Error message for mnemonics (mnemonic_sentence and mnemonic_second_factor)

[piotr-iohk]

Release	Operating System	Cause
next	Linux	Code

Context

Error message for mnemonic_sentence and mnemonic_second_factor need to be improved:

E.g. when doing POST v2\wallets and providing invalid mnemonic sentence or valid mnemonic sentence but with invalid length to one of the parameters the following error is returned:

Error in $['mnemonic_sentence']: ErrMnemonicWords (ErrWrongNumberOfWords 12 24)

• the error is not really human friendly and can be misleading
• it is faultly thrown for the case when the number of words is valid but mnemonics are invalid
• it is faulty thrown for the non-english mnemonics (ErrMnemonicWords (ErrWrongNumberOfWords instead of ErrDictionary (ErrInvalidDictionaryWord)

Steps to Reproduce

Please note that examples are for mnemonic_sentence but the same situation adheres to mnemonic_second_factor.

0. start cardano wallet launcher:

export NETWORK=testnet
stack exec -- cardano-wallet-launcher

Case 1 - invalid mnemonics, valid length

1. Run post wallet with invalid mnemonics list, yet make sure list has valid length (e.g. 15)

curl  -vX POST http://localhost:8090/v2/wallets \
  -H "Accept: application/json; charset=utf-8" \
  -H "Content-Type: application/json; charset=utf-8" \
  -d '{
"name": "Piotr Wallet",
"mnemonic_sentence": ["word","word","word","word","word","word","word","word","word","word","word","word","word","word","word"],
"passphrase": "Secure Passphrase",
"address_pool_gap": 20
}' --http1.1

Case 2 - valid mnemonics, invalid length

1. Run post wallet with valid mnemonics list, yet make sure list has invalid length (e.g. 9)

curl  -vX POST http://localhost:8090/v2/wallets \
  -H "Accept: application/json; charset=utf-8" \
  -H "Content-Type: application/json; charset=utf-8" \
  -d '{
"name": "Piotr Wallet",
"mnemonic_sentence": ["subway", "tourist", "abstract", "roast", "border", "curious",
        "exercise", "work", "narrow"],
"passphrase": "Secure Passphrase",
"address_pool_gap": 20
}' --http1.1

Case 3 - valid, yet non-english mnemonics

curl  -vX POST http://localhost:8090/v2/wallets \
  -H "Accept: application/json; charset=utf-8" \
  -H "Content-Type: application/json; charset=utf-8" \
  -d '{
"name": "Piotr Wallet",
"mnemonic_sentence": ["盗", "精", "序", "郎", "赋", "姿", "委", "善", "酵",
        "祥", "赛", "矩", "蜡", "注", "韦", "效", "义", "冻"],
"passphrase": "Secure Passphrase",
"address_pool_gap": 20
}' --http1.1

Expected behavior

Case 1 - invalid mnemonics, valid length
The error should be rather something like:
Error in $['mnemonic_sentence']: The list of provided mnemonic words is invalid.

Case 2 - valid mnemonics, invalid length
The error should be rather something like:
Error in $['mnemonic_sentence']: The list of provided mnemonic is too short (9). Supported lengths are 15,18,21,24.

Case 3 - valid, yet non-english mnemonics
Error in $['mnemonic_sentence']: Non-english mnemonic words are not supported

Actual behavior

Case 1 - invalid mnemonics, valid length

The error message returned for the case is:
Error in $['mnemonic_sentence']: ErrMnemonicWords (ErrWrongNumberOfWords 15 24)

Case 2 - valid mnemonics, invalid length
The error message returned for the case is:
Error in $['mnemonic_sentence']: ErrMnemonicWords (ErrWrongNumberOfWords 9 24)

Case 3 - valid, yet non-english mnemonics
Actually the same error is returned -> Error in $['mnemonic_sentence']: ErrMnemonicWords (ErrWrongNumberOfWords 9 24) instead of expected ErrDictionary (ErrInvalidDictionaryWord .... However even the ErrDictionary (ErrInvalidDictionaryWord ... should be polished to be informative and user-friendly as indicated in Expected behavior.

---

Resolution Plan

• The FromMnemonic class used to parse a list of mnemonic words of variable length seems to only report the last error encountered in the list.
• Introducing some failing test case to illustrate this hypothesis and then, if confirmed, fixing it it the way to go.

PR

Number	Base
#197	master

QA

[piotr-iohk]

lgtm 👍
tested on #194