Add tests for JSON RPC hex strings

tests/rpcclient/test_hexstrings.nim

@@ -0,0 +1,67 @@
+# Separated from main tests for brevity
+
+import unittest, ../../nimbus/rpc/hexstrings, json
+
+proc doHexStrTests* =
+  suite "Hex quantity":
+    test "Empty string":
+      expect ValueError:
+        let
+          source = ""
+          x = hexQuantityStr source
+        check %x == %source
+    test "Even length":
+      let
+        source = "0x123"
+        x = hexQuantityStr source
+      check %x == %source
+    test "Odd length":
+      let
+        source = "0x123"
+        x = hexQuantityStr"0x123"
+      check %x == %source
+    test "Missing header":
+      expect ValueError:
+        let
+          source = "1234"
+          x = hexQuantityStr source
+        check %x != %source
+      expect ValueError:
+        let
+          source = "01234"
+          x = hexQuantityStr source
+        check %x != %source
+      expect ValueError:
+        let
+          source = "x1234"
+          x = hexQuantityStr source
+        check %x != %source
+      
+  suite "Hex data":
+    test "Even length":
+      let
+        source = "0x1234"
+        x = hexDataStr source
+      check %x == %source
+    test "Odd length":
+      expect ValueError:
+        let
+          source = "0x123"
+          x = hexDataStr source
+        check %x != %source
+    test "Missing header":
+      expect ValueError:
+        let
+          source = "1234"
+          x = hexDataStr source
+        check %x != %source
+      expect ValueError:
+        let
+          source = "01234"
+          x = hexDataStr source
+        check %x != %source
+      expect ValueError:
+        let
+          source = "x1234"
+          x = hexDataStr source
+        check %x != %source

tests/test_rpc.nim

@@ -3,6 +3,9 @@ import
   json_rpc/[rpcserver, rpcclient],
   ../nimbus/rpc/common, ../nimbus/constants, ../nimbus/nimbus/account,
   eth_common
+import rpcclient/test_hexstrings
+
+doHexStrTests()
 
 from os import getCurrentDir, DirSep
 from strutils import rsplit