---
phase: 03-round-trip-verification
plan: 01
subsystem: testing
tags: [unit-tests, crypto, compression, format, hex-literal, aes-256-cbc, hmac-sha256, sha256, gzip]

# Dependency graph
requires:
  - phase: 02-core-archiver
    provides: "crypto.rs, compression.rs, format.rs modules with full pipeline"
provides:
  - "Library crate (src/lib.rs) re-exporting all modules for integration tests"
  - "19 unit tests covering crypto, compression, and format serialization"
  - "Dev-dependencies: tempfile, assert_cmd, hex-literal, predicates"
affects: [03-02, integration-tests, round-trip-verification]

# Tech tracking
tech-stack:
  added: [hex-literal 1.1, tempfile 3.26, assert_cmd 2.1, predicates 3.1]
  patterns: [library-crate-reexports, cfg-test-modules, hex-literal-for-known-values]

key-files:
  created: [src/lib.rs]
  modified: [src/main.rs, src/crypto.rs, src/compression.rs, src/format.rs, Cargo.toml]

key-decisions:
  - "Library crate with pub mod re-exports for all 6 modules (archive, cli, compression, crypto, format, key)"
  - "hex-literal v1.1 for compile-time hex byte arrays in SHA-256 test assertions"
  - "Unit tests embedded in modules via #[cfg(test)] mod tests blocks (not separate test files)"

patterns-established:
  - "Library crate pattern: src/lib.rs re-exports, main.rs uses encrypted_archive:: imports"
  - "Test pattern: #[cfg(test)] mod tests with use super::* inside each module"
  - "SHA-256 verification against known values from FORMAT.md worked example"

requirements-completed: [TST-03]

# Metrics
duration: 3min
completed: 2026-02-24
---

# Phase 3 Plan 01: Library Crate and Unit Tests Summary

**Library crate structure with 19 unit tests covering AES-256-CBC encrypt/decrypt, HMAC-SHA256, SHA-256, gzip compression, and format serialization round-trips**

## Performance

- **Duration:** 3 min
- **Started:** 2026-02-24T21:28:18Z
- **Completed:** 2026-02-24T21:31:08Z
- **Tasks:** 2
- **Files modified:** 6

## Accomplishments
- Created library crate (src/lib.rs) enabling integration tests in tests/ directory for Plan 02
- Added 19 unit tests across 3 modules all passing: crypto (6), compression (6), format (7)
- Verified SHA-256 known values match FORMAT.md Section 12.3 worked example
- Verified TOC entry size calculation matches FORMAT.md worked example (110 + 109 = 219 bytes)

## Task Commits

Each task was committed atomically:

1. **Task 1: Create lib.rs, update main.rs imports, add dev-dependencies** - `ce9012c` (feat)
2. **Task 2: Add unit tests to crypto.rs, compression.rs, and format.rs** - `3e96b1e` (test)

## Files Created/Modified
- `src/lib.rs` - Library crate re-exporting all 6 modules as public
- `src/main.rs` - Updated to use `encrypted_archive::` imports instead of local mod declarations
- `Cargo.toml` - Added dev-dependencies (tempfile, assert_cmd, hex-literal, predicates)
- `src/crypto.rs` - 6 unit tests: encrypt/decrypt roundtrip, empty data, size formula, HMAC, SHA-256 known values
- `src/compression.rs` - 6 unit tests: compress/decompress roundtrip, empty/large data, should_compress heuristic
- `src/format.rs` - 7 unit tests: header roundtrip, TOC entry roundtrip (ASCII/Cyrillic/empty name), bad magic/version rejection, entry size calculation

## Decisions Made
- Used hex-literal v1.1 (latest) for compile-time hex byte arrays in SHA-256 assertions
- Embedded tests in modules via #[cfg(test)] rather than separate test files (keeps tests close to implementation)
- Library crate re-exports all 6 modules (archive, cli, compression, crypto, format, key) for maximum flexibility

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 3 - Blocking] Updated hex-literal version from 0.4 to 1.1**
- **Found during:** Task 2 (adding unit tests)
- **Issue:** Plan specified hex-literal 1.1 but initial Cargo.toml had 0.4; cargo resolved to 0.4.1 which is outdated
- **Fix:** Updated Cargo.toml to hex-literal = "1.1" (latest stable)
- **Files modified:** Cargo.toml
- **Verification:** cargo build + cargo test pass
- **Committed in:** 3e96b1e (Task 2 commit)

---

**Total deviations:** 1 auto-fixed (1 blocking)
**Impact on plan:** Minor version correction, no scope change.

## Issues Encountered
None

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- Library crate ready for integration tests in tests/ directory (Plan 02)
- All pipeline modules have unit test coverage proving correctness
- Dev-dependencies (tempfile, assert_cmd, predicates) ready for CLI round-trip tests

## Self-Check: PASSED

- All 6 key files exist on disk
- Both task commits verified: ce9012c, 3e96b1e
- cargo test: 19 passed, 0 failed

---
*Phase: 03-round-trip-verification*
*Completed: 2026-02-24*