Perspective
Testing text resize, zoom and reflow
Check what happens when people need content larger instead of assuming responsive design has already solved it.
Responsive design and accessibility under enlargement overlap, but they are not the same test.
Test browser zoom
On web content, increase zoom through the levels relevant to your conformance target and supported environment. Check content and functionality rather than only whether the page technically renders.
Test narrow reflow
Look for horizontal scrolling, clipped controls, overlapping text, fixed headers covering content and reading orders that stop making sense.
Test text spacing separately
Changing line height, letter spacing, word spacing and paragraph spacing can expose failures that ordinary zoom does not.
Test platform text size
For mobile apps and relevant mobile web experiences, test system text-size settings including supported accessibility sizes.
What to record
Capture viewport/device, zoom or text setting, exact loss of content/function and screenshots where visual collision is the evidence.
What a pass establishes
The tested content/function survived the tested enlargement or spacing condition.
What it does not establish
One viewport or zoom level does not prove every responsive state, orientation or platform accessibility-size configuration works.
Follow the evidence trail
Start with the enlargement barrier → try the resize/reflow Lab → inspect the applicable WCAG 2.2 Distinguishable criteria.