Software Engineering
Test Automation Strategy: Building Quality into Every Release
Manual regression testing limits how often you can release. A balanced automation strategy improves quality and speed — if it is designed around the right layers.
Key takeaways
- Assess business value and technical health before choosing a strategy.
- Prefer incremental patterns such as the strangler fig over big-bang rewrites.
- A modular monolith is often a better target than microservices.
- Invest in automated testing before changing core logic.
Why modernise
Legacy applications create risk through unsupported technology, scarce skills, security weaknesses and slow change. Yet they often encode years of business rules that are poorly documented.
Assess the portfolio
Score each application on business value and technical health. High-value, poor-health applications are modernisation priorities; low-value ones may be retired or replaced with SaaS.
Modernization options
| Option | Description |
|---|---|
| Encapsulate | Expose functions through APIs without changing the core |
| Rehost / replatform | Move to modern infrastructure with minimal code change |
| Refactor | Improve structure without changing behaviour |
| Re-architect | Move to modular or service-based architecture |
| Rebuild | Rewrite with modern technology |
| Replace | Adopt a commercial or SaaS product |
The strangler fig pattern
Place an API or routing layer in front of the legacy system and replace functions one at a time. Each new component goes live independently, reducing risk and delivering value continuously.
Microservices or modular monolith?
Microservices bring independent scaling and deployment but add operational complexity. Many organizations get better results from a well-structured modular monolith, splitting services out only where scale or team autonomy justifies it.
Testing and data
Build characterisation tests that capture current behaviour before changing it. Plan data migration early — it is frequently the hardest and riskiest part.
Measuring outcomes
Track deployment frequency, lead time for changes, change failure rate, recovery time, infrastructure cost and the reduction of unsupported components.
Organizing teams for modernisation
Align teams to business capabilities rather than technical layers. Each team owns a slice of functionality end to end — from legacy behaviour analysis through to the new implementation and its operation.
Managing risk during transition
| Risk | Mitigation |
|---|---|
| Behaviour differences | Characterisation tests and parallel runs |
| Data inconsistency | Clear system of record for each data domain |
| Performance regression | Load testing before switching traffic |
| Knowledge loss | Document rules as they are discovered |
How NAZZTEC helps
Our software engineering teams assess application portfolios, design target architectures, deliver incremental modernisation with automated testing and support applications after go-live.
Next step: see our Software Solutions and Software & Application Solutions.
Frequently asked questions
Should we rewrite from scratch?
Rarely. Full rewrites take longer than expected and must chase a moving target. Incremental approaches are safer.
How long does modernization take?
Value should be delivered within months; full modernization of a large system can take several years in increments.
Can low-code help?
Yes, for workflows and front-ends around legacy cores, provided it is governed properly.
NAZZTEC Editorial TeamWritten and reviewed by NAZZTEC practitioners. This briefing is general guidance, not legal advice.
