The mock server stops taking the test host down with it - #146
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A run on #145 died with "Server error: OnClientDisconnected is not bound!" and "Test host process crashed". The chain, in order: Server's constructor called start(), so the socket accepted connections before the caller had bound a single handler. CreateMockRippled.Start() binds after constructing, OnClientDisconnected last of the four, leaving a window where the server was live and had no subscribers. MockClient.messageCallback is a socket callback, so it runs on a thread-pool thread. When the socket faults it enters its own catch, and that catch calls ClientDisconnect - which threw when nothing was subscribed. An exception raised inside a catch block on a pool thread has nowhere left to go, so the runtime ends the process. That last part is what makes this worth more than a rerun. An aborted run does not report the tests it never reached: CI shows one failed job where in truth an unknown number of tests did not execute. The failure hides its own size, and the only thing that saved it from being silent is the non-zero exit code. Three changes, each closing one link: Events no longer throw when unsubscribed - all four now use ?.Invoke. For an event, having no subscriber is a legitimate state, not a server fault, and these fire from threads where a throw is not a failed assertion. Handlers are bound before the socket accepts. The constructor no longer listens; StartListening() is explicit, and CreateMockRippled calls it inside the same lock that guards Stop(), so nothing slips between publishing the server and it beginning to accept. This closes the window rather than merely surviving it: a request arriving before OnMessageReceived was bound used to go unanswered, which a test sees as a timeout rather than as a race. _clients is guarded. It was mutated from accept and disconnect callbacks - both pool threads - and read from the test thread with no synchronisation. An add during an enumeration throws InvalidOperationException on a thread with no catch above it: the same fatal shape by a different route. Four tests pin the invariants. Restoring the throw in ClientDisconnect fails two of them. Six consecutive local runs of the unit suite are clean, though that is weak evidence about a rare race - the argument is the mechanism, not the sample. No CHANGES.md entry: this is test infrastructure with no consumer-visible effect, the same call made for the test-only #139.
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📝 WalkthroughWalkthroughThe mock Rippled server now synchronizes client access, supports explicit listener startup, handles missing event subscribers, and coordinates startup with shutdown. New tests cover concurrency and lifecycle behavior. ChangesMock server hardening
Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: ⚪ Minimal · up to The PR addresses the mock-server startup and concurrency failures; the remaining concern is limited to strengthening a test assertion that explicitly verifies socket binding. No actionable merge-blocking risk remains after normal review and checks. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✨ Finishing Touches📝 Generate docstrings
🧪 Generate unit tests (beta)
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In `@Tests/Xrpl.Tests/Client/TestUMockRippledServer.cs`:
- Around line 127-135: Update the test around StartListening to assert
server.GetSocket().IsBound is false before calling StartListening and true
afterward, while retaining the existing socket non-null assertion and
connected-client checks.
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Tests/Xrpl.Tests/Client/TestUMockRippledServer.csTests/Xrpl.Tests/CreateMockRippled.csTests/Xrpl.Tests/MockRippled/Server.cs
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Review catch. Asserting GetSocket() is non-null passes whether or not StartListening() does anything, which makes it no test of the split it was written to pin. IsBound is the actual invariant: false after construction, true after listening.
Review findings. TestUTheClientListToleratesConcurrentUse pinned nothing. It churned ClientDisconnect(null) against readers, but the list then stays empty, and List<T>.Remove of an absent element returns without touching the version counter an enumerator checks - so no mutation ever raced an enumeration. The test passed with _clientsLock removed outright; verified by replacing it with a fresh object per access, which disables mutual exclusion entirely. It now drives real clients over loopback sockets: two threads add and remove while two more walk the list end to end. Same mutation now fails it, which is the whole point of writing it down. TrackClient() is extracted from the accept callback so the add side is reachable without a socket handshake. It is the same code, under the same lock. The handshake read in connectionCallback is now bounded at five seconds. BeginAccept can complete synchronously when a connection is already pending, in which case that blocking read runs on the thread that called StartListening - which holds _serverLock - so a client that connects and then says nothing would hold up Stop() indefinitely. Narrow, but this change exists to remove a hang. And TestUStoppingAServerThatNeverListenedIsQuiet said "and stopping twice is too" while stopping once. It stops twice now.
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The flake that aborted a run on #145:
The chain
Server's constructor calledstart(), so the socket accepted connections before the caller had bound a single handler.CreateMockRippled.Start()binds afterwards,OnClientDisconnectedlast of four — a window where the server is live with no subscribers.MockClient.messageCallbackis a socket callback, so it runs on a thread-pool thread. When the socket faults it enters its owncatch, and that catch callsClientDisconnect, which threw when nothing was subscribed.My first reading was that teardown unsubscribed the handler. It does not —
Server.Stop()never touches the events. The null window is at startup, not shutdown.Why this is worth more than a rerun
An aborted run does not report the tests it never reached. CI showed one failed job where in truth an unknown number of tests did not execute — the
Xrpl.X402.Testsproject was reported as failing and has nothing to do with any of this; it was simply in the same process.A failure that hides its own size is worse than a loud one, and the only thing keeping this from being silent is the non-zero exit code.
Three changes, one per link
Events no longer throw when unsubscribed. All four move to
?.Invoke. For an event, no subscriber is a legitimate state rather than a server fault — and these fire from threads where a throw is not a failed assertion but a dead process.Handlers are bound before the socket accepts. The constructor no longer listens;
StartListening()is explicit, called inside the same lock that guardsStop()so nothing slips between publishing the server and it beginning to accept. This closes the window rather than surviving it: a request arriving beforeOnMessageReceivedwas bound used to go unanswered, which a test sees as a timeout, not a race._clientsis guarded. It was added to from the accept callback, removed from on disconnect — both pool threads — and read from the test thread, unsynchronised. An add during an enumeration throwsInvalidOperationExceptionon a thread with no catch above it: the same fatal shape by a different route. Subscribers are invoked outside the lock, so no handler ever runs while it is held.Evidence
throwinClientDisconnectThe six clean runs are deliberately listed last, because they are the weakest evidence here: the original flake was rare, and six passes say little about a race. The argument is the mechanism — the throw is gone from the path, the window that made handlers null is closed, and the unguarded list is guarded.
No changelog entry
Test infrastructure with no consumer-visible effect. Same call as the test-only #139, which has no
CHANGES.mdentry either.Summary by CodeRabbit
Bug Fixes
Tests