test: added coverage to estimatefee

Added a assert for an rpc error when we try to estimate fee for the max
conf_target

Author: kevkevinpal

test/functional/rpc_estimatefee.py

@@ -36,6 +36,9 @@ def run_test(self):
         assert_raises_rpc_error(-1, "estimatesmartfee", self.nodes[0].estimatesmartfee, 1, 'ECONOMICAL', 1)
         assert_raises_rpc_error(-1, "estimaterawfee", self.nodes[0].estimaterawfee, 1, 1, 1)
 
+        # max value of 1008 per src/policy/fees.h
+        assert_raises_rpc_error(-8, "Invalid conf_target, must be between 1 and 1008", self.nodes[0].estimaterawfee, 1009)
+
         # valid calls
         self.nodes[0].estimatesmartfee(1)
         # self.nodes[0].estimatesmartfee(1, None)