feat: lint commit message from hash range

[JustBipin]

Adds --from-hash and --to-hash flags to lint all commit messages between two commits, inclusive.

Usage

cocox --from-hash <hash>              # from <hash> to HEAD
cocox --from-hash <hash> --to-hash <hash>   # explicit range

Feature

• --from-hash and --to-hash flags added to the CLI
• --to-hash defaults to HEAD when not provided
• --to-hash requires --from-hash and is mutually exclusive with message, --file, and --hash
• src/git_helpers.rs: added get_commit_messages_from_hash_range() which fetches all commit messages in the range and prepends the from commit separately, since A..B in git excludes A

Test infrastructure

• tests/common/git_repo.rs: introduces TestRepo, a temporary git repo with minimal config for use in integration tests
  • TestRepo::new() switches the process working directory into the temp repo
  • Drop restores the original working directory when TestRepo goes out of scope
  • A static Mutex is acquired on construction and released on drop, serializing all tests that use TestRepo to prevent race conditions on the process-global cwd
• serial_test = "3" added as a dev-dependency
• Unit tests in src/git_helpers.rs that depended on the project repo's own git history replaced with integration tests in tests/git_helpers.rs using TestRepo, so tests are self-contained and repo-state independent

Integration tests added

• tests/git_helpers.rs: full coverage of get_commit_message_from_hash and get_commit_messages_from_hash_range with known commit messages
• tests/cli.rs: success and failure cases for --hash (exact hash, invalid message, ignored message) and --from-hash/--to-hash (invalid commit at from, middle, and to positions; ignored commits in range; single-commit range)
• tests/cli.rs: extended mutual exclusion tests covering all missing argument combinations (message + --hash, message + --from-hash, --hash + --from-hash, --to-hash with non---from-hash inputs)

TestCoverage: 97%

closes #10
closes #12
closes #16

[sugat009]

Comprehensive review

Reviewed across code quality, architecture, performance, tests, docs, Rust idioms, and CI/CD. Findings below use Conventional Comments. Inline comments below cover the diff-anchored items; this top-level body covers findings that span multiple files or touch code outside the PR's diff.

General findings (not anchored to specific diff lines)

issue (blocking) — cargo fmt --check exits 1 with 22 unformatted hunks (mostly trailing whitespace in tests/cli.rs). cargo clippy --all-targets -- -D warnings exits 101 with 4 needless_return errors at src/linter.rs:13, src/utils.rs:14, src/utils.rs:18, src/main.rs:15. CI doesn't gate either tool today, so the regression slipped in unnoticed. One cleanup commit + adding both gates to .github/workflows/ci.yml closes both.

suggestion — src/linter.rs:12 and src/utils.rs:8 (not modified by this PR but exercised heavily by it): Regex::new(&pattern).unwrap() runs per call. Measured locally: ~80 µs/call for the linter regex, ~280 µs/call for the 9 ignore patterns — combined ~360 µs/commit. For a range of 10k commits that's ~3.6 s of pure regex compilation. Cache via std::sync::LazyLock<Regex> (stable since 1.80) — ~3000× speedup for ~10 lines. Highest-ROI fix on the perf axis.

suggestion — README.md has no mention of --hash, --from-hash, or --to-hash. The only documentation for the new feature is this PR body, which becomes invisible after merge. Three lines under a "Usage" section would meaningfully improve discoverability.

suggestion — many test assertions in tests/cli.rs use predicate::str::contains("Commit validation: successful!") where exact match would be more protective. The success message is a static constant; substring match weakens regression coverage. Future per-commit logging (per the TODO inline below) could silently start passing through these.

question — is the --no-merges filter intentional and meant to deviate from Python upstream? (See inline issue at src/git_helpers.rs:28.)

nitpick — PR body uses closes: #10, #12. The colon may not be recognized by GitHub's auto-close keyword parser. Standard form: Closes #10 on its own line (or paragraph), one per line. Worth checking the auto-link rendering before relying on it.

nitpick — uninlined_format_args clippy lint applies throughout src/command.rs and src/git_helpers.rs. Rust 2021+ supports format!("hash {commit_hash}") instead of format!("hash {}", commit_hash).

nitpick — commit subject typos that will land in CHANGELOG.md if not squash-merged with the (clean) PR title:

• addd (commit 2060aba) → add
• constrain (same commit) → constraint
• projecet (commit 0f980d7 body) → project

👏 Praise

praise — TestRepo is a real contribution. It correctly identifies the cwd-mutation problem and applies a working serialization solution; using it as a fixture-commit factory is exactly what was needed to close #10. Once the run_git exit-code check and the mutex-poison handling are in, it'll be genuinely strong test infrastructure.

praise — the mutual-exclusion test matrix is thorough: 7 new pairs in tests/cli.rs plus the --to-hash-without---from-hash case. Closes #12 cleanly and goes beyond what the issue asked for.

---

Inline comments follow on specific lines. Happy to file any of the blocking items as standalone tickets if helpful.

[sugat009]

Escalating my prior comment-level review to formally request changes. The blocking items from that review still stand:

1. tests/common/git_repo.rs:57-63 — run_git swallows non-zero git exits, which silently breaks the range_errors_on_unknown_to_hash test
2. src/command.rs:51 — range mode prints no per-commit failure attribution (the // TODO)
3. cargo fmt --check and cargo clippy -- -D warnings both fail today

The non-blocking issues, suggestions, questions, and nitpicks from the prior review are all in scope but won't gate merge. Inline comments from the prior review remain attached.

[JustBipin]

All blockingissues and most of the suggestions have been implemented. The ones which are't implemented are either reserved for future Pr, or for further discussions.

We will have configurations for detailed logs for cocox, for the time being , i have placed home println!() and eprintln!().

Output Examples

Single Valid Commit:

========= Linting Message:: feat: add new feature ===========
Commit validation: successful!

Ignored Commit:

========= Linting Message:: Initial commit ===========
commit message ignored, skipping lint

Hash Range (Batch):

========= Linting Message:: feat: feature A ===========
lint success

========= Linting Message:: Merge pull request #1 ===========
commit message ignored, skipping lint

Commit validation: successful!

[JustBipin]

The changes in this PR have definitely grown way beyond what's described in the PR description. All the changes are properly committed, following the convention. Please use those for the description when squashing them.

[aj3sh]

What is this for?

[JustBipin]

it's a place holder for detialed logs. Is it ok to just a println!() for this pr? future PR with configuration for detialed logs will be made.

[aj3sh]

Why are we going to show the funny logs to the user? Please refer to commitlint for the output format.

[JustBipin]

I'll just remove all the logs for now.

[aj3sh]

These are the debug logs, do not redirect them to stdout directly. Lets remove them for now, and plan the debug logging for the future.

[JustBipin]

Great, I'll remove them.

[aj3sh]

I really appreciate the effort here. The code looks awesome. I have added few suggestions for the debug logs and the tests. The PR contains the big feature, so the delay in the review is expected 😀.