net: Use mockable time for ping/pong, add tests

test/functional/feature_maxuploadtarget.py

@@ -35,7 +35,11 @@ class MaxUploadTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 1
-        self.extra_args = [["-maxuploadtarget=800", "-acceptnonstdtxn=1"]]
+        self.extra_args = [[
+            "-maxuploadtarget=800",
+            "-acceptnonstdtxn=1",
+            "-peertimeout=9999",  # bump because mocktime might cause a disconnect otherwise
+        ]]
         self.supports_cli = False
 
         # Cache for utxos, as the listunspent may take a long time later in the test