Resolving actions for eosio.null

[o-alexandrov]

Closes #814
Here is an example completed transaction after the code changes in this PR.

Change Description

There is a regression since eosjs v16 where this repo used to hardcode the eosio.null abi, instead of attempting to fetch it.
The bug is described here: #814

Or to rephrase the issue description above, the problem is:

• the fetch abi request fails when sent to the net: mainnet or testnet
• current version of eosjs is 22, whereas in eosjs 16, there was a hardcoded abi in the source code:
  • https://github.com/EOSIO/eosjs/blob/legacy/src/index.js#L79
  • with the value here https://github.com/EOSIO/eosjs/blob/legacy/src/schema/eosio.null.abi.json

API Changes

• API Changes

The cachedAbi is initialized with a hardcoded abi for eosio.null.
So developers could make the transactions unique, by adding either an action or a context_free_action, example below:

context_free_actions: [
  {
    account: `eosio.null`,
    name: `nonce`,
    authorization: [],
    data: { value: `test data` },
  },
],

[o-alexandrov]

@bradlhart
Could you please let me know what is missing here or how could I assist so we merge it?

[o-alexandrov]

@bradlhart could you please update here?

• or maybe, do you see readonly transactions as an alternative to nonce?