Testing tickets

Testing tickets requires some extra steps.

The problem with testing tickets

The Tezos protocol has two types of operations:

• Internal operations are created from inside the chain, such as by smart contracts.
• External operations are created from outside the chain, such as by the Octez client, other Tezos clients and SDKs, and in the context of LIGO testing, by functions such as Test.Next.Originate.contract. For more information about the technical implementation, see Semantics of smart contracts and transactions in the Octez documentation.

In the protocol, both external and internal origination and transfer operations contain a piece of michelson code representing the initial storage for the origination or the parameter for the transfer.

Now imagine you have a value of type parameter_ty/storage_ty containing a ticket, that you want to transfer or originate, in the operation data, tickets will be represented in Michelson as pairs:

> ligo compile expression cameligo 'Tezos.create_ticket 0x0202 10n'

(Pair "KT1DUMMYDUMMYDUMMYDUMMYDUMMYDUMu2oHG" 0x0202 10)

ticketer address , ticket value , ticket amount

If we try to apply such an operation, the type wouldn't match: ticket of bytes VS some pair. The protocol would not let you do that since you could be creating a ticket out of nowhere unless the operation happens to be forged from within a contract (i.e. "internally")!

In the testing framework - for now - it means using "proxy-contracts" forging the operations using provided a ticket value and a ticket amount.

Proxy ticket contracts

The LIGO standard library provides a Proxy_ticket module which helps in working with tickets in the Testing framework. Here is the interface of Proxy_ticket:

---

init_transfer accepts:

• a function mk_param which given a ticket must return a value of your parameter type

and returns the typed address of a "transfer proxy-contract" which can then be used to do multiple transfers of tickets with the same ticketer address

---

transfer accepts :

• the typed address of a "transfer proxy-contract"
• the ticket information (value and amount) together with the destination address

and returns a value of type test_exec_result

---

originate accepts:

• the ticket information (value and amount)
• a function mk_storage which given a ticket must return a value of your storage type
• your contract (having a ticket in its storage type)

---

Note: Functions mk_param and mk_storage will be executed in the proxy contract itself

Find more detailed information on the API of Proxy_ticket here

Usages

Transfer

Here is an example using Proxy_ticket.init_transfer and Proxy_ticket.transfer:

1. import the module above as Proxy_ticket
2. define a contract C holding a ticket of string in its parameter type. The contract will just store the value of the received ticket and the address of the sender
3. originate contract C
4. initialize a "transfer proxy-contract" providing a function to build a parameter out of a ticket
5. transfer a ticket with a value "hello" and an amount of 10 to contract C
6. print the storage of contract C
7. transfer a ticket with a value "world" and an amount of 5 to contract C
8. print the storage of contract C

namespace C {

export type param = [ int , ticket<string>]

@entry

function main (p: param, _s: [string , address]) : [list<operation> , [string , address]] {

let [_v,ticket] = p ;

let [[_addr,[v,_t]] , _ticket] = Tezos.read_ticket (ticket) ;

return ([[] , [v, Tezos.get_sender ()]])

};

}

const test_transfer_to_contract = do {

let {addr : main_taddr, code , size } = Test.originate (contract_of(C), ["bye",Test.nth_bootstrap_account (1)], 1mutez) ;

let main_addr = Test.to_address (main_taddr) ;

/* mk_param is executed __by the proxy contract__ */

const mk_param = (t:ticket<string>) : C.param => { return [42,t] } ;

/* Use this address everytime you want to send tickets from the same proxy-contract */

/* initialize a proxy contract in charge of creating and sending your tickets */

let proxy_taddr = Test.Proxy_ticket.init_transfer (mk_param) ;

Test.log (["poxy addr:", proxy_taddr]) ;

/* ticket_info lets you control the amount and the value of the tickets you send */

let ticket_info1 = ["hello", 10n];

/* we send ticket to main through the proxy-contract */

Test.Proxy_ticket.transfer (proxy_taddr, [ticket_info1,main_addr]) ;

Test.log (Test.get_storage (main_taddr)) ;

let ticket_info2 = ["world",5n] ;

Test.Proxy_ticket.transfer (proxy_taddr, [ticket_info2,main_addr]) ;

Test.log (Test.get_storage (main_taddr));

};

result:

> ligo run test transfer_ticket.mligo

("poxy addr:" , KT1QGANLjYsyJmw1QNww9Jkgb4ccQr6W2gsC)

("hello" , KT1QGANLjYsyJmw1QNww9Jkgb4ccQr6W2gsC)

("world" , KT1QGANLjYsyJmw1QNww9Jkgb4ccQr6W2gsC)

Everything at the top-level was executed.

- test_transfer_to_contract exited with value ().

Note: note that the sender (stored in the contract) matches the address of the proxy contract

Origination

Here is an example using Proxy_ticket.originate and the type unforged_ticket :

1. import the module above as Proxy_ticket
2. define a contract main potentially holding a ticket of bytes in its storage. The contract will just reads the ticket in its storage if present. Note that we define two version of the contract storage type: one for the contract and one for the storage type that we would like to manipulate in our testing logic
3. we define the mk_storage function which simply wraps a ticket into an option type
4. we define the ticket information for a ticket of value 0x0202 and an amount of 15
5. we call originate and retrieve the address of the newly originated contract
6. we use the address to fetch the current contract storage using Test.get_storage_of_address and decompile it as a human_storage
7. we read the content of the ticket and perform a series of assertions

type storage = option< ticket<bytes> >

type unforged_storage = option< unforged_ticket<bytes> >

const main = (_p: unit, s: storage) : [ list<operation> , storage] => {

let x =

match (s) {

when(Some(ticket)): ((ticket: ticket<bytes>) => {

let [_v , t] = Tezos.read_ticket (ticket) ;

return Some (t)

})(ticket);

when(None()): None()

};

return [list ([]), x]

};

const test_originate_contract = do {

const mk_storage = (t:ticket<bytes>) : storage => { return (Some (t)) } ;

let ticket_info = [0x0202, 15n];

let addr = Test.Proxy_ticket.originate (ticket_info, mk_storage, main) ;

let unforged_storage = (Test.Proxy_ticket.get_storage (addr) as unforged_storage) ;

/* the ticket 'unforged_storage' can be manipulated freely without caring about ticket linearity */

match (unforged_storage) {

when(Some(x)): do {

Test.log (["unforged_ticket", x]) ;

let { ticketer , value , amount } = x ;

assert (value == ticket_info[0]) ;

assert (amount == ticket_info[1]) ;

return unit

};

when(None()): failwith ("impossible")

}

};

result:

("unforged_ticket" , {amount = 15n ; ticketer = KT1Qp8u3v4seQHPYfpSw6eWvPG8CojH3m18G ; value = 0x0202})

Everything at the top-level was executed.

- test_originate_contract exited with value ().