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TokenΒΆ

Welcome to our guide on launching a token using the Koinos Contract Standard (KCS-1) for tokens and the AssemblyScript SDK for Koinos. In this tutorial, we'll walk you through the process of creating and deploying your own token on the Koinos blockchain. Whether you're a seasoned developer or new to blockchain development, this step-by-step guide will provide you with the knowledge and tools necessary to bring your token project to life. Let's dive in and explore the exciting world of token creation on Koinos!

Before starting, ensure that you have already set up your Koinos AssemblyScript SDK environment by following this guide.

Note

The KCS-1 token may not be compatible with certain dApps such as KoinDX. You should understand the requirements of your token before adhering to any particular standard. Visit the Koinos Contract Standards repository for more information.

The KCS-1 standard is insecure. The security is improved by KCS-3 and KCS-4. A more detailed description of the vulnerability can be found here.


Setting up the projectΒΆ

Let's begin by creating a boilerplate smart contract project using the Koinos AssemblyScript SDK.

koinos-sdk-as-cli create token
Generating contract at "/home/$USER/Workspace/token" ...

Contract successfully generated!

You're all set! Run the following set of commands to verify that the generated contract is correctly setup:

  cd /home/$USER/Workspace/token && yarn install && yarn build:debug && yarn test

Change your directory to the project directory and install dependencies.

cd token
yarn install

yarn install v1.22.19
warning ../../../../../package.json: No license field
info No lockfile found.
[1/4] πŸ”  Resolving packages...
warning @koinos/sdk-as > @koinos/mock-vm > multibase@4.0.6: This module has been superseded by the multiformats module
warning @koinos/sdk-as > @koinos/mock-vm > somap > npm > @npmcli/ci-detect@2.0.0: this package has been deprecated, use `ci-info` instead
warning @koinos/sdk-as > @koinos/mock-vm > somap > npm > libnpmexec > @npmcli/ci-detect@2.0.0: this package has been deprecated, use `ci-info` instead
warning @koinos/sdk-as > @koinos/mock-vm > somap > npm > readdir-scoped-modules@1.1.0: This functionality has been moved to @npmcli/fs
warning @koinos/sdk-as > @koinos/mock-vm > somap > npm > @npmcli/arborist > readdir-scoped-modules@1.1.0: This functionality has been moved to @npmcli/fs
warning @koinos/sdk-as > @koinos/mock-vm > somap > npm > @npmcli/arborist > @npmcli/move-file@2.0.1: This functionality has been moved to @npmcli/fs
warning @koinos/sdk-as > @koinos/mock-vm > somap > npm > cacache > @npmcli/move-file@2.0.1: This functionality has been moved to @npmcli/fs
warning @koinos/sdk-as > @koinos/mock-vm > somap > npm > readdir-scoped-modules > debuglog@1.0.1: Package no longer supported. Contact Support at https://www.npmjs.com/support for more info.
warning local-koinos > koilib > multibase@4.0.6: This module has been superseded by the multiformats module
[2/4] 🚚  Fetching packages...
[3/4] πŸ”—  Linking dependencies...
warning "@koinos/sdk-as > @as-covers/core > @as-covers/transform > visitor-as@0.6.0" has incorrect peer dependency "assemblyscript@^0.18.31".
warning " > ts-node@10.9.2" has unmet peer dependency "@types/node@*".
warning Workspaces can only be enabled in private projects.
[4/4] πŸ”¨  Building fresh packages...
success Saved lockfile.
✨  Done in 12.96s.

Defining methods and dataΒΆ

Building a contract will usually consist of behaviors and data. The behavior is defined by the smart contract. But the data is defined by Protobuf. We generate data structures with Protobuf so that the smart contract can easily integrate with other Koinos tools. We have defined the arguments and results we will use in our calculator. We use the *_arguments convention for contract function arguments and *_result for contract function results.

Let's begin by defining our entry point arguments and results.

vi assembly/proto/token.proto

Currently, the token.proto file contains the following boilerplate code:

assembly/proto/token.proto
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syntax = "proto3";

package token;

// @description Says Hello!
// @read-only true
message hello_arguments {
  string name = 1;
}

message hello_result {
  string value = 1;
}

We can remove the boilerplate code and replace it with our token arguments and results.

assembly/proto/token.proto
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syntax = "proto3";

package token;

import "koinos/options.proto";

message empty_message {}

// @description Returns the token's name
// @read-only true
message name_arguments {}

message name_result {
   string value = 1;
}

// @description Returns the token's symbol
// @read-only true
message symbol_arguments {}

message symbol_result {
   string value = 1;
}

// @description Returns the token's decimals precision
// @read-only true
message decimals_arguments {}

message decimals_result {
   uint32 value = 1;
}

// @description Returns the token's total supply
// @read-only true
message total_supply_arguments {}

message total_supply_result {
   uint64 value = 1 [jstype = JS_STRING];
}

// @description Returns the token's max supply
// @read-only true
message max_supply_arguments {}

message max_supply_result {
   uint64 value = 1 [jstype = JS_STRING];
}

// @description Checks the balance at an address
// @read-only true
message balance_of_arguments {
   bytes owner = 1 [(koinos.btype) = ADDRESS];
}

message balance_of_result {
   uint64 value = 1 [jstype = JS_STRING];
}

// @description Transfers the token
// @read-only false
// @result empty_message
message transfer_arguments {
   bytes from = 1 [(koinos.btype) = ADDRESS];
   bytes to = 2 [(koinos.btype) = ADDRESS];
   uint64 value = 3 [jstype = JS_STRING];
}

// @description Mints the token
// @read-only false
// @result empty_message
message mint_arguments {
   bytes to = 1 [(koinos.btype) = ADDRESS];
   uint64 value = 2 [jstype = JS_STRING];
}

// @description Burns the token
// @read-only false
// @result empty_message
message burn_arguments {
   bytes from = 1 [(koinos.btype) = ADDRESS];
   uint64 value = 2 [jstype = JS_STRING];
}

message balance_object {
   uint64 value = 1 [jstype = JS_STRING];
}

message mint_event {
   bytes to = 1 [(koinos.btype) = ADDRESS];
   uint64 value = 2 [jstype = JS_STRING];
}

message burn_event {
   bytes from = 1 [(koinos.btype) = ADDRESS];
   uint64 value = 2 [jstype = JS_STRING];
}

message transfer_event {
   bytes from = 1 [(koinos.btype) = ADDRESS];
   bytes to = 2 [(koinos.btype) = ADDRESS];
   uint64 value = 3 [jstype = JS_STRING];
}
Now that we have our Protobuf definition, let's generate the derived AssemblyScript code.
koinos-sdk-as-cli generate-contract-proto

Generating Contract AS proto files...
yarn protoc --plugin=protoc-gen-as=./node_modules/.bin/as-proto-gen --as_out=. assembly/proto/*.proto
yarn run v1.22.19
warning ../../../../../package.json: No license field
$ ../token-tutorial/token/node_modules/.bin/protoc --plugin=protoc-gen-as=./node_modules/.bin/as-proto-gen --as_out=. assembly/proto/token.proto
Done in 0.78s.
Note that after executing this command, the file assembly/proto/token.ts was automatically generated and contains code that will assist us in serializing and deserializing data in and out of the KVM.


The implementationΒΆ

Now, we have defined the data in which arguments come into our contract and also the data which is returned by our contract. All we need now is our implementation.

Let's use the tools to automatically generate the boilerplate implementation.

koinos-sdk-as-cli generate-contract-as token.proto

Generating boilerplate.ts and index.ts files...
yarn protoc --plugin=protoc-gen-as=./node_modules/.bin/koinos-as-gen --as_out=assembly/ assembly/proto/token.proto
yarn run v1.22.19
warning ../../../../../package.json: No license field
$ /Users/$USER/Workspace/token/token/node_modules/.bin/protoc --plugin=protoc-gen-as=./node_modules/.bin/koinos-as-gen --as_out=assembly/ assembly/proto/token.proto
Done in 1.31s.

After invoking this command, we have two newly generated files. The first is assembly/index.ts which is the first location our smart contract codes begin executing. This file acts as a router to call the appropriate method on our class because of how the smart contract was invoked.

The second file that was generated is assembly/Token.boilerplate.ts. This is where our implementation lives. We should rename this file to Token.ts and begin our implementation.

rm assembly/Token.ts
mv assembly/Token.boilerplate.ts assembly/Token.ts
vi assembly/Token.ts

Let's open our implementation file and write logic to add our token's functionality.

assembly/Token.ts
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import {
  Arrays,
  Protobuf,
  System,
  SafeMath,
  authority,
  error,
} from "@koinos/sdk-as";
import { token } from "./proto/token";
import { SupplyStorage } from "./state/SupplyStorage";
import { BalancesStorage } from "./state/BalancesStorage";

export class Token {
  // SETTINGS BEGIN
  _name: string = "[token name]";
  _symbol: string = "[token symbol]";
  _decimals: u32 = 8;

  // set _maxSupply to zero if there is no max supply
  // if set to zero, the supply would still be limited by how many tokens can fit in a u64 (u64.MAX_VALUE)
  _maxSupply: u64 = 0;

  // SETTINGS END

  _contractId: Uint8Array = System.getContractId();
  _supplyStorage: SupplyStorage = new SupplyStorage(this._contractId);
  _balancesStorage: BalancesStorage = new BalancesStorage(this._contractId);

  name(args: token.name_arguments): token.name_result {
    return new token.name_result(this._name);
  }

  symbol(args: token.symbol_arguments): token.symbol_result {
    return new token.symbol_result(this._symbol);
  }

  decimals(args: token.decimals_arguments): token.decimals_result {
    return new token.decimals_result(this._decimals);
  }

  total_supply(args: token.total_supply_arguments): token.total_supply_result {
    const supply = this._supplyStorage.get()!;

    const res = new token.total_supply_result();
    res.value = supply.value;

    return res;
  }

  max_supply(args: token.max_supply_arguments): token.max_supply_result {
    return new token.max_supply_result(this._maxSupply);
  }

  balance_of(args: token.balance_of_arguments): token.balance_of_result {
    const owner = args.owner;

    const balanceObj = this._balancesStorage.get(owner!)!;

    const res = new token.balance_of_result();
    res.value = balanceObj.value;

    return res;
  }

  transfer(args: token.transfer_arguments): token.empty_message {
    System.require(args.from, "Missing 'from' field");
    System.require(args.to, "Missing 'to' field");
    const from = args.from!;
    const to = args.to!;
    const value = args.value;

    System.require(!Arrays.equal(from, to), "Cannot transfer to self");

    System.require(
      Arrays.equal(System.getCaller().caller, from) ||
        System.checkAuthority(
          authority.authorization_type.contract_call,
          from,
          System.getArguments().args
        ),
      "'from' has not authorized transfer",
      error.error_code.authorization_failure
    );

    const fromBalance = this._balancesStorage.get(from)!;

    System.require(
      fromBalance.value >= value,
      "'from' has insufficient balance"
    );

    const toBalance = this._balancesStorage.get(to)!;

    // the balances cannot hold more than the supply, so we don't check for overflow/underflow
    fromBalance.value -= value;
    toBalance.value += value;

    this._balancesStorage.put(from, fromBalance);
    this._balancesStorage.put(to, toBalance);

    const transferEvent = new token.transfer_event(from, to, value);
    const impacted = [to, from];

    System.event(
      "koinos.contracts.token.transfer_event",
      Protobuf.encode(transferEvent, token.transfer_event.encode),
      impacted
    );

    return new token.empty_message();
  }

  mint(args: token.mint_arguments): token.empty_message {
    System.require(args.to, "Missing 'to' field");
    const to = args.to!;
    const value = args.value;

    System.requireAuthority(
      authority.authorization_type.contract_call,
      this._contractId
    );

    const supply = this._supplyStorage.get()!;

    const newSupply = SafeMath.tryAdd(supply.value, value);

    System.require(!newSupply.error, "Mint would overflow supply");

    System.require(
      this._maxSupply == 0 || newSupply.value <= this._maxSupply,
      "Mint would overflow max supply"
    );

    const toBalance = this._balancesStorage.get(to)!;
    toBalance.value += value;

    supply.value = newSupply.value;

    this._supplyStorage.put(supply);
    this._balancesStorage.put(to, toBalance);

    const mintEvent = new token.mint_event(to, value);
    const impacted = [to];

    System.event(
      "koinos.contracts.token.mint_event",
      Protobuf.encode(mintEvent, token.mint_event.encode),
      impacted
    );

    return new token.empty_message();
  }

  burn(args: token.burn_arguments): token.empty_message {
    System.require(args.from, "Missing 'from' field");
    const from = args.from!;
    const value = args.value;

    System.require(
      Arrays.equal(System.getCaller().caller, from) ||
        System.checkAuthority(
          authority.authorization_type.contract_call,
          from,
          System.getArguments().args
        ),
      "'from' has not authorized transfer",
      error.error_code.authorization_failure
    );

    const fromBalance = this._balancesStorage.get(from)!;

    System.require(
      fromBalance.value >= value,
      "'from' has insufficient balance"
    );

    const supply = this._supplyStorage.get()!;

    const newSupply = SafeMath.sub(supply.value, value);

    supply.value = newSupply;
    fromBalance.value -= value;

    this._supplyStorage.put(supply);
    this._balancesStorage.put(from, fromBalance);

    const burnEvent = new token.burn_event(from, value);
    const impacted = [from];

    System.event(
      "koinos.contracts.token.burn_event",
      Protobuf.encode(burnEvent, token.burn_event.encode),
      impacted
    );

    return new token.empty_message();
  }
}

We have to add assembly/state directory where we define our storage.

assembly/state
mkdir assembly/state && touch assembly/state/BalancesStorage.ts assembly/state/SpaceIds.ts assembly/state/SupplyStorage.ts

Create the above files and add this code to each:

assembly/state/BalancesStorage.ts
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import { Storage } from '@koinos/sdk-as';
import { token } from '../proto/token';
import { BALANCE_SPACE_ID } from './SpaceIds';

export class BalancesStorage extends Storage.Map<Uint8Array, token.balance_object> {
  constructor(contractId: Uint8Array) {
    super(
      contractId,
      BALANCE_SPACE_ID,
      token.balance_object.decode,
      token.balance_object.encode,
      // default balance is 0
      () => new token.balance_object()
    );
  }
}
assembly/state/SpaceIds.ts
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export const SUPPLY_SPACE_ID = 0;
export const BALANCE_SPACE_ID = 1;
assembly/state/SupplyStorage.ts
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import { Storage } from '@koinos/sdk-as';
import { token } from '../proto/token';
import { SUPPLY_SPACE_ID } from './SpaceIds';

export class SupplyStorage extends Storage.Obj<token.balance_object> {
  constructor(contractId: Uint8Array) {
    super(
      contractId,
      SUPPLY_SPACE_ID,
      token.balance_object.decode,
      token.balance_object.encode,
      // total supply is 0 by default
      () => new token.balance_object()
    );
  }
}

Time for testsΒΆ

Let's open up assembly/__tests__/Calculator.spec.ts and write some tests.

assembly/__tests__/Token.spec.ts
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import {
  Base58,
  MockVM,
  Arrays,
  Protobuf,
  authority,
  chain,
} from "@koinos/sdk-as";
import { Token } from "../Token";
import { token } from "../proto/token";

const CONTRACT_ID = Base58.decode("1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqe");
const MOCK_ACCT1 = Base58.decode("1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqG");
const MOCK_ACCT2 = Base58.decode("1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqK");

describe("token", () => {
  beforeEach(() => {
    MockVM.reset();
    MockVM.setContractId(CONTRACT_ID);
    MockVM.setCaller(
      new chain.caller_data(new Uint8Array(0), chain.privilege.user_mode)
    );
  });

  it("should get the name", () => {
    const tkn = new Token();

    const args = new token.name_arguments();
    const res = tkn.name(args);

    expect(res.value).toBe("[token name]");
  });

  it("should get the symbol", () => {
    const tkn = new Token();

    const args = new token.symbol_arguments();
    const res = tkn.symbol(args);

    expect(res.value).toBe("[token symbol]");
  });

  it("should get the decimals", () => {
    const tkn = new Token();

    const args = new token.decimals_arguments();
    const res = tkn.decimals(args);

    expect(res.value).toBe(8);
  });

  it("should get the max supply", () => {
    const tkn = new Token();

    const args = new token.max_supply_arguments();
    const res = tkn.max_supply(args);

    expect(res.value).toBe(0);
  });

  it("should/not burn tokens", () => {
    const tkn = new Token();

    MockVM.setContractArguments(new Uint8Array(0));
    MockVM.setEntryPoint(1);

    // set contract_call authority for CONTRACT_ID to true so that we can mint tokens
    let auth = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      CONTRACT_ID,
      true
    );
    MockVM.setAuthorities([auth]);

    // check total supply
    const totalSupplyArgs = new token.total_supply_arguments();
    let totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(0);

    // mint tokens
    const mintArgs = new token.mint_arguments(MOCK_ACCT1, 123);
    tkn.mint(mintArgs);

    auth = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      MOCK_ACCT1,
      true
    );
    MockVM.setAuthorities([auth]);

    // burn tokens
    let burnArgs = new token.burn_arguments(MOCK_ACCT1, 10);
    tkn.burn(burnArgs);

    // check events
    const events = MockVM.getEvents();
    expect(events.length).toBe(2);
    expect(events[0].name).toBe("koinos.contracts.token.mint_event");
    expect(events[0].impacted.length).toBe(1);
    expect(Arrays.equal(events[0].impacted[0], MOCK_ACCT1)).toBe(true);
    expect(events[1].name).toBe("koinos.contracts.token.burn_event");
    expect(events[1].impacted.length).toBe(1);
    expect(Arrays.equal(events[1].impacted[0], MOCK_ACCT1)).toBe(true);

    const burnEvent = Protobuf.decode<token.burn_event>(
      events[1].data!,
      token.burn_event.decode
    );
    expect(Arrays.equal(burnEvent.from, MOCK_ACCT1)).toBe(true);
    expect(burnEvent.value).toBe(10);

    // check balance
    let balanceArgs = new token.balance_of_arguments(MOCK_ACCT1);
    let balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(113);

    // check total supply
    totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(113);

    // save the MockVM state because the burn is going to revert the transaction
    MockVM.commitTransaction();

    // does not burn tokens
    expect(() => {
      const tkn = new Token();
      const burnArgs = new token.burn_arguments(MOCK_ACCT1, 200);
      tkn.burn(burnArgs);
    }).toThrow();

    // check error message
    expect(MockVM.getErrorMessage()).toStrictEqual(
      "'from' has insufficient balance"
    );

    MockVM.setAuthorities([]);

    // save the MockVM state because the burn is going to revert the transaction
    MockVM.commitTransaction();

    expect(() => {
      // try to burn tokens
      const tkn = new Token();
      const burnArgs = new token.burn_arguments(MOCK_ACCT1, 123);
      tkn.burn(burnArgs);
    }).toThrow();

    // check balance
    balanceArgs = new token.balance_of_arguments(MOCK_ACCT1);
    balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(113);

    // check total supply
    totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(113);
  });

  it("should mint tokens", () => {
    const tkn = new Token();

    // set contract_call authority for CONTRACT_ID to true so that we can mint tokens
    const auth = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      CONTRACT_ID,
      true
    );
    MockVM.setAuthorities([auth]);

    // check total supply
    const totalSupplyArgs = new token.total_supply_arguments();
    let totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(0);

    // mint tokens
    const mintArgs = new token.mint_arguments(MOCK_ACCT1, 123);
    tkn.mint(mintArgs);

    // check events
    const events = MockVM.getEvents();
    expect(events.length).toBe(1);
    expect(events[0].name).toBe("koinos.contracts.token.mint_event");
    expect(events[0].impacted.length).toBe(1);
    expect(Arrays.equal(events[0].impacted[0], MOCK_ACCT1)).toBe(true);

    const mintEvent = Protobuf.decode<token.mint_event>(
      events[0].data!,
      token.mint_event.decode
    );
    expect(Arrays.equal(mintEvent.to, MOCK_ACCT1)).toBe(true);
    expect(mintEvent.value).toBe(123);

    // check balance
    const balanceArgs = new token.balance_of_arguments(MOCK_ACCT1);
    const balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(123);

    // check total supply
    totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(123);
  });

  it("should not mint tokens if not contract account", () => {
    const tkn = new Token();

    // set contract_call authority for MOCK_ACCT1 to true so that we cannot mint tokens
    const auth = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      MOCK_ACCT1,
      true
    );
    MockVM.setAuthorities([auth]);

    // check total supply
    const totalSupplyArgs = new token.total_supply_arguments();
    let totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(0);

    // check balance
    const balanceArgs = new token.balance_of_arguments(MOCK_ACCT1);
    let balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(0);

    // save the MockVM state because the mint is going to revert the transaction
    MockVM.commitTransaction();

    expect(() => {
      // try to mint tokens
      const tkn = new Token();
      const mintArgs = new token.mint_arguments(MOCK_ACCT2, 123);
      tkn.mint(mintArgs);
    }).toThrow();

    // check balance
    balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(0);

    // check total supply
    totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(0);
  });

  it("should not mint tokens if new total supply overflows", () => {
    const tkn = new Token();

    // set contract_call authority for CONTRACT_ID to true so that we can mint tokens
    const auth = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      CONTRACT_ID,
      true
    );
    MockVM.setAuthorities([auth]);

    let mintArgs = new token.mint_arguments(MOCK_ACCT2, 123);
    tkn.mint(mintArgs);

    // check total supply
    let totalSupplyArgs = new token.total_supply_arguments();
    let totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(123);

    // save the MockVM state because the mint is going to revert the transaction
    MockVM.commitTransaction();

    expect(() => {
      // try to mint tokens
      const tkn = new Token();
      const mintArgs = new token.mint_arguments(MOCK_ACCT2, u64.MAX_VALUE);
      tkn.mint(mintArgs);
    }).toThrow();

    expect(MockVM.getErrorMessage()).toStrictEqual(
      "Mint would overflow supply"
    );

    // check total supply
    totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(123);
  });

  it("should not mint tokens if new total supply overflows max supply", () => {
    const tkn = new Token();

    // set contract_call authority for CONTRACT_ID to true so that we can mint tokens
    const auth = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      CONTRACT_ID,
      true
    );
    MockVM.setAuthorities([auth]);

    let mintArgs = new token.mint_arguments(MOCK_ACCT2, 123);
    tkn.mint(mintArgs);

    // check total supply
    let totalSupplyArgs = new token.total_supply_arguments();
    let totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(123);

    // save the MockVM state because the mint is going to revert the transaction
    MockVM.commitTransaction();

    expect(() => {
      // try to mint tokens
      const tkn = new Token();
      tkn._maxSupply = 400;
      const mintArgs = new token.mint_arguments(MOCK_ACCT2, 500);
      tkn.mint(mintArgs);
    }).toThrow();

    expect(MockVM.getErrorMessage()).toStrictEqual(
      "Mint would overflow max supply"
    );

    // check total supply
    totalSupplyRes = tkn.total_supply(totalSupplyArgs);
    expect(totalSupplyRes.value).toBe(123);
  });

  it("should transfer tokens", () => {
    const tkn = new Token();

    MockVM.setContractArguments(new Uint8Array(0));
    MockVM.setEntryPoint(1);

    // set contract_call authority for CONTRACT_ID to true so that we can mint tokens
    const authContractId = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      CONTRACT_ID,
      true
    );

    // set contract_call authority for MOCK_ACCT1 to true so that we can transfer tokens
    const authMockAcct1 = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      MOCK_ACCT1,
      true
    );
    MockVM.setAuthorities([authContractId, authMockAcct1]);

    // mint tokens
    const mintArgs = new token.mint_arguments(MOCK_ACCT1, 123);
    tkn.mint(mintArgs);

    // transfer tokens
    const transferArgs = new token.transfer_arguments(
      MOCK_ACCT1,
      MOCK_ACCT2,
      10
    );
    tkn.transfer(transferArgs);

    // check balances
    let balanceArgs = new token.balance_of_arguments(MOCK_ACCT1);
    let balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(113);

    balanceArgs = new token.balance_of_arguments(MOCK_ACCT2);
    balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(10);

    // check events
    const events = MockVM.getEvents();
    // 2 events, 1st one is the mint event, the second one is the transfer event
    expect(events.length).toBe(2);
    expect(events[1].name).toBe("koinos.contracts.token.transfer_event");
    expect(events[1].impacted.length).toBe(2);
    expect(Arrays.equal(events[1].impacted[0], MOCK_ACCT2)).toBe(true);
    expect(Arrays.equal(events[1].impacted[1], MOCK_ACCT1)).toBe(true);

    const transferEvent = Protobuf.decode<token.transfer_event>(
      events[1].data!,
      token.transfer_event.decode
    );
    expect(Arrays.equal(transferEvent.from, MOCK_ACCT1)).toBe(true);
    expect(Arrays.equal(transferEvent.to, MOCK_ACCT2)).toBe(true);
    expect(transferEvent.value).toBe(10);
  });

  it("should not transfer tokens without the proper authorizations", () => {
    MockVM.setContractArguments(new Uint8Array(0));
    MockVM.setEntryPoint(1);
    const tkn = new Token();

    // set contract_call authority for CONTRACT_ID to true so that we can mint tokens
    const authContractId = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      CONTRACT_ID,
      true
    );
    // do not set authority for MOCK_ACCT1
    MockVM.setAuthorities([authContractId]);

    // mint tokens
    const mintArgs = new token.mint_arguments(MOCK_ACCT1, 123);
    tkn.mint(mintArgs);

    // save the MockVM state because the transfer is going to revert the transaction
    MockVM.commitTransaction();

    expect(() => {
      // try to transfer tokens without the proper authorizations for MOCK_ACCT1
      const tkn = new Token();
      const transferArgs = new token.transfer_arguments(
        MOCK_ACCT1,
        MOCK_ACCT2,
        10
      );
      tkn.transfer(transferArgs);
    }).toThrow();

    expect(MockVM.getErrorMessage()).toStrictEqual(
      "'from' has not authorized transfer"
    );

    // check balances
    let balanceArgs = new token.balance_of_arguments(MOCK_ACCT1);
    let balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(123);

    balanceArgs = new token.balance_of_arguments(MOCK_ACCT2);
    balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(0);
  });

  it("should not transfer tokens to self", () => {
    const tkn = new Token();

    // set contract_call authority for CONTRACT_ID to true so that we can mint tokens
    const authContractId = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      CONTRACT_ID,
      true
    );

    // set contract_call authority for MOCK_ACCT1 to true so that we can transfer tokens
    const authMockAcct1 = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      MOCK_ACCT1,
      true
    );
    MockVM.setAuthorities([authContractId, authMockAcct1]);

    // mint tokens
    const mintArgs = new token.mint_arguments(MOCK_ACCT1, 123);
    tkn.mint(mintArgs);

    // save the MockVM state because the transfer is going to revert the transaction
    MockVM.commitTransaction();

    expect(() => {
      // try to transfer tokens
      const tkn = new Token();
      const transferArgs = new token.transfer_arguments(
        MOCK_ACCT1,
        MOCK_ACCT1,
        10
      );
      tkn.transfer(transferArgs);
    }).toThrow();

    expect(MockVM.getErrorMessage()).toStrictEqual("Cannot transfer to self");

    // check balances
    let balanceArgs = new token.balance_of_arguments(MOCK_ACCT1);
    let balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(123);
  });

  it("should not transfer if insufficient balance", () => {
    MockVM.setContractArguments(new Uint8Array(0));
    MockVM.setEntryPoint(1);
    const tkn = new Token();

    // set contract_call authority for CONTRACT_ID to true so that we can mint tokens
    const authContractId = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      CONTRACT_ID,
      true
    );

    // set contract_call authority for MOCK_ACCT1 to true so that we can transfer tokens
    const authMockAcct1 = new MockVM.MockAuthority(
      authority.authorization_type.contract_call,
      MOCK_ACCT1,
      true
    );
    MockVM.setAuthorities([authContractId, authMockAcct1]);

    // mint tokens
    const mintArgs = new token.mint_arguments(MOCK_ACCT1, 123);
    tkn.mint(mintArgs);

    // save the MockVM state because the transfer is going to revert the transaction
    MockVM.commitTransaction();

    expect(() => {
      // try to transfer tokens
      const tkn = new Token();
      const transferArgs = new token.transfer_arguments(
        MOCK_ACCT1,
        MOCK_ACCT2,
        456
      );
      tkn.transfer(transferArgs);
    }).toThrow();

    expect(MockVM.getErrorMessage()).toStrictEqual(
      "'from' has insufficient balance"
    );

    // check balances
    let balanceArgs = new token.balance_of_arguments(MOCK_ACCT1);
    let balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(123);

    balanceArgs = new token.balance_of_arguments(MOCK_ACCT2);
    balanceRes = tkn.balance_of(balanceArgs);
    expect(balanceRes.value).toBe(0);
  });
});

Run the build debug command

koinos-sdk-as-cli build debug 0
Compiling index.ts...
node ./node_modules/assemblyscript/bin/asc assembly/index.ts --target debug --use abort= --use BUILD_FOR_TESTING=0 --disable sign-extension --config asconfig.json

And now let's run the tests

koinos-sdk-as-cli run-tests
Running tests...
yarn asp --verbose --config as-pect.config.js
yarn run v1.22.19
warning ../../../../../package.json: No license field
$ /path/to/token/node_modules/.bin/asp --verbose --config as-pect.config.js
       ___   _____                       __
      /   | / ___/      ____  ___  _____/ /_
     / /| | \__ \______/ __ \/ _ \/ ___/ __/
    / ___ |___/ /_____/ /_/ /  __/ /__/ /_
   /_/  |_/____/     / .___/\___/\___/\__/
                    /_/

⚑AS-pect⚑ Test suite runner [6.2.4]

[Log] Loading asc compiler
Assemblyscript Folder:assemblyscript
[Log] Compiler loaded in 165.113ms.
[Log] Using configuration /path/to/token/as-pect.config.js
[Log] Using VerboseReporter
[Log] Including files: assembly/__tests__/**/*.spec.ts
[Log] Running tests that match: (:?)
[Log] Running groups that match: (:?)
[Log] Effective command line args:
  [TestFile.ts] node_modules/@as-pect/assembly/assembly/index.ts --runtime incremental --debug --binaryFile output.wasm --explicitStart --use ASC_RTRACE=1 --exportTable --importMemory --transform /path/to/token/node_modules/@as-covers/transform/lib/index.js,/path/to/token/node_modules/@as-pect/core/lib/transform/index.js --lib node_modules/@as-covers/assembly/index.ts

[Describe]: token

 [Success]: βœ” should get the name RTrace: +26
 [Success]: βœ” should get the symbol RTrace: +26
 [Success]: βœ” should get the decimals RTrace: +22
 [Success]: βœ” should get the max supply RTrace: +22
[Event] koinos.contracts.token.mint_event / [ '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqG' ] / ChkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc3EHs=
[Event] koinos.contracts.token.burn_event / [ '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqG' ] / ChkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc3EAo=
[Contract Exit] 'from' has insufficient balance
[Contract Exit] 'from' has not authorized transfer
 [Success]: βœ” should/not burn tokens RTrace: +656
[Event] koinos.contracts.token.mint_event / [ '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqG' ] / ChkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc3EHs=
 [Success]: βœ” should mint tokens RTrace: +281
[Contract Exit] account '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqe' authorization failed
 [Success]: βœ” should not mint tokens if not contract account RTrace: +207
[Event] koinos.contracts.token.mint_event / [ '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqK' ] / ChkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc6EHs=
[Contract Exit] Mint would overflow supply
 [Success]: βœ” should not mint tokens if new total supply overflows RTrace: +338
[Event] koinos.contracts.token.mint_event / [ '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqK' ] / ChkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc6EHs=
[Contract Exit] Mint would overflow max supply
 [Success]: βœ” should not mint tokens if new total supply overflows max supply RTrace: +338
[Event] koinos.contracts.token.mint_event / [ '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqG' ] / ChkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc3EHs=
[Event] koinos.contracts.token.transfer_event / [
  '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqK',
  '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqG'
] / ChkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc3EhkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc6GAo=
 [Success]: βœ” should transfer tokens RTrace: +391
[Event] koinos.contracts.token.mint_event / [ '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqG' ] / ChkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc3EHs=
[Contract Exit] 'from' has not authorized transfer
 [Success]: βœ” should not transfer tokens without the proper authorizations RTrace: +295
[Event] koinos.contracts.token.mint_event / [ '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqG' ] / ChkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc3EHs=
[Contract Exit] Cannot transfer to self
 [Success]: βœ” should not transfer tokens to self RTrace: +234
[Event] koinos.contracts.token.mint_event / [ '1DQzuCcTKacbs9GGScRTU1Hc8BsyARTPqG' ] / ChkAiCtotTmdMTyQZ/OEFgfmKMEtVCA8jEc3EHs=
[Contract Exit] 'from' has insufficient balance
 [Success]: βœ” should not transfer if insufficient balance RTrace: +307

    [File]: assembly/__tests__/Token.spec.ts
  [Groups]: 2 pass, 2 total
  [Result]: βœ” PASS
[Snapshot]: 0 total, 0 added, 0 removed, 0 different
 [Summary]: 13 pass,  0 fail, 13 total
    [Time]: 131.568ms

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  [Result]: βœ” PASS
   [Files]: 1 total
  [Groups]: 2 count, 2 pass
   [Tests]: 13 pass, 0 fail, 13 total
    [Time]: 4894.475ms
β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚ File              β”‚ Total β”‚ Block β”‚ Func β”‚ Expr β”‚ Uncovered β”‚
β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
β”‚ assembly/Token.ts β”‚ 100%  β”‚ 100%  β”‚ 100% β”‚ 100% β”‚           β”‚
β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
β”‚ total             β”‚ 100%  β”‚ 100%  β”‚ 100% β”‚ 100% β”‚           β”‚
β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

Done in 5.19s.

Customizing the tokenΒΆ

Let's customize the specifics of our token project by modifying ./assembly/Token.ts. Define the following:

  • _name: The name of your token

  • _symbol: The symbol for your token

  • _decimals: The decimal places for your token

Let's change the default values to the name and symbol of our token.

assembly/Token.ts
 9
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11
12
13
14
15
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18
19
20
21
import { token } from "./proto/token";
import { SupplyStorage } from "./state/SupplyStorage";
import { BalancesStorage } from "./state/BalancesStorage";

export class Token {
  // SETTINGS BEGIN
  _name: string = "My Token Name";
  _symbol: string = "MTN";
  _decimals: u32 = 8;

  // set _maxSupply to zero if there is no max supply
  // if set to zero, the supply would still be limited by how many tokens can fit in a u64 (u64.MAX_VALUE)
  _maxSupply: u64 = 0;

In the highlighted lines we changed the [token name] variable to My Token Name and the symbol variable to MTN.

Keep in mind that since this token name and symbol have already been minted to the testnet you should replace your own name and symbol with the ones used in this guide.

Let's run the tests again and see what happens.

koinos-sdk-as-cli run-tests
[Describe]: token

    [Fail]: βœ– should get the name
  [Actual]: "My Token Name"
[Expected]: "[token name]"
   [Stack]: RuntimeError: unreachable
            at node_modules/@as-pect/assembly/assembly/internal/assert/assert (wasm://wasm/00070616:wasm-function[64]:0x30c8)
            at node_modules/@as-pect/assembly/assembly/internal/Expectation/Expectation<~lib/string/String|null>#toBe (wasm://wasm/00070616:wasm-function[129]:0xb1bb)
            at start:assembly/__tests__/Token.spec~anonymous|0~anonymous|1 (wasm://wasm/00070616:wasm-function[130]:0xb392)
            at export:node_modules/@as-pect/assembly/assembly/internal/call/__call (wasm://wasm/00070616:wasm-function[236]:0x14f37)
    [Fail]: βœ– should get the symbol
  [Actual]: "MTN"
[Expected]: "[token symbol]"
   [Stack]: RuntimeError: unreachable
            at node_modules/@as-pect/assembly/assembly/internal/assert/assert (wasm://wasm/00070616:wasm-function[64]:0x30c8)
            at node_modules/@as-pect/assembly/assembly/internal/Expectation/Expectation<~lib/string/String|null>#toBe (wasm://wasm/00070616:wasm-function[129]:0xb1bb)
            at start:assembly/__tests__/Token.spec~anonymous|0~anonymous|2 (wasm://wasm/00070616:wasm-function[131]:0xb557)
            at export:node_modules/@as-pect/assembly/assembly/internal/call/__call (wasm://wasm/00070616:wasm-function[236]:0x14f37)

We now get these errors because we haven't updated the tests to reflect the changes we made to the token. Let's update the tests to reflect the changes we made to the token.

In the following code snippets the highlighted lines were added.

assembly/__tests__/Token.spec.ts
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 it("should get the name", () => {
    const tkn = new Token();

    const args = new token.name_arguments();
    const res = tkn.name(args);

    expect(res.value).toBe("My Token Name");
  });

  it("should get the symbol", () => {
    const tkn = new Token();

    const args = new token.symbol_arguments();
    const res = tkn.symbol(args);

    expect(res.value).toBe("MTN");
  });

If we run the tests again we should now have an all green 100% pass.

koinos-sdk-as-cli run-tests
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  [Result]: βœ” PASS
   [Files]: 1 total
  [Groups]: 2 count, 2 pass
   [Tests]: 13 pass, 0 fail, 13 total
    [Time]: 4944.864ms
β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚ File              β”‚ Total β”‚ Block β”‚ Func β”‚ Expr β”‚ Uncovered β”‚
β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
β”‚ assembly/Token.ts β”‚ 100%  β”‚ 100%  β”‚ 100% β”‚ 100% β”‚           β”‚
β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
β”‚ total             β”‚ 100%  β”‚ 100%  β”‚ 100% β”‚ 100% β”‚           β”‚
β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

Compiling the contractΒΆ

We made all the necessary modifications and our tests are passing, we are now ready to build the release version of the token contract.

Let's run the build script for release.

koinos-sdk-as-cli build-all release 0 token.proto
Compiling index.ts...
node ./node_modules/assemblyscript/bin/asc assembly/index.ts --target release --use abort= --use BUILD_FOR_TESTING=0 --disable sign-extension --config asconfig.json
❯ koinos-sdk-as-cli build-all release 0 token.proto
Generating ABI file...
 yarn protoc --plugin=protoc-gen-abi=./node_modules/.bin/koinos-abi-proto-gen --abi_out=abi/ assembly/proto/token.proto
yarn run v1.22.19
warning ../../../../../package.json: No license field
$ /path/to/token/node_modules/.bin/protoc --plugin=protoc-gen-abi=./node_modules/.bin/koinos-abi-proto-gen --abi_out=abi/ assembly/proto/token.proto
installing minimist@^1.2.0
installing uglify-js@^3.7.7
installing escodegen@^1.13.0
Done in 2.25s.
Generating proto files...
yarn protoc --plugin=protoc-gen-as=./node_modules/.bin/as-proto-gen --as_out=. assembly/proto/*.proto
yarn run v1.22.19
warning ../../../../../package.json: No license field
$ /path/to/token/node_modules/.bin/protoc --plugin=protoc-gen-as=./node_modules/.bin/as-proto-gen --as_out=. assembly/proto/token.proto
Done in 0.44s.
Generating boilerplate.ts and index.ts files...
yarn protoc --plugin=protoc-gen-as=./node_modules/.bin/koinos-as-gen --as_out=assembly/ assembly/proto/token.proto
yarn run v1.22.19
warning ../../../../../package.json: No license field
$ /path/to/token/node_modules/.bin/protoc --plugin=protoc-gen-as=./node_modules/.bin/koinos-as-gen --as_out=assembly/ assembly/proto/token.proto
Done in 0.35s.
Compiling index.ts...
node ./node_modules/assemblyscript/bin/asc assembly/index.ts --target release --use abort= --use BUILD_FOR_TESTING=0 --disable sign-extension --config asconfig.json

After the build completes, locate your .wasm and .abi files:

  • .wasm file: ./build/release/contract.wasm
  • .abi file: ./abi/token.abi

With these files, we can upload our contract to the blockchain by following the Deploying a contract documentation.

Minting the tokenΒΆ

Now that our contract is deployed to the testnet let's register our contract so we can mint tokens by issuing the register command register <name:contract-name> <address:address> [abi-filename:file]. Note that we are registering the address that we uploaded to (see above).

register test 163m4hKj1QHLCyHgnyNPw8TZU5ov25QGQX token.abi

We will get this response:

Contract 'test' at address 163m4hKj1QHLCyHgnyNPw8TZU5ov25QGQX registered

We will now have new commands available to us to interact with our contract.

To make sure it all worked we can try the command test.symbol

test.symbol
value:  "MTN"

We can now issue the mint command to mint our tokens. Let's create a new wallet we can mint the tokens to.

create mint_to.wallet password
Created and opened new wallet: mint_to.wallet
Address: 14xHsbnNnHVqDXaHq99A3ZEAEzQAwd9mtt

We need to switch back to our test.wallet so we can mint the tokens.

test.mint 14xHsbnNnHVqDXaHq99A3ZEAEzQAwd9mtt 100000000000000

Note

Since we are using the register command to mint the tokens, the decimals of the token are not taken into consideration. When we created out token contract we did not change the default 8 decimal places (see highlighted).

token/assembly/Token.ts
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export class Token {
  // SETTINGS BEGIN
  _name: string = "My Token Name";
  _symbol: string = "MTN";
  _decimals: u32 = 8;

  // set _maxSupply to zero if there is no max supply
  // if set to zero, the supply would still be limited by how many tokens can fit in a u64 (u64.MAX_VALUE)
  _maxSupply: u64 = 0;

We therefore need to enter the number of tokens to mint in the smallest unit of the token. In this case, we need to enter 100000000 to mint 1 token. Later, we will use the register_token command which will take the decimals into account.

We should get this response:

Calling test.mint with arguments 'to:  "14xHsbnNnHVqDXaHq99A3ZEAEzQAwd9mtt"
value:  100000000000000
'
Transaction with ID 0x1220e558d2d1d634321ce90e452d126a4b6b89723345b4fa9f936017770c0e28bc84 containing 1 operations submitted.
Mana cost: 0.03434252 (Disk: 95, Network: 284, Compute: 514975)

Transferring tokensΒΆ

Let's transfer some of the tokens we just minted to a new wallet. We can use the same contract we just registered, however the CLI provides a command, register_token that provides a cleaner interface for interacting with tokens directly.

Open the mint_to.wallet and this time register the token contract using the register_token command.

register_token mtn 163m4hKj1QHLCyHgnyNPw8TZU5ov25QGQX
Contract 'mtn' at address 163m4hKj1QHLCyHgnyNPw8TZU5ov25QGQX registered

We can now issue the mtn.transfer command and transfer some tokens.

mtn.transfer 1Npov1QbcRUuw17xoWDGKEAfk2X5hJ8ueW 0.00000001
Transferring 0.00000001 MTN to 1Npov1QbcRUuw17xoWDGKEAfk2X5hJ8ueW
Transaction with ID 0x12202aa89a221ac7be8c4cbc42ff0d4cdf653a52f7b96a5824de826947684e882c37 containing 1 operations submitted.
Mana cost: 0.03231164 (Disk: 95, Network: 308, Compute: 456741)

Note

When using the register_token command as indicated by the documentation in the Koinos CLI: Register token section, the decimals of the token are taken into consideration. As demonstrated above, we are sending 0.00000001 MTN as indicated by the 8 decimal places. If you want to use register_token with an offline wallet, you need to provide the precision and symbol manually.

register_token mtn 163m4hKj1QHLCyHgnyNPw8TZU5ov25QGQX MTN 8

Congratulations, We successfully deployed our contract to the testnet, minted a million tokens and made a transfer! We can check the block explorer and see that we now have the newly minted tokens in our wallet and that tokens were transferred from our minted wallet.