Enforce hex prefixing for address strings

[cgewecke]

Part of #172 Breaking API Changes

The proposal to make hex param checking more strict in #172 comes out of review discussions in #170. There @holger suggested:

Then we should at least pass input params to a dedicated check method and throw if no hex-prefix provided, and always return prefixed hex strings.

PR adds logic to enforce hex-prefixing for all address string inputs. Affected methods are:

• isValidAddress
• isZeroAddress
• toChecksumAddress
• isValidChecksumAddress (via isValidAddress)

isPrecompile is excluded because it's targeted for removal in #242.

[github-actions]

Coverage increased (+0.01%) to 99.656% when pulling 5670bdd on enforce-hex-value-format into 3bbc948 on master.

[lgtm-com]

This pull request introduces 1 alert when merging 5670bdd into 3bbc948 - view on LGTM.com

new alerts:

• 1 for Unused variable, import, function or class

[cgewecke]

Using isHexString instead of isHexPrefixed here because the latter throws its own error if given a non-string input.

[holgerd77]

@cgewecke Great, thanks for picking this up! 😄 Did I mention that you should really question what's written up in the API Change Table and give this also your own thoughts respectively reflect if you see these as useful/adequate API changes.

I've written this up quite some time ago and there actually was not yet much discussion around this yet, so I would encourage all others to give this some thought as well.

[holgerd77]

This looks all good, will merge here as well.

[holgerd77]

Nice. 👍