Use COINBASE_MATURITY constant in functional tests.

test/functional/rpc_dumptxoutset.py

@@ -4,6 +4,8 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test the generation of UTXO snapshots using `dumptxoutset`.
 """
+
+from test_framework.blocktools import COINBASE_MATURITY
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_raises_rpc_error
 
@@ -21,7 +23,7 @@ class DumptxoutsetTest(BitcoinTestFramework):
         node = self.nodes[0]
         mocktime = node.getblockheader(node.getblockhash(0))['time'] + 1
         node.setmocktime(mocktime)
-        node.generate(100)
+        node.generate(COINBASE_MATURITY)
 
         FILENAME = 'txoutset.dat'
         out = node.dumptxoutset(FILENAME)