createFailMessage method
Create a fail message.
Implementation
String createFailMessage(TesterStateMachine stateMachine) {
final message = StringBuffer()
..writeln('Expected State: ${afterState.runtimeType}')
..writeln('Actual State: ${stateMachine.state.runtimeType}')
..write('Expected SideEffect: ')
..writeln(createdSideEffect.map((e) => e.runtimeType).toList())
..write('Actual SideEffect: ')
..writeln(
stateMachine.createdSideEffect.map((e) => e.runtimeType).toList(),
);
return message.toString();
}