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