Peer-to-peer (P2P) systems have emerged as a fundamental paradigm for decentralized resource sharing, communication, and computation across diverse application domains such as energy trading, distributed storage, social networking, and federated learning. Unlike traditional client–server architectures, P2P networks operate without centralized control, enabling nodes to act as both resource providers and consumers, thereby improving scalability, robustness, and system efficiency . However, the decentralized and dynamic nature of P2P systems introduces significant challenges in ensuring reliability, performance, and security, making testing a critical research area.This paper presents a comprehensive survey of peer-to-peer network testing techniques, integrating insights from existing literature on P2P architectures, simulation frameworks, and application-specific implementations. Early research primarily relied on analytical models and simulations to evaluate P2P systems, as real-world experimentation is often impractical due to large-scale deployment requirements. Simulation-based testing remains a widely adopted approach, though it suffers from limitations such as scalability constraints and lack of reproducibility in complex environments.Modern testing approaches for P2P systems include model-based testing, fault injection, stress testing, fuzzing, differential testing, and concurrency testing. These techniques address key challenges such as validating global system properties, handling peer churn, ensuring consistency, and managing heterogeneous network conditions . Additionally, load testing and performance evaluation methods have evolved to leverage decentralized testing frameworks, eliminating bottlenecks associated with centralized testing systems. Measurement-based techniques and sampling methods are also used to analyze large-scale P2P networks efficiently, though issues such as bias and incomplete data collection persist.The emerging application domains such as P2P energy trading and federated learning introduce new testing requirements, including real-time system validation, privacy preservation, and integration with physical systems. Advanced approaches like hardware-in-the-loop testing and AI-driven evaluation mechanisms are being explored to bridge the gap between simulation and real-world deployment. This survey consolidates key testing methodologies, identifies open challenges, and highlights future research directions in P2P network testing, emphasizing its critical role in enabling reliable, scalable, and intelligent decentralized systems.