What is the name of the type of testing that cannot be done without automated testing?

Performance monitoring and load testing in real operating conditions / production.

Examples may include:

• Performance metrics monitoring: Response time, throughput, resource usage (CPU, RAM) of the server.
• Stability testing under high load: Simulating a large number of concurrent users or requests to identify failure points or performance degradation.
• Scalability testing: Checking system behavior when increasing load or resources.
• A/B testing in production: Comparing two versions of functionality on a subset of real users to assess their impact on key metrics.

These types of testing require continuous data collection, synthetic load generation, or analysis of real user behavior on a large scale, which is practically impossible manually. The results of such testing are often used for decision-making regarding releasing new versions, infrastructure scaling, or code optimization.

An example of a monitoring tool in production:

{
  "service_name": "my-web-service",
  "metrics": {
    "request_duration_ms": {
      "average": 150,
      "p95": 300,
      "max": 1200
    },
    "error_rate_percentage": 0.5,
    "cpu_utilization_percentage": 65
  }
}