use abstract sax class in parser tests

test/src/unit-class_parser.cpp

@@ -129,68 +129,68 @@ class SaxEventLogger
     bool errored = false;
 };
 
-class SaxCountdown
+class SaxCountdown : public nlohmann::json::json_sax_t
 {
   public:
     explicit SaxCountdown(const int count) : events_left(count)
     {}
 
-    bool null()
+    bool null() override
     {
         return events_left-- > 0;
     }
 
-    bool boolean(bool)
+    bool boolean(bool) override
     {
         return events_left-- > 0;
     }
 
-    bool number_integer(json::number_integer_t)
+    bool number_integer(json::number_integer_t) override
     {
         return events_left-- > 0;
     }
 
-    bool number_unsigned(json::number_unsigned_t)
+    bool number_unsigned(json::number_unsigned_t) override
     {
         return events_left-- > 0;
     }
 
-    bool number_float(json::number_float_t, const std::string&)
+    bool number_float(json::number_float_t, const std::string&) override
     {
         return events_left-- > 0;
     }
 
-    bool string(std::string&)
+    bool string(std::string&) override
     {
         return events_left-- > 0;
     }
 
-    bool start_object(std::size_t)
+    bool start_object(std::size_t) override
     {
         return events_left-- > 0;
     }
 
-    bool key(std::string&)
+    bool key(std::string&) override
     {
         return events_left-- > 0;
     }
 
-    bool end_object()
+    bool end_object() override
     {
         return events_left-- > 0;
     }
 
-    bool start_array(std::size_t)
+    bool start_array(std::size_t) override
     {
         return events_left-- > 0;
     }
 
-    bool end_array()
+    bool end_array() override
     {
         return events_left-- > 0;
     }
 
-    bool parse_error(std::size_t, const std::string&, const json::exception&)
+    bool parse_error(std::size_t, const std::string&, const json::exception&) override
     {
         return false;
     }