Add test for empty chain and reorg consistency for gettxoutsetinfo.

Author: gmaxwell

test/functional/blockchain.py

@@ -32,7 +32,7 @@ class BlockchainTest(BitcoinTestFramework):
     def __init__(self):
         super().__init__()
         self.setup_clean_chain = False
-        self.num_nodes = 2
+        self.num_nodes = 1
 
     def run_test(self):
         self._test_gettxoutsetinfo()
@@ -50,9 +50,33 @@ def _test_gettxoutsetinfo(self):
         assert_equal(res['height'], 200)
         assert_equal(res['txouts'], 200)
         assert_equal(res['bytes_serialized'], 13924),
+        assert_equal(res['bestblock'], node.getblockhash(200))
         assert_equal(len(res['bestblock']), 64)
         assert_equal(len(res['hash_serialized']), 64)
 
+        self.log.info("Test that gettxoutsetinfo() works for blockchain with just the genesis block")
+        b1hash = node.getblockhash(1)
+        node.invalidateblock(b1hash)
+
+        res2 = node.gettxoutsetinfo()
+        assert_equal(res2['transactions'], 0)
+        assert_equal(res2['total_amount'], Decimal('0'))
+        assert_equal(res2['height'], 0)
+        assert_equal(res2['txouts'], 0)
+        assert_equal(res2['bestblock'], node.getblockhash(0))
+        assert_equal(len(res2['hash_serialized']), 64)
+
+        self.log.info("Test that gettxoutsetinfo() returns the same result after invalidate/reconsider block")
+        node.reconsiderblock(b1hash)
+
+        res3 = node.gettxoutsetinfo()
+        assert_equal(res['total_amount'], res3['total_amount'])
+        assert_equal(res['transactions'], res3['transactions'])
+        assert_equal(res['height'], res3['height'])
+        assert_equal(res['txouts'], res3['txouts'])
+        assert_equal(res['bestblock'], res3['bestblock'])
+        assert_equal(res['hash_serialized'], res3['hash_serialized'])
+
     def _test_getblockheader(self):
         node = self.nodes[0]