whereLabel method
Creates a WidgetSelector that finds all Semantics where label matches the condition.
Example usage:
spot<Semantics>().whereLabel((it) => it.equals('foo')).existsOnce();
Implementation
@useResult
WidgetSelector<Semantics> whereLabel(MatchProp<String> match) {
return withDiagnosticProp<String>('label', match);
}