collapseWhitespace static method
Collapses every run of whitespace (spaces, tabs, newlines) to a single
space and trims the result. Used to compare code that dart format may
have re-indented or wrapped across multiple physical lines, so matching
stays stable regardless of formatting.
Implementation
static String collapseWhitespace(String input) =>
input.replaceAll(RegExp(r'\s+'), ' ').trim();