Avoid generating genesis state in blockchain test runner

[s1na]

blockchain tests don't need to generate the gensis state as they come with their own pre world state. Avoiding this extra generation resulted in the duration of npm run testBlockchain going from 17m down to 2m on my local machine 😁

This is done via a trick: runBlockchain generates the genesis state when current state root doesn't match with the genesis state's root. So I manually manipulate vm._common.genesis().stateRoot to avoid generating the state.

I checked the source code, and this shouldn't have a side-effect (common.genesis().stateRoot doesn't seem to be used elsewhere). But still this is a trick and ideally runBlockchain would accept an option to disable generating genesis state (which would be a breaking change because it changes the parameter ordering, so I didn't go for it).

[holgerd77]

Ups. 😀 What a great improvement! Phew.

Can you rebase, the branch is outdated?

[coveralls]

Coverage remained the same at 94.992% when pulling 5be8a1d on test/bc-genesis-state into c3311b6 on master.

[s1na]

Updated :)

[holgerd77]

Looks good.