15. As a user, I want to be alerted when I’m entering an item that's already on my list when its either singular or plural

[sar-mko]

Summary

Users shouldn't be able to add the plural or singular version of an item, if the singular or plural version is there. If they try to do this, we need to show them an error message that explains this. This extends the feature added in issue #10 .

Acceptance criteria

• Show an error message if the user tries to add a singular item when the plural version exists on the user's list. For instance, if the list contains apples and the user adds apple.
• Show an error message if the user tries to add a plural item when the singular version exists on the user's list. For instance, if the list contains apple and the user adds apples.
• The check works for exact matches regardless of case, and outside space.
• When a user adds a similar item that isn't exact, they are given the choice to add the item. (ex. app#le, apple ; bananas, ban ana)

Notes

• The idea is that plural and singular versions are recognized as "exact" matches, but if there are random spaces and characters -> users are given the option to add an item
• There are plural words that don't have a similar fix (ex. strawberries, strawberry), so a first approach can be to address simple plural words that add -s (apple, apples)