In French supermarkets it is common to see packs of water bottles that people have opened to take out one or two - is that legal?
Yes, according to the Code de la Consommation, which states shops cannot insist on you buying a certain quantity of a product.
You could even break in half a block of eight yoghurts if you only want four - on condition that you do not damage the individual packaging of the others, for example by tearing the covers of the pots.
The exception to this where a quantity of identical items are sold inside the same packaging - for example a box of six eggs or a pack of two slices of ham.
Knowing your shopping rights can be useful to make sure you make the most of shopping and stay on the right side of the law.
Another example is tasting to see if you like a product. If you taste a food without having been invited to do so that is theft but to merely open a food pack, intending to pay for it, is acceptable.
As for testing a deodorant or similar personal hygiene product, if you can do so without damaging the packaging you can open it and sniff it, but that is all.
When it comes to price, if the shop has promoted an item with a leaflet as having a certain price, they must sell it at that price.
If you damage goods accidentally in a supermarket the Code Civil states you should not have to pay. Most shops will be covered by insurance for such breakages.
Shops are entitled to require a minimum amount before you can pay by card - but only if they put a notice near to the check-out which mentions this limit.
Finally, if you notice that goods you bought were past their sell-by date, you have the right to take them back for an exchange or refund.