Preserve existing requirements covered by tests

PR Checklist

Please check if your PR fulfills the following requirements:

[x] Compile without errors
[x] Run from the command line
[x] Pass all automated test cases
[x] Demonstrate your knowledge of automated testing by implementing both unit and acceptance tests
[x] * Preserve existing requirements:
- [x] * You must enter a comma delimited list of Dish Types with at least one selection
- [x] * The output must print Dish Names in the following order: entrée, side, drink, dessert
- [x] * If invalid selection is encountered, then print "error"
- [x] * Ignore whitespace in the input
- [x] * Each Dish Type is optional (i.e. can have zero if not entered in the input)
- [x] * You can have multiple orders of potatoes (but still no more than 1 each of the other Dish Types)
- [x] * If more than one Dish Type is entered, output it once, followed by "(xN)", e.g. "potato(x2)"
- [x] * Covered By Tests