# Topic Name Validation Tests Summary

## What Was Added

Successfully added 4 new property tests in the `topic_name_validation_tests` module to utilize the previously unused `validate_topic` function and the generator functions `potentially_invalid_topic()` and `aws_iot_topic()`.

### New Tests

1. **`prop_invalid_topic_rejection`**
   - Uses the `potentially_invalid_topic()` generator
   - Tests validation of potentially invalid topics
   - Discovered that empty topics are actually valid in MQTT (for will messages)
   - Validates that null characters and oversized topics are properly rejected

2. **`prop_topic_name_no_wildcards`**
   - Tests that topic names (for publishing) cannot contain wildcards
   - Uses `topic_filter_with_wildcards()` to generate topics with wildcards
   - Ensures wildcards `+` and `#` are rejected in topic names

3. **`prop_valid_topic_acceptance`**
   - Generates valid topic names and ensures they're accepted
   - Tests multi-level topics within size limits

4. **`prop_system_topic_validation`**
   - Uses the `aws_iot_topic()` generator
   - Tests that system topics starting with `$` are valid MQTT topics
   - Note: Application-specific restrictions are separate from MQTT validity

## Key Findings

1. **Empty topics are valid** - The code comment states "Empty topic is actually valid in MQTT (e.g., for will messages)"
2. **Topic names vs filters** - Different validation rules apply:
   - Topic names: No wildcards allowed
   - Topic filters: Can contain wildcards, stricter about empty levels
3. **Inconsistency found** - The error message in `validate_topic` mentions "empty topic" as an error, but `is_valid_topic` allows empty topics

## Impact

- The `validate_topic` import is now used, eliminating the unused import warning
- All generator functions are now utilized in tests
- Better test coverage for topic name validation (separate from topic filter validation)
- All 4 new tests pass successfully

## Existing Edge Cases

The 4 pre-existing test failures remain and are documented in PROPERTY_TEST_FINDINGS.md:
- AWS IoT length limits not enforced
- AWS reserved topics not restricted
- Empty topic levels accepted (e.g., `/topic` or `topic/`)
- Dollar-prefix edge case (`$/invalid`) accepted

These are validation bugs that should be fixed in the implementation, not test issues.