Accounting Kata

Phase 1

For this phase, we want to support a basic sub-category balances of a user's SYS token balance. For instance, one category could be "savings" and another could be "vacation". By default, all SYS tokens are categorized as a default category and this is the only category that should allow deposits and withdraws of tokens from outside parties.

This phase should be implemented with a focus on correctness and user experience. However, it is always beneficial to consider how the data model may need to change to support future enhancements and to keep track of the resources that the user will need in order to operate the contracts core feature set.

Prerequisites

This kata assumes knowledge of setting up a basic single node test net and deploying contracts to it. If those concepts need refreshment refer to the Quick Start Guide

User Stories

As a user, I can define the categories used to sub-divide my token balance.

Acceptance Criteria 1

1. A user must be able to create new categories where each category:
   is defined by a unique human readable string
   is associated with an automatically generated numeric unique ID
2. A user must be able to retrieve a listing of existing categories
   the listing must display both the ID and human readable string
   There is no restriction placed on how the listing is assembled or displayed
3. An action that attempts to duplicate a category must fail objectively
4. As a user, I can re-categorize any quantity of SYS tokens in my account from one category to another.

Acceptance Criteria 2

1. As a user i can issue an action that categorizes un-categorized or "default" tokens into a certain category bucket provided:
   that quantity of SYS tokens exists in an uncategorized or default state on the account
2. As a user i can issue an action that re-categorizes tokens from one category to another provided:
   the current category's balance is greater than or equal to the quantity of SYS tokens being re-categorized
3. A user must be able to retrieve a listing of existing category balances, including a default or un-categorized entry
   the listing must display the human readable category string
   There is no restriction placed on how the listing is assembled or displayed
4. As a user, I am protected from eosio.token::transfer actions which send more SYS tokens than my un-categorized or "default" balance

Acceptance Criteria 3

1. A user must be able to successfully transfer a quantity of SYS tokens less than or equal their uncategorized balance
2. A user must not be able to successfully transfer a quantity of SYS tokens greater than their uncategorized balance

Notes

For the purposes of this kata, we can assume that the user (and owner of the contract) is capable of covering all resource costs.

Demo:

compile:

$ eosio-cpp kata1.cpp -o kata1.wasm -abigen -I=../eosio.contracts/contracts/eosio.token/include

create account:

$ cleos create account han cats4 EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV
$ cleos set account permission cats4 active --add-code

set contract:

$ cleos set contract cats4 $(pwd) --abi kata1.abi -p cats4@active

trunsfer money to cats4 account:

$ cleos push action eosio.token transfer '[ "alice", "cats4", "25.0000 SYS", "m" ]' -p alice@active

print balance:

$ cleos -v push action cats4 printbal '[ "" ]' -p cats4@active

add new category Acceptance Criteria 1:

$ cleos -v push action cats4 addtype '[ "checking" ]' -p cats4@active

try to duplicate and there will be an error:

$ cleos -v push action cats4 addtype '[ "checking" ]' -p cats4@active

print categiries

$ cleos -v push action cats4 listtypes '[ "" ]' -p cats4@active

transfer between categories Acceptance Criteria 2:

$ cleos -v push action cats4 transfer '[ "cats4", "default", "cats4", "checking", "5.0000 SYS", "m" ]' -p cats4@active
$ cleos -v push action cats4 transfer '[ "cats4", "checking", "cats4", "default", "1.0000 SYS", "m" ]' -p cats4@active

print balance:

$ cleos -v push action cats4 printbal '[ "" ]' -p cats4@active

transfer from default account Acceptance Criteria 3:

$ cleos -v push action cats4 transfer '[ "cats4", "default", "alice", "", "5.0000 SYS", "m" ]' -p cats4@active

print balance:

$ cleos -v push action cats4 printbal '[ "" ]' -p cats4@active

trying to overdraft:

$ cleos push action eosio.token transfer '[ "cats4", "alice", "20.0000 SYS", "m" ]' -p cats4@active

See deffered usage examples in kata1_test.cpp