Switch testing framework from MAIN to new UNITTEST network

UNITTEST inherites from MAIN but allows synamically changing its parameters using the ModifiableParams() interface

src/test/base58_tests.cpp

@@ -175,7 +175,7 @@ BOOST_AUTO_TEST_CASE(base58_keys_valid_parse)
             BOOST_CHECK_MESSAGE(!secret.IsValid(), "IsValid pubkey as privkey:" + strTest);
         }
     }
-    SelectParams(CBaseChainParams::MAIN);
+    SelectParams(CBaseChainParams::UNITTEST);
 }
 
 // Goal: check that generated keys match test vectors
@@ -243,7 +243,7 @@ BOOST_AUTO_TEST_CASE(base58_keys_valid_gen)
     CTxDestination nodest = CNoDestination();
     BOOST_CHECK(!dummyAddr.Set(nodest));
 
-    SelectParams(CBaseChainParams::MAIN);
+    SelectParams(CBaseChainParams::UNITTEST);
 }
 
 // Goal: check that base58 parsing code is robust against a variety of corrupted data

src/test/miner_tests.cpp

@@ -253,6 +253,7 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
 
     chainActive.Tip()->nHeight--;
     SetMockTime(0);
+    mempool.clear();
 
     BOOST_FOREACH(CTransaction *tx, txFirst)
         delete tx;

src/test/test_bitcoin.cpp

@@ -31,7 +31,7 @@ struct TestingSetup {
 
     TestingSetup() {
         fPrintToDebugLog = false; // don't want to write to debug.log file
-        SelectParams(CBaseChainParams::MAIN);
+        SelectParams(CBaseChainParams::UNITTEST);
         noui_connect();
 #ifdef ENABLE_WALLET
         bitdb.MakeMock();