Multiplayer, Network, and Online Service Testing
What this domain tests
Multiplayer and online testing covers the behaviour of a game when the network is imperfect, when services fail, and when many players act at once. The exam targets latency, packet loss, matchmaking, session state, server authority and load testing.
Core rules
- Network conditions to test: latency, jitter, packet loss, bandwidth limits, NAT type and relay versus direct connections.
- Know the topology: peer-to-peer, listen server, dedicated server, or relay. Each fails differently, and host migration only applies to some.
- Test negative paths: server unavailable, login timeout, duplicate login, matchmaking timeout, party member drops, reconnection after suspend.
- Server authority matters: a client that can set its own health, currency or position is an exploit.
- Soak and load tests: long sessions for memory leaks, many concurrent bots for matchmaking and backend limits, and recovery after a service restart.
- Use network simulation tools and packet captures so a report shows conditions, not guesses.
Worked example
In four-player co-op, the host quits during a boss fight. The design says the session should migrate to another player within 10 seconds and preserve boss health. Observed: the session ends and all clients return to the main menu. Reasoning: reproduce with a controlled disconnect rather than closing the application, capture logs from all four clients, and check whether the boss state was server-authoritative. If state lived only on the host, migration cannot preserve it, so the defect is a design-level issue to raise with the engineering lead, not just a client bug. The report includes the network topology and timestamps from each client.
Traps
Testing only on a LAN. Simulating latency but not packet loss or jitter. Treating 'no crash' as a pass. No soak test before launch. Not testing duplicate logins or server restarts. Ignoring clock skew and time zones in events and leaderboards. Forgetting cross-play and cross-save combinations.