what about making a transaction that will appear then will never be confirmed

can u please tell me can i send a fake bitcoin transaction if its possible how it works ?
i am using this information for school project

does testnet coins take long time to confirm ?

hello please i need 1 testnet bitcoin for my project i cant find any good source if any one have a link please drop it
this is my testnet wallet if u got some to share :mjchw2FLnr45nhyX7N8hkR6w2uEammTJ78
i can buy also