lambda_initial_version.py

import smartpy as sp

@sp.module
def main():

    def newPrice(oldPrice):
        return oldPrice + sp.split_tokens(oldPrice, 10, 100) 

    def newPrice2(oldPrice):
        return oldPrice + sp.tez(1)
    
    class NftForSale(sp.Contract):
        
       def __init__(self, owner, metadata, price):
           self.data.author = owner
           self.data.owner = owner
           self.data.metadata = metadata
           self.data.price = price
           self.data.priceUpdateRule = newPrice
    
       @sp.entrypoint
       def buy(self):
           assert sp.amount == self.data.price
           sp.send(self.data.owner, self.data.price)
           self.data.owner = sp.sender
           self.data.price = self.data.priceUpdateRule(self.data.price)

       @sp.entrypoint
       def changeRule(self, newRule):
           self.data.priceUpdateRule = newRule

@sp.add_test()
def test():
    alice = sp.test_account("alice").address
    bob = sp.test_account("bob").address
    eve = sp.test_account("eve").address
    scenario = sp.test_scenario("Test", main)
    c1 = main.NftForSale(owner = alice, metadata = "Gwen's nft", price=sp.mutez(5000000))
    scenario +=c1
    scenario.h3(" Testing increasing price")
    c1.buy(_sender = bob, _amount = sp.mutez(5000000))
    c1.buy(_sender = eve, _amount = sp.mutez(5500000))
    c1.buy(_sender = alice, _amount = sp.mutez(6000000), _valid = False)
    scenario.verify(c1.data.price == sp.mutez(6050000))
    c1.changeRule(main.newPrice2, _sender = alice)
    c1.buy(_sender = bob, _amount = sp.mutez(6050000))
    scenario.verify(c1.data.price == sp.mutez(7050000))