Beyond UI: Backend Logic-Driven Test Automation

Test Automation First Steps: Why UI Testing?

Where should test automation begin?

Many enterprises experiencing the limitations of manual testing are considering test automation adoption. The first choice they typically make is UI test automation.

Why start with UI testing?

The primary reason is that it's intuitive and easy to understand:

• Clicking screens and entering data is visually comprehensible, making automation easy to imagine

• Test scenarios can be easily drawn from a user perspective

• Repetitive and time-consuming manual tests can be immediately replaced

However, complex business logic systems like ERP, financial systems, and large-scale e-commerce platforms require a different approach.

Limitations of UI Test Automation

While UI test automation provides clear value, it encounters limitations in complex business systems like ERP.

Key Technical Limitations:

• Flaky Tests: Sensitive to environmental changes causing intermittent failures (network delays, loading speed differences)

• High Maintenance Costs: Every UI change requires massive updates to related test cases

• Slow Execution Speed: Wait times due to browser startup and page loading

• Limited Validation Scope: Only validates what's visible on screen, unable to verify backend logic

The Missing Core: Service Layer Testing

While the technical limitations of UI test automation are important, most enterprises aren't considering the more critical service layer testing.

What is Service Layer Testing?
It verifies that each business logic functions correctly step by step. For example, checking the entire process where customer order data is accurately stored → inventory is deducted → accounting entries are generated.

Why don't enterprises consider service layer testing?

1. Not Visible: What happens behind the screen is difficult to intuitively grasp

2. Technical Barriers: More complex and requires specialized skills compared to UI automation

3. Lack of Tools: Few tools make service layer automation easy

Consequently, focus remains only on the relatively accessible UI automation.

The Inverted Test Pyramid Trap

The result of this phenomenon is the inverted test pyramid.

Enterprise Test Investment Status

Enterprise test investment has the opposite distribution from where bugs actually occur. Most bugs occur in the Service Layer (backend logic), but test investment is only 10%, the lowest proportion.

Current Test Investment Distribution:

• Manual Testing (65%) | Slowest and most fragile

• UI Layer Automation (25%) | Unstable with high maintenance costs

• Service Layer Automation (10%) | Most important but neglected

Structural Change Toward Backend Logic-Centric Testing

The key is shifting to an inverted pyramid that focuses on important backend logic testing rather than easily accessible UI testing.

Ideal Distribution:

• Service Layer Automation (65%) | Business logic-centric verification

• UI Layer Automation (25%) | User experience verification

• Manual Testing (10%) | Final confirmation

Why Backend Automation is Essential in ERP Systems

In complex business systems like ERP, backend logic-based testing is particularly crucial.

ERP's Complex Business Logic

Even a single order processing involves:

• Data storage/updates across 10+ tables

• Discount rate calculations considering customer grade, product category, seasonal policies

• Simultaneous processing of inventory deduction, accounting entry generation, and external system data transmission

Actual Error Cases:

• Price calculation errors in tens of thousands of automotive part combinations

• Calculation logic errors when multiple discount coupons are applied simultaneously

• Missing special order types from various sales channels

These problems cannot be detected through UI testing. Even when screens display normally, incorrect calculations or omissions occur in the backend.

What needs verification in ERP:

• Is input data stored in the correct tables with proper formatting?

• Are complex business rules (discounts, taxes, fees, etc.) calculated accurately?

• Do inventory deduction, accounting processing, and approval processes execute sequentially and correctly?

• Is data integration with external systems performed according to exact specifications?

For such verification, test automation for backend business logic that occurs behind the scenes is crucial.

How to Start ERP Backend Test Automation?

Existing UI-centric tools have limitations for automating complex ERP backend logic. Specialized tools capable of service layer verification based on actual operational data are needed. PerfecTwin is an ERP-specialized test automation solution developed to meet these requirements.

PerfecTwin's Key Differentiators:

1. Real Transaction Data-Based Service Layer Testing

• Backend logic verification using actual operational data, not samples

• Service layer accuracy verification including DB storage, calculation logic, and integration processing

2. Server Direct Transmission Method

• Business logic verification by directly transmitting data to servers without screen clicks

• Eliminates browser startup and screen loading wait times

3. Complex ERP Integration System Automation

• Interface testing with simulators even when integration environments aren't built

• ERP-external system integration verification (supporting various integration methods: SOAP, REST, RFC, etc.)

Conclusion: Test Automation Paradigm Shift

ERP testing depends on how accurately and efficiently we can verify business logic beyond the screen. That's the core of successful ERP test automation.

In the next article, we'll introduce automation scope selection strategies under the theme "Test Automation Strategy: What Should Be Automated?"