rpc, test: Fix error message in getdescriptoractivity

Mark blockhashes and scanobjects arguments as required, so the user receives
a clear help message when either is missing.

Added a new functional test for this use case.

Co-authored-by: stickies-v <[email protected]>

Author: pablomartin4btc

src/rpc/blockchain.cpp

@@ -2193,16 +2193,20 @@ static const auto scan_action_arg_desc = RPCArg{
         "\"status\" for progress report (in %) of the current scan"
 };
 
+static const auto output_descriptor_obj = RPCArg{
+    "", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED, "An object with output descriptor and metadata",
+    {
+        {"desc", RPCArg::Type::STR, RPCArg::Optional::NO, "An output descriptor"},
+        {"range", RPCArg::Type::RANGE, RPCArg::Default{1000}, "The range of HD chain indexes to explore (either end or [begin,end])"},
+    }
+};
+
 static const auto scan_objects_arg_desc = RPCArg{
     "scanobjects", RPCArg::Type::ARR, RPCArg::Optional::OMITTED, "Array of scan objects. Required for \"start\" action\n"
         "Every scan object is either a string descriptor or an object:",
     {
         {"descriptor", RPCArg::Type::STR, RPCArg::Optional::OMITTED, "An output descriptor"},
-        {"", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED, "An object with output descriptor and metadata",
-            {
-                {"desc", RPCArg::Type::STR, RPCArg::Optional::NO, "An output descriptor"},
-                {"range", RPCArg::Type::RANGE, RPCArg::Default{1000}, "The range of HD chain indexes to explore (either end or [begin,end])"},
-            }},
+        output_descriptor_obj,
     },
     RPCArgOptions{.oneline_description="[scanobjects,...]"},
 };
@@ -2632,10 +2636,16 @@ static RPCHelpMan getdescriptoractivity()
         "This command pairs well with the `relevant_blocks` output of `scanblocks()`.\n"
         "This call may take several minutes. If you encounter timeouts, try specifying no RPC timeout (bitcoin-cli -rpcclienttimeout=0)",
         {
-            RPCArg{"blockhashes", RPCArg::Type::ARR, RPCArg::Optional::OMITTED, "The list of blockhashes to examine for activity. Order doesn't matter. Must be along main chain or an error is thrown.\n", {
+            RPCArg{"blockhashes", RPCArg::Type::ARR, RPCArg::Optional::NO, "The list of blockhashes to examine for activity. Order doesn't matter. Must be along main chain or an error is thrown.\n", {
                 {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A valid blockhash"},
             }},
-            scan_objects_arg_desc,
+            RPCArg{"scanobjects", RPCArg::Type::ARR, RPCArg::Optional::NO, "The list of descriptors (scan objects) to examine for activity. Every scan object is either a string descriptor or an object:",
+                {
+                    {"descriptor", RPCArg::Type::STR, RPCArg::Optional::OMITTED, "An output descriptor"},
+                    output_descriptor_obj,
+                },
+                RPCArgOptions{.oneline_description="[scanobjects,...]"},
+            },
             {"include_mempool", RPCArg::Type::BOOL, RPCArg::Default{true}, "Whether to include unconfirmed activity"},
         },
         RPCResult{

test/functional/rpc_getdescriptoractivity.py

@@ -31,6 +31,7 @@ def run_test(self):
         self.test_confirmed_and_unconfirmed(node, wallet)
         self.test_receive_then_spend(node, wallet)
         self.test_no_address(node, wallet)
+        self.test_required_args(node)
 
     def test_no_activity(self, node):
         self.log.info("Test that no activity is found for an unused address")
@@ -231,6 +232,11 @@ def test_no_address(self, node, wallet):
         assert_equal(list(a2['output_spk'].keys()), ['asm', 'desc', 'hex', 'type'])
         assert a2['amount'] == Decimal(no_addr_tx["tx"].vout[0].nValue) / COIN
 
+    def test_required_args(self, node):
+        self.log.info("Test that required arguments must be passed")
+        assert_raises_rpc_error(-1, "getdescriptoractivity", node.getdescriptoractivity)
+        assert_raises_rpc_error(-1, "getdescriptoractivity", node.getdescriptoractivity, [])
+
 
 if __name__ == '__main__':
     GetBlocksActivityTest(__file__).main()