ci: add quality gates and lockfile policy guard

Author: alexander-irbis

.githooks/pre-commit

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Library repositories must not commit Cargo.lock.
+if git diff --cached --name-only | grep -Eq '(^|/)Cargo\.lock$'; then
+  echo "error: Cargo.lock must not be committed in library repositories (it should be gitignored)." >&2
+  exit 1
+fi
+
+

.github/workflows/ci.yml

@@ -0,0 +1,47 @@
+name: ci
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  policy:
+    name: policy (no Cargo.lock)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Fail if Cargo.lock is committed
+        run: |
+          set -euo pipefail
+          if git ls-files | grep -Eq '(^|/)Cargo\.lock$'; then
+            echo "error: Cargo.lock must not be committed in library repositories (it should be gitignored)." >&2
+            exit 1
+          fi
+
+  fmt:
+    name: fmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@nightly
+        with:
+          components: rustfmt
+      - name: cargo fmt (check)
+        run: cargo +nightly fmt --all -- --check
+
+  test:
+    name: check / test / clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+      - name: cargo check
+        run: cargo check --all-targets
+      - name: cargo test
+        run: cargo test
+      - name: cargo clippy
+        run: cargo clippy --all-targets -- -D warnings
+
+

README.md

@@ -19,7 +19,7 @@ Currently, Smart String is in active development, and its API might undergo chan
 tried-and-true patterns from earlier works, the library as a standalone entity is relatively new. Hence, it's advised to
 use it with caution and feel free to provide feedback, report issues, or suggest improvements.
 
-Not yet covered by tests.
+Some core behavior is covered by unit tests, but coverage is incomplete.
 
 ## Features
 
@@ -65,3 +65,20 @@ Licensed under either of
 Unless you explicitly state otherwise, any contribution intentionally submitted
 for inclusion in the work by you, as defined in the Apache-2.0 license,
 shall be dual licensed as above, without any additional terms or conditions.
+
+## Development
+
+Recommended (enable repo hooks once per clone):
+
+```bash
+git config core.hooksPath .githooks
+```
+
+Quality gates:
+
+```bash
+cargo +nightly fmt --all -- --check
+cargo check --all-targets
+cargo test
+cargo +stable clippy --all-targets -- -D warnings
+```

rustfmt.toml

@@ -0,0 +1,20 @@
+# Project configuration for rustfmt Rust code formatter.
+# See full list of configurations at:
+# https://github.com/rust-lang-nursery/rustfmt/blob/master/Configurations.md
+
+max_width = 100
+enum_discrim_align_threshold = 40
+format_strings = false
+group_imports = "StdExternalCrate"
+imports_granularity = "Item"
+
+format_code_in_doc_comments = true
+format_macro_matchers = true
+use_try_shorthand = true
+
+#error_on_line_overflow = true
+#error_on_unformatted = true
+
+unstable_features = true
+
+