Add unit tests for next difficulty calculations

Split GetNextWorkRequired() into two functions to allow the difficulty calculations to
be tested without requiring a full blockchain.
Add unit tests to cover basic difficulty calculation, plus each of the min/max actual
time, and maximum difficulty target conditions.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/pow.h b/src/pow.h
index 3337a30a5e..a5fbba6236 100644
--- a/src/pow.h
+++ b/src/pow.h
@@ -14,6 +14,7 @@ class uint256;
 class arith_uint256;
 
 unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock);
+unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime);
 
 /** Check whether a block hash satisfies the proof-of-work requirement specified by nBits */
 bool CheckProofOfWork(uint256 hash, unsigned int nBits);