FluxFlow.Components.Expectations 3.0.0

FluxFlow.Components.Expectations

A standalone event-expectation node for FluxFlow.

What it is

EventExpectationNode is a self-contained TPL Dataflow processor built on the FluxFlow.Nodes kit. You give it options, post ProjectionEvents to its input, and it resolves exactly once into a single EventExpectationResult broadcast on its output (failures on the error port, diagnostics on the event port). It needs nothing else — no engine, registry, or runtime:

await using var node = new EventExpectationNode(new EventExpectationOptions
{
    Kind = EventExpectationNodeKind.Expect,
    Name = "order-completed",
    TimeoutMilliseconds = 5000,
    Filter = new EventFilter
    {
        Type = "operation.completed",
        Status = "ok",
        SubjectPrefix = "orders/"
    }
});

node.Output.LinkTo(asserter.Input);  // broadcast: link to as many consumers as you like

await node.Input.SendAsync(FlowMessage.Create(@event));

An Expect node is satisfied when a matching event arrives; a Guard node is satisfied when none arrives. The node resolves on the first of three triggers:

• a matching event,
• a configured timeout (armed over the injected TimeProvider),
• input completion via CompleteWithResultAsync().

Ports

The result carries the correlation id of the matching event (or, on timeout and completion, the last observed event's id) so correlation flows event → result via the FlowMessage<T> envelope.

Result

EventExpectationResult includes:

• evaluated timestamp
• expectation name
• expectation kind
• satisfied flag
• matched flag
• timeout flag
• matched event summary when one exists
• recent observed event summaries
• filter copy
• reason text

Filters

Expectations use the same neutral EventFilter contract as the Projections package (the shared ProjectionEvent / EventFilter / EventFilterMatcher contracts come from FluxFlow.Components.Projections). Filters support:

• event type or type prefix
• subject prefix
• channel prefix
• excluded subject prefix
• excluded channel prefix
• status
• source
• source node id
• component id through an event attribute named componentId
• attribute key/value pairs
• event timestamp range

Filters use ordinal string comparison.

Timing

Pass a TimeProvider to the constructor for deterministic timeout and result timestamps in tests or hosts. The timeout is armed via TimeProvider.CreateTimer, so a FakeTimeProvider drives it by advancing the clock — no real-time wait.

var node = new EventExpectationNode(options, timeProvider);

Composition

Building a workflow — reading config, creating nodes, linking them — is a separate concern from the node. This package is just the node; wire it from whatever composition/host layer you use.