What changes at senior level
Junior testing is mostly about input validation — what the system accepts and rejects. Senior testing is about behaviour — what the system does across different contexts, states, and environments.
Senior bugs are harder to find because they often require:
- A specific device or viewport size
- A specific browser or OS
- A specific application state (logged out, session expired, partial completion)
- An assistive technology (screen reader, keyboard-only navigation)
Accessibility testing
1 in 4 New Zealanders has a disability. Accessibility bugs are real bugs. At senior level you are expected to:
- Navigate the application using only a keyboard (Tab, Enter, Space, arrow keys)
- Check colour contrast meets WCAG AA (4.5:1 for body text, 3:1 for large text)
- Verify images have descriptive alt text
- Check form fields have visible labels (not just placeholders)
- Verify error messages are announced to screen readers via aria-describedby
Responsive & cross-browser testing
Test at three breakpoints minimum: mobile (375px), tablet (768px), desktop (1280px). Use browser DevTools to emulate. Things that break most often: navigation menus collapsing, tables overflowing, fixed-position elements overlapping content, and font sizes becoming unreadable.
State bugs
State bugs occur when the UI shows stale, inconsistent, or incorrect information based on what happened before. Common patterns:
- Form data persists after logout
- Counter doesn't update after adding/removing items
- Tab shows old content after navigating away and back
- Error state doesn't clear after the user fixes the issue
Beyond the browser
Senior testing moves beyond the visible interface to the layers that power it:
- API testing: Modern apps are often thin frontends talking to complex APIs. Senior testers verify the contract between them — ensuring status codes, schemas, and data types match the spec before the UI even exists.
- Performance testing: Speed is a feature. A senior tester knows when "a bit slow" becomes a business risk. You'll learn to spot heavy images, unoptimised API calls, and memory leaks that degrade the user experience over time.
- Automation strategy: Senior testers decide what to automate (stable regression) vs. what to keep manual (high-risk exploratory). You'll focus on the strategy of automation, not just writing scripts.
Risk-based test prioritisation
You never have time to test everything. Senior testers prioritise by likelihood of failure × impact of failure. A bug on the checkout payment step is higher priority than a bug on the FAQ page, even if both are equally likely to occur. You'll learn to build risk matrices that guide your testing effort.
Next: senior techniques → learning → practice 01.