runAll method Null safety
Implementation
@mustCallSuper
Future<void> runAll() async {
await testJson();
await testFloatValues();
await testNumbers();
debugPrint('');
debugPrint('*** $testsRun self tests run. $errorsSeen errors seen');
debugPrint('');
if (errorsSeen > 0) {
throw CalculatorError(9);
}
}