run tests outside of nim compilation (#463)

else we need memory for both compiler and test

chronos.nimble

@@ -13,6 +13,8 @@ requires "nim >= 1.6.0",
          "httputils",
          "unittest2"
 
+import os
+
 let nimc = getEnv("NIMC", "nim") # Which nim compiler to use
 let lang = getEnv("NIMLANG", "c") # Which backend (c/cpp/js)
 let flags = getEnv("NIMFLAGS", "") # Extra flags for the compiler
@@ -44,7 +46,8 @@ proc build(args, path: string) =
   exec nimc & " " & lang & " " & cfg & " " & flags & " " & args & " " & path
 
 proc run(args, path: string) =
-  build args & " -r", path
+  build args, path
+  exec "build/" & path.splitPath[1]
 
 task test, "Run all tests":
   for args in testArguments: