# Test Case: zstd Compression Level 15

**Test ID**: TC106-zstd-level15  

**G5 fixture contract**: Use [G5-MANUAL-SETUP.md](G5-MANUAL-SETUP.md).
Its generated paths, source comparisons, structured corruption offsets, and
cleanup rules supersede placeholder examples in this file.
**Category**: Compression  
**Priority**: High  
**Regression**: None

## Objective
Verify zstd compressed data path with level 15 (high) compression.

## Preconditions
- EROFS image created with zstd level 15: `mkfs.erofs -zzstd,level=15 test.img src/`
- Large test files for compression testing
- FreeBSD 13.0+ with libzstd

## Test Steps
1. Create image with zstd level 15 compression
2. Attach and mount: `unit=$(mdconfig -a -t vnode -f test.img); mount -t erofs -o ro /dev/${unit} /mnt`
3. Read all test files
4. Verify content integrity
5. Test partial reads

## Expected Results
- All files decompress correctly
- Better compression than level 1
- Decompression still fast
- No memory issues

## Verification Method
- All checksums match
- Compression ratio > zstd level 1
- Decompression works for all files
- Random access validated

## Cleanup
```sh
umount /mnt
mdconfig -d -u "${unit}"
```

## Notes
Tests feature 59: zstd compressed data path with high compression.