1. Test the entire checkout journey, not just the payment transaction
The biggest mistake organisations make is treating payment testing as “did the card go through?”
David argues that’s far too narrow.
A real checkout includes:
- POS software
- Barcode scanners
- Receipt printers
- Payment terminal
- Cash handling (where applicable)
- Customer interaction
If you only test one component in isolation, you can successfully process a payment while still delivering a broken customer experience. The objective is to validate the entire customer journey, because that’s what customers actually experience.
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2. Simulated terminals are useful - but they’re not reality
“When was the last time you paid on a simulated terminal when you went to Tesco?”
His point is simple:
Retailers deploy physical devices, not simulations.
Simulators are faster and easier, but they cannot accurately reproduce:
- firmware changes
- hardware behaviour
- PIN entry
- card insertion
- receipt printing
- real-world device interactions
For anything being deployed into stores - or for certification - testing should happen on the actual hardware.
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3. Lack of test coverage is one of the industry’s biggest hidden risks
Many retailers believe they’re testing thoroughly because they have dozens of automated tests.
David argues the opposite.
Often they’re missing:
- international cards
- foreign issuers
- DCC scenarios
- different payment methods
- edge cases
A solution that works perfectly with UK Visa cards might fail for an overseas Mastercard customer.
Automation allows organisations to expand coverage from tens of scenarios into hundreds without multiplying manual effort.
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4. Start simple, then expand
You don’t automate every possible payment journey on day one.
David recommends:
- Purchase transactions
- Refunds
- Most common payment methods
- Highest-volume hardware
- Edge cases afterwards
In other words:
Automate the journeys that matter most first, then continuously widen the safety net.
This makes automation practical instead of overwhelming.
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5. Every technology change introduces payment risk
Modern payment environments are constantly evolving.
New:
- firmware
- payment applications
- payment terminals
- wallets
- wearables
- contactless technologies
Each seemingly small change can alter how a transaction behaves.
David’s message is that testing shouldn’t be viewed as something you do before launch - it should become an ongoing capability that evolves alongside your payment estate.