Merge #11121: TestNode tidyups

7148b74dc [tests] Functional tests must explicitly set num_nodes (John Newbery)
5448a1471 [tests] don't override __init__() in individual tests (John Newbery)
6cf094a02 [tests] Avoid passing around member variables in test_framework (John Newbery)
36b626867 [tests] TestNode: separate add_node from start_node (John Newbery)
be2a2ab6a [tests] fix - use rpc_timeout as rpc timeout (John Newbery)

Pull request description:

  Some additional tidyups after the introduction of TestNode:

  - commit 1 makes TestNode use the correct rpc timeout. This should have been included in #11077
  - commit 2 separates `add_node()` from `start_node()` as originally discussed here: https://github.com/bitcoin/bitcoin/pull/10556#discussion_r121161453 with @kallewoof . The test writer no longer needs to assign to `self.nodes` when starting/stopping nodes.
  - commit 3 adds a `set_test_params()` method, so individual tests don't need to override `__init__()` and call `super().__init__()`

Tree-SHA512: 0adb030623b96675b5c29e2890ce99ccd837ed05f721d0c91b35378c5ac01b6658174aac12f1f77402e1d38b61f39b3c43b4df85c96952565dde1cda05b0db84

test/functional/wallet-dump.py

@@ -56,10 +56,7 @@ def read_dump(file_name, addrs, hd_master_addr_old):
 
 
 class WalletDumpTest(BitcoinTestFramework):
-
-    def __init__(self):
-        super().__init__()
-        self.setup_clean_chain = False
+    def set_test_params(self):
         self.num_nodes = 1
         self.extra_args = [["-keypool=90"]]
 
@@ -68,7 +65,8 @@ class WalletDumpTest(BitcoinTestFramework):
         # longer than the default 30 seconds due to an expensive
         # CWallet::TopUpKeyPool call, and the encryptwallet RPC made later in
         # the test often takes even longer.
-        self.nodes = self.start_nodes(self.num_nodes, self.options.tmpdir, self.extra_args, timewait=60)
+        self.add_nodes(self.num_nodes, self.extra_args, timewait=60)
+        self.start_nodes()
 
     def run_test (self):
         tmpdir = self.options.tmpdir
@@ -95,7 +93,7 @@ class WalletDumpTest(BitcoinTestFramework):
 
         #encrypt wallet, restart, unlock and dump
         self.nodes[0].node_encrypt_wallet('test')
-        self.nodes[0] = self.start_node(0, self.options.tmpdir, self.extra_args[0])
+        self.start_node(0)
         self.nodes[0].walletpassphrase('test', 10)
         # Should be a no-op:
         self.nodes[0].keypoolrefill()