Merge bitcoin/bitcoin#27453: test: added coverage to rpc_scantxoutset.py

24d55fb test: added coverage to rpc_scantxoutset.py (kevkevin)

Pull request description:

  Included a test that checks if an invalid first argument is entered we receive a rpc error. The rpc should fail if "start", "status" or "abort" is not the first command.

  Relavant: mentioned in bitcoin/bitcoin#27422

ACKs for top commit:
  MarcoFalke:
    lgtm ACK 24d55fb
  theStack:
    ACK 24d55fb

Tree-SHA512: 4b804235d3fa17c7bf492068ab47c1f87cb6cfc1a428c51e273ec059d3c41f581bcc467bb5d6d8bbf2fab14c60cd1c52a30c50009efe1c9b5adee70c88897ad9

test/functional/rpc_scantxoutset.py

@@ -123,6 +123,9 @@ def run_test(self):
         # Check that second arg is needed for start
         assert_raises_rpc_error(-1, "scanobjects argument is required for the start action", self.nodes[0].scantxoutset, "start")
 
+        # Check that invalid command give error
+        assert_raises_rpc_error(-8, "Invalid action 'invalid_command'", self.nodes[0].scantxoutset, "invalid_command")
+
 
 if __name__ == "__main__":
     ScantxoutsetTest().main()