Increase test coverage for chain

[pinheadmz]

• Replace TODO with actual test for sigops limits
• fix CSV test (see chain-test: cover CSV by time bcoin-org/bcoin#613)
• test checkpoints (see Fix and enable checkpoints for mainnet (WIP) #597)
• improve checkpoints test with airdrop test and coin supply audit

[coveralls]

Pull Request Test Coverage Report for Build 1259118998

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 17 unchanged lines in 8 files lost coverage.
• Overall coverage increased (+0.2%) to 62.054%

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Files with Coverage Reduction	New Missed Lines	%
lib/node/fullnode.js	1	69.83%
lib/node/http.js	1	55.01%
lib/node/rpc.js	1	30.03%
lib/primitives/tx.js	2	69.05%
lib/script/script.js	2	63.44%
lib/wallet/nodeclient.js	2	67.57%
lib/wallet/walletdb.js	2	79.02%
lib/mempool/mempool.js	6	62.82%

Totals
Change from base Build 1230772309:	0.2%
Covered Lines:	21074
Relevant Lines:	31726

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💛 - Coveralls

[pinheadmz]

Added test for checkpoints. What we do is generate a chain with a variety of transactions (auctions, name claims, undependable outputs, etc) then add each block into a fresh chain object. The second time we do this, the fresh chain has a checkpoint just below the tip. Before rebasing on master branch which includes the checkpoints fix (#597) the test fails with this output:

  1) Checkpoints
       Sync with checkpoints
         should sync chain:

      Error: Sync failure at height 204 (register reserved): Database inconsistency.

      throw new Error(
            ^

      at Context.<anonymous> (/Users/matthewzipkin/Desktop/work/hsd/test/chain-checkpoints-test.js:246:17)

Note that the failure is labeled! During the initial chain-generation process, we also build an array of strings that label every single block! If sync fails, the label for the failed block is looked up and printed in the error message ;-)

[nodech]

I noticed CSV tests are duplicated in test/node-test.js as well, I think all related tests for nSequence and nLocktime could be moved out from both node-test and chain-test.js into chain-cltv-csv-test.js or chain-locktime-test.js (even chain-sequence-locktime-test.js?)

[nodech]

• Sigop comments
• More CSV test refactor

Other than these two, everything LGTM !
Great tests !!! 👏

[pinheadmz]

@nodech I cleaned up the nits you found and refactored the tests so all RPC tests are in the node-rpc-test file, leaving node-test empty and deleted it!

I also moved the CSV tests to a new file... for the old file the tests that check chain height and wallet balance. Well, you know those broke and you can probably guess how I fixed them 😬