explicit test assertions

Tests should explicitly assert both positive and negative expectations to make test intentions clear and prevent regressions. Use the expect syntax to specify not only what should happen, but also what should NOT happen in your tests.

When testing scenarios that should produce warnings or info messages, use expect warn or expect info. Equally important, when testing scenarios that should NOT produce these annotations, use expect no_warn or expect no_info to make this expectation explicit.

This approach serves two purposes:

1. Clarity: Future developers can immediately understand what the test is validating
2. Regression prevention: Changes that accidentally introduce or remove annotations will be caught

Example:

# Explicit about expecting a warning
eval instant at 20m irate(http_requests_histogram{path="/c"}[20m])
    expect warn
    {path="/c"} 

# Explicit about NOT expecting a warning  
eval instant at 20m irate(http_requests_histogram{path="/f"}[20m])
    expect no_warn
    {path="/f"} 

Remember: the old eval behavior always asserted no annotations, but the new behavior is more tolerant. Be explicit about your expectations to maintain test robustness.