test: ensure acceptstalefeeestimates is supported only on regtest c…

…hain

test/functional/feature_config_args.py

@@ -371,6 +371,18 @@ def test_ignored_default_conf(self):
             f'is being used instead.') + r"[\s\S]*", env=env, match=ErrorMatch.FULL_REGEX)
         node.args = node_args
 
+    def test_acceptstalefeeestimates_arg_support(self):
+        self.log.info(f"Test -acceptstalefeeestimates option is not supported on non-regtest chains")
+        inc_conf_file_path = os.path.join(self.nodes[0].datadir, 'include.conf')
+        for chain in ["main", "test", "signet"]:
+            with open(inc_conf_file_path, 'w', encoding='utf-8') as conf:
+                conf.write(f'chain={chain}\n')
+                conf.write('acceptstalefeeestimates=1\n')
+            self.nodes[0].assert_start_raises_init_error(extra_args=[f"-conf={inc_conf_file_path}", "-allowignoredconf"], expected_msg=f'Error: acceptstalefeeestimates is not supported on {chain} chain.')
+
+        with open(inc_conf_file_path, 'w', encoding='utf-8') as conf:
+            conf.write('')  # clear
+
     def run_test(self):
         self.test_log_buffer()
         self.test_args_log()
@@ -383,6 +395,7 @@ def run_test(self):
         self.test_invalid_command_line_options()
         self.test_ignored_conf()
         self.test_ignored_default_conf()
+        self.test_acceptstalefeeestimates_arg_support()
 
         # Remove the -datadir argument so it doesn't override the config file
         self.nodes[0].args = [arg for arg in self.nodes[0].args if not arg.startswith("-datadir")]