Current Status

The EventExample integration test is currently skipped in CI.

Skip Reason

Concurrent event handlers have non-deterministic output order.

Problem Description

The EventExample demonstrates ARO's event system with multiple concurrent event handlers. When events are emitted, handlers execute in parallel via Swift's TaskGroup, resulting in:

• Non-deterministic execution order
• Output lines appearing in different orders between runs
• Platform-dependent scheduling behavior

What Must Be Done to Enable

Option 1: Use occurrence-check mode (Recommended)

• Add occurrence-check: true to test.hint
• This allows lines to appear in any order as long as all expected lines are present
• Works well for event-driven code with concurrent handlers

Option 2: Refactor to sequential execution

• Modify the example to execute handlers sequentially
• Less representative of real event-driven behavior
• Not recommended as it changes the example's purpose

Option 3: Output aggregation

• Collect all handler outputs and sort before comparing
• Requires runtime changes to aggregate event handler outputs

Option 4: Statistical testing

• Run multiple times and ensure output contains expected content
• More complex test infrastructure needed

Recommended Fix

# In Examples/EventExample/test.hint
mode: interpreter
occurrence-check: true

Then regenerate expected.txt with unique identifying lines.

Files

• Examples/EventExample/main.aro
• Examples/EventExample/test.hint
• Examples/EventExample/expected.txt

Labels

integration-test, events, concurrency