Add tests for stint return values and parameters

tests/testrpcmacro.nim

@@ -1,4 +1,4 @@
-import unittest, ../ rpcserver, asyncdispatch, json, tables
+import unittest, ../ rpcserver, asyncdispatch, json, tables, stint
 
 type
   # some nested types to check object parsing
@@ -51,6 +51,10 @@ s.on("rpc.seqparam") do(a: string, s: seq[int]):
 s.on("rpc.objparam") do(a: string, obj: MyObject):
   result = %obj
 
+s.on("rpc.uint256param") do(i: UInt256):
+  let r = i + 1.stUint(256)
+  result = %r
+
 s.on("rpc.returntypesimple") do(i: int) -> int:
   result = i
 
@@ -61,6 +65,10 @@ s.on("rpc.returntypecomplex") do(i: int) -> Test2:
 s.on("rpc.testreturns") do() -> int:
   return 1234
 
+s.on("rpc.testreturnuint256") do() -> UInt256:
+  let r: UInt256 = "0x1234567890abcdef".parse(UInt256, 16)
+  return r
+
 # Tests
 suite "Server types":
 
@@ -100,6 +108,10 @@ suite "Server types":
     let r = waitfor rpcObjParam(%[%"abc", testObj])
     check r == testObj
 
+  test "UInt256 param":
+    let r = waitFor rpcUInt256Param(%[%"0x1234567890"])
+    check r == %"0x1234567891"
+
   test "Simple return types":
     let
       inp = %99
@@ -116,6 +128,10 @@ suite "Server types":
     let r = waitFor rpcTestReturns(%[])
     check r == %1234
 
+  test "Return UInt256":
+    let r = waitFor rpcTestReturnUInt256(%[])
+    check r == %"0x1234567890abcdef"
+
   test "Runtime errors":
     expect ValueError:
       # root param not array