Bits in hex for rpc block methods

[braydonf]

Follow-up of #919

[tynes]

There is prior art for using hex32 to convert the bits Number to a hex string.

bcoin/lib/node/rpc.js

Line 1480 in d334051

bits: hex32(attempt.bits),

In the test, 207fffff is used. This matches the value used to create the genesis block in regtest here:

bcoin/scripts/gen.js

Line 82 in d334051

bits: 545259519,

(545259519).toString(16)
'207fffff'

My only concern is that it couples the test to not mining any blocks beforehand, since the hex string is hardcoded in. Not the largest problem because other tests do the same thing, but I think it would be more ideal to not couple tests to specific blockheights unless they are specifically testing the blockheight.

Looks good to me.

ACK d334051

[braydonf]

As these tests become more numerous, I think we'll need to breakout the tests into a few groups based on their expected environments, for example: 1) Basic chain 2) Chain with reorganization. For other cases, it'll probably be necessary to start to use a mocked chain.

[braydonf]

The value here matches the bitcoind return value for bits, as from blockToJSON defined in src/rpc/blockchain.cpp:

result.pushKV("bits", strprintf("%08x", block.nBits));

[braydonf]

For background, bitcoind has had bits expressed in hex since the field was added in bitcoin/bitcoin#885 after the method was added in bitcoin/bitcoin#727.