Testing and Diagnostics

The test project shows the best patterns for keeping behavior deterministic.

Useful tools in the library

ProfilePrepare for coarse timing of preparation work
SetLocale to stabilize locale-sensitive segmentation
ClearCache to reset cached font state between tests

Useful patterns in the repo

Override measurement in tests so widths are deterministic
Assert both Layout and LayoutWithLines
Compare streamed LayoutNextLine output with batched line materialization
Cover multilingual strings, preserved whitespace, tabs, soft hyphens, and zero-width breaks

What the parity suite covers

The current parity tests are a useful support matrix for product code and docs:

collapsed whitespace in Normal
preserved spaces, tabs, and hard breaks in PreWrap
hanging trailing whitespace
discretionary soft hyphens
zero-width break opportunities
URL-like and punctuation-chain tokenization
Arabic, Devanagari, Myanmar, CJK, and Hangul punctuation attachment
mixed-direction text
locale-aware Thai segmentation
alignment between Layout, LayoutWithLines, LayoutNextLine, and WalkLineRanges

Profiling advice

Use ProfilePrepare when you are investigating:

how much of your cost is in analysis versus measurement
whether a text source should be prepared once and cached
whether a host is reparsing or remeasuring too often

If you change tokenization or break behavior, the parity tests are the first place to verify regressions.