更新：添加doString方法及对应的单元测试

lib/lua_runner.cpp

@@ -209,6 +209,37 @@ int Lua_runner::run(const char *path,const char *arg)
         return -1;
     }
 }
+
+int Lua_runner::dostring(const char *target)
+{
+    if(target == NULL)
+    {
+        errno = NAPI_ERROR_FUNCS;
+        return -1;
+    }
+    if(luaL_dostring(this->L,target) != LUA_OK)
+    {
+        errno = NAPI_ERROR_FUNCS;
+        this->reslt = lua_tostring(this->L,-1);
+        lua_pop(L,1);//错误出栈
+        return -1;
+    }
+    if(lua_gettop(this->L) == 0) {
+        errno = NAPI_SCRIPT_BAD_RET;
+        this->reslt = "";
+        return -1;
+    }
+    if(lua_isstring(this->L,-1)){
+        this->reslt = lua_tostring(this->L,-1);
+        lua_pop(L,1);
+        return 0;
+    }
+    else{
+        errno = NAPI_SCRIPT_BAD_RET;
+        lua_pop(L,1);
+        return -1;
+    }
+}
 //TODO 实现函数调用 achieve func call via file
 /*
 int Lua_runner::callfunction()