[tests] Update start/stop node functions to be private module functions

This commit marks the start/stop functions in util.py as private module
functions. A future PR will remove these entirely and move the
functionality directly into the BitcoinTestFramework class, but setting them as
private in this PR will prevent anyone from accidentally calling them
before that future PR is merged.

test/functional/test_framework/test_framework.py

@@ -31,10 +31,10 @@ from .util import (
     p2p_port,
     rpc_url,
     set_node_times,
-    start_node,
-    start_nodes,
-    stop_node,
-    stop_nodes,
+    _start_node,
+    _start_nodes,
+    _stop_node,
+    _stop_nodes,
     sync_blocks,
     sync_mempools,
     wait_for_bitcoind_start,
@@ -91,7 +91,7 @@ class BitcoinTestFramework(object):
         extra_args = None
         if hasattr(self, "extra_args"):
             extra_args = self.extra_args
-        self.nodes = start_nodes(self.num_nodes, self.options.tmpdir, extra_args)
+        self.nodes = _start_nodes(self.num_nodes, self.options.tmpdir, extra_args)
 
     def run_test(self):
         raise NotImplementedError
@@ -194,16 +194,16 @@ class BitcoinTestFramework(object):
     # Public helper methods. These can be accessed by the subclass test scripts.
 
     def start_node(self, i, dirname, extra_args=None, rpchost=None, timewait=None, binary=None, stderr=None):
-        return start_node(i, dirname, extra_args, rpchost, timewait, binary, stderr)
+        return _start_node(i, dirname, extra_args, rpchost, timewait, binary, stderr)
 
     def start_nodes(self, num_nodes, dirname, extra_args=None, rpchost=None, timewait=None, binary=None):
-        return start_nodes(num_nodes, dirname, extra_args, rpchost, timewait, binary)
+        return _start_nodes(num_nodes, dirname, extra_args, rpchost, timewait, binary)
 
     def stop_node(self, num_node):
-        stop_node(self.nodes[num_node], num_node)
+        _stop_node(self.nodes[num_node], num_node)
 
     def stop_nodes(self):
-        stop_nodes(self.nodes)
+        _stop_nodes(self.nodes)
 
     def split_network(self):
         """

test/functional/test_framework/util.py

@@ -227,10 +227,11 @@ def wait_for_bitcoind_start(process, url, i):
         time.sleep(0.25)
 
 
-def start_node(i, dirname, extra_args=None, rpchost=None, timewait=None, binary=None, stderr=None):
-    """
-    Start a bitcoind and return RPC connection to it
-    """
+def _start_node(i, dirname, extra_args=None, rpchost=None, timewait=None, binary=None, stderr=None):
+    """Start a bitcoind and return RPC connection to it
+
+    This function should only be called from within test_framework, not by individual test scripts."""
+
     datadir = os.path.join(dirname, "node"+str(i))
     if binary is None:
         binary = os.getenv("BITCOIND", "bitcoind")
@@ -251,8 +252,8 @@ def start_node(i, dirname, extra_args=None, rpchost=None, timewait=None, binary=
 def assert_start_raises_init_error(i, dirname, extra_args=None, expected_msg=None):
     with tempfile.SpooledTemporaryFile(max_size=2**16) as log_stderr:
         try:
-            node = start_node(i, dirname, extra_args, stderr=log_stderr)
-            stop_node(node, i)
+            node = _start_node(i, dirname, extra_args, stderr=log_stderr)
+            _stop_node(node, i)
         except Exception as e:
             assert 'bitcoind exited' in str(e) #node must have shutdown
             if expected_msg is not None:
@@ -267,10 +268,11 @@ def assert_start_raises_init_error(i, dirname, extra_args=None, expected_msg=Non
                 assert_msg = "bitcoind should have exited with expected error " + expected_msg
             raise AssertionError(assert_msg)
 
-def start_nodes(num_nodes, dirname, extra_args=None, rpchost=None, timewait=None, binary=None):
-    """
-    Start multiple bitcoinds, return RPC connections to them
-    """
+def _start_nodes(num_nodes, dirname, extra_args=None, rpchost=None, timewait=None, binary=None):
+    """Start multiple bitcoinds, return RPC connections to them
+    
+    This function should only be called from within test_framework, not by individual test scripts."""
+
     if extra_args is None: extra_args = [ None for _ in range(num_nodes) ]
     if binary is None: binary = [ None for _ in range(num_nodes) ]
     assert_equal(len(extra_args), num_nodes)
@@ -278,16 +280,20 @@ def start_nodes(num_nodes, dirname, extra_args=None, rpchost=None, timewait=None
     rpcs = []
     try:
         for i in range(num_nodes):
-            rpcs.append(start_node(i, dirname, extra_args[i], rpchost, timewait=timewait, binary=binary[i]))
+            rpcs.append(_start_node(i, dirname, extra_args[i], rpchost, timewait=timewait, binary=binary[i]))
     except: # If one node failed to start, stop the others
-        stop_nodes(rpcs)
+        _stop_nodes(rpcs)
         raise
     return rpcs
 
 def log_filename(dirname, n_node, logname):
     return os.path.join(dirname, "node"+str(n_node), "regtest", logname)
 
-def stop_node(node, i):
+def _stop_node(node, i):
+    """Stop a bitcoind test node
+
+    This function should only be called from within test_framework, not by individual test scripts."""
+
     logger.debug("Stopping node %d" % i)
     try:
         node.stop()
@@ -297,9 +303,13 @@ def stop_node(node, i):
     assert_equal(return_code, 0)
     del bitcoind_processes[i]
 
-def stop_nodes(nodes):
+def _stop_nodes(nodes):
+    """Stop multiple bitcoind test nodes
+
+    This function should only be called from within test_framework, not by individual test scripts."""
+
     for i, node in enumerate(nodes):
-        stop_node(node, i)
+        _stop_node(node, i)
     assert not bitcoind_processes.values() # All connections must be gone now
 
 def set_node_times(nodes, t):