esphome/tests/components/json/common.yaml

json:

interval:
  - interval: 60s
    then:
      - lambda: |-
          // Test build_json - returns SerializationBuffer, use auto to avoid heap allocation
          auto json_buf = esphome::json::build_json([](JsonObject root) {
            root["sensor"] = "temperature";
            root["value"] = 23.5;
            root["unit"] = "°C";
          });
          ESP_LOGD("test", "Built JSON: %s", json_buf.c_str());

          // Test parse_json - implicit conversion to std::string for backward compatibility
          std::string json_str = json_buf;
          bool parse_ok = esphome::json::parse_json(json_str, [](JsonObject root) {
            if (root["sensor"].is<const char*>() && root["value"].is<float>()) {
              const char* sensor = root["sensor"];
              float value = root["value"];
              ESP_LOGD("test", "Parsed: sensor=%s, value=%.1f", sensor, value);
              return true;
            } else {
              ESP_LOGD("test", "Parsed JSON missing required keys");
              return false;
            }
          });
          ESP_LOGD("test", "Parse result (JSON syntax only): %s", parse_ok ? "success" : "failed");

          // Test JsonBuilder class - returns SerializationBuffer
          esphome::json::JsonBuilder builder;
          JsonObject obj = builder.root();
          obj["test"] = "direct_builder";
          obj["count"] = 42;
          auto result = builder.serialize();
          ESP_LOGD("test", "JsonBuilder result: %s", result.c_str());