
// Replay-generated Playwright test for UAT Parity
import { test, expect } from '@playwright/test';

test('UAT Parity: Insurance Claim Submission', async ({ page }) => {
  await page.goto('/modern/claims');
  
  // These inputs are derived from the 'Legacy_Session_042.replay' recording
  await page.fill('input[name="claim_ref"]', 'MED-9928');
  await page.fill('input[name="amount"]', '6200');
  
  // Replay identified that this button triggers the Supervisor Override
  await expect(page.locator('text=Supervisor ID')).toBeVisible();
  
  await page.fill('input[name="supervisor_id"]', 'ADMIN_123');
  await page.click('button[type="submit"]');
  
  // Verify API parity
  const response = await page.waitForResponse('**/api/v1/legacy/claims/submit');
  expect(response.status()).toBe(200);
});

Step 5: The Final Sign-off#

Instead of a 3-week UAT cycle, the SME reviews the Replay "Side-by-Side" view. They see the legacy recording on the left and the modern component on the right. When the automated tests pass and the visual states match, the screen is certified for production.

Frequently Asked Questions#

How long does legacy extraction take?#

While a manual rewrite of a complex enterprise screen takes 40+ hours, Replay reduces this to approximately 4 hours. For a standard 50-screen application, you are looking at weeks rather than months for the initial modernization.

What about business logic preservation?#

Replay’s AI Automation Suite extracts logic by observing state changes. If clicking "Option A" consistently hides "Field B" in the legacy system, Replay identifies this dependency and reflects it in the generated React code and API contracts.

Does this replace my QA team?#

No. It empowers your QA team to focus on new features rather than spending 18 months verifying that the "Old System" still works. It shifts the focus from "finding bugs" to "verifying intent."

Can Replay handle mainframe or terminal-based systems?#

Yes. Through visual analysis and terminal stream recording, Replay can map green-screen workflows to modern web interfaces, providing a bridge between COBOL-based backends and React-based frontends.

---

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