feat(config): support detecting config from project manifest (#571)

* feat(config): support detecting config from project manifest

* refactor: apply clippy suggestions

* test(fixture): add fixture for configuring from Cargo.toml

.github/fixtures/test-configure-from-cargo-toml/Cargo.toml

@@ -0,0 +1,39 @@
+[package]
+name = "test"
+version = "0.1.0"
+edition = "2021"
+
+[package.metadata.git-cliff.changelog]
+# changelog header
+header = """
+# Changelog\n
+All notable changes to this project will be documented in this file.\n
+"""
+# template for the changelog body
+# https://keats.github.io/tera/docs/#introduction
+body = """
+{% if version %}\
+    ## [{{ version | trim_start_matches(pat="v") }}] - {{ timestamp | date(format="%Y-%m-%d") }}
+{% else %}\
+    ## [unreleased]
+{% endif %}\
+{% for group, commits in commits | group_by(attribute="group") %}
+    ### {{ group | upper_first }}
+    {% for commit in commits %}
+        - {{ commit.message | upper_first }}\
+    {% endfor %}
+{% endfor %}\n
+"""
+# template for the changelog footer
+footer = """
+<!-- generated by git-cliff -->
+"""
+# remove the leading and trailing whitespace from the templates
+trim = true
+
+[package.metadata.git-cliff.git]
+# regex for parsing and grouping commits
+commit_parsers = [
+    { message = "^feat", group = "Features", default_scope = "app" },
+    { message = "^fix", group = "Bug Fixes", scope = "cli" },
+]

.github/fixtures/test-configure-from-cargo-toml/commit.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+set -e
+
+GIT_COMMITTER_DATE="2022-04-06 01:25:08" git commit --allow-empty -m "Initial commit"
+GIT_COMMITTER_DATE="2022-04-06 01:25:09" git commit --allow-empty -m "feat: add feature 1"
+GIT_COMMITTER_DATE="2022-04-06 01:25:10" git commit --allow-empty -m "fix: fix feature 1"
+git tag v0.1.0
+GIT_COMMITTER_DATE="2022-04-06 01:25:11" git commit --allow-empty -m "feat(gui): add feature 2"
+GIT_COMMITTER_DATE="2022-04-06 01:25:12" git commit --allow-empty -m "fix(gui): fix feature 2"
+git tag v0.2.0
+GIT_COMMITTER_DATE="2022-04-06 01:25:13" git commit --allow-empty -m "test: add tests"

.github/fixtures/test-configure-from-cargo-toml/expected.md

@@ -0,0 +1,31 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+## [unreleased]
+
+### Test
+
+- Add tests
+
+## [0.2.0] - 2022-04-06
+
+### Bug Fixes
+
+- Fix feature 2
+
+### Features
+
+- Add feature 2
+
+## [0.1.0] - 2022-04-06
+
+### Bug Fixes
+
+- Fix feature 1
+
+### Features
+
+- Add feature 1
+
+<!-- generated by git-cliff -->

.github/workflows/test-fixtures.yml

@@ -67,6 +67,7 @@ jobs:
             command: --no-exec
           - fixtures-name: test-custom-tag-pattern
             command: --tag-pattern "alpha.*"
+          - fixtures-name: test-configure-from-cargo-toml
     steps:
       - name: Checkout
         uses: actions/checkout@v4

git-cliff-core/Cargo.toml

@@ -34,6 +34,7 @@ regex.workspace = true
 log.workspace = true
 secrecy.workspace = true
 dirs.workspace = true
+lazy_static.workspace = true
 thiserror = "1.0.58"
 serde = { version = "1.0.197", features = ["derive"] }
 serde_json = "1.0.114"

git-cliff-core/src/config.rs

@@ -9,17 +9,42 @@ use serde::{
 	Deserialize,
 	Serialize,
 };
-use std::ffi::OsStr;
 use std::fmt;
 use std::fs;
 use std::path::Path;
+use std::path::PathBuf;
 
-/// Regex for matching the metadata in Cargo.toml
-const CARGO_METADATA_REGEX: &str =
-	r"^\[(?:workspace|package)\.metadata\.git\-cliff\.";
+/// Manifest file information and regex for matching contents.
+#[derive(Debug)]
+struct ManifestInfo {
+	/// Path of the manifest.
+	path:  PathBuf,
+	/// Regular expression for matching metadata in the manifest.
+	regex: Regex,
+}
+
+lazy_static::lazy_static! {
+	/// Array containing manifest information for Rust and Python projects.
+	static ref MANIFEST_INFO: Vec<ManifestInfo> = vec![
+		ManifestInfo {
+			path: PathBuf::from("Cargo.toml"),
+			regex: RegexBuilder::new(
+				r"^\[(?:workspace|package)\.metadata\.git\-cliff\.",
+			)
+			.multi_line(true)
+			.build()
+			.expect("failed to build regex"),
+		},
+		ManifestInfo {
+			path: PathBuf::from("pyproject.toml"),
+			regex: RegexBuilder::new(r"^\[(?:tool)\.git\-cliff\.")
+				.multi_line(true)
+				.build()
+				.expect("failed to build regex"),
+		},
+	];
 
-/// Regex for matching the metadata in pyproject.toml
-const PYPROJECT_METADATA_REGEX: &str = r"^\[(?:tool)\.git\-cliff\.";
+}
 
 /// Configuration values.
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -232,30 +257,46 @@ pub struct LinkParser {
 }
 
 impl Config {
+	/// Reads the config file contents from project manifest (e.g. Cargo.toml,
+	/// pyproject.toml)
+	pub fn read_from_manifest() -> Result<Option<String>> {
+		for info in (*MANIFEST_INFO).iter() {
+			if info.path.exists() {
+				let contents = fs::read_to_string(&info.path)?;
+				if info.regex.is_match(&contents) {
+					return Ok(Some(
+						info.regex.replace_all(&contents, "[").to_string(),
+					));
+				}
+			}
+		}
+		Ok(None)
+	}
+
+	/// Parses the config file from string and returns the values.
+	pub fn parse_from_str(contents: &str) -> Result<Config> {
+		Ok(config::Config::builder()
+			.add_source(config::File::from_str(contents, config::FileFormat::Toml))
+			.add_source(
+				config::Environment::with_prefix("GIT_CLIFF").separator("__"),
+			)
+			.build()?
+			.try_deserialize()?)
+	}
+
 	/// Parses the config file and returns the values.
 	pub fn parse(path: &Path) -> Result<Config> {
-		let config_builder = if path.file_name() == Some(OsStr::new("Cargo.toml")) ||
-			path.file_name() == Some(OsStr::new("pyproject.toml"))
+		if MANIFEST_INFO
+			.iter()
+			.any(|v| path.file_name() == v.path.file_name())
 		{
-			let contents = fs::read_to_string(path)?;
-			let metadata_regex = RegexBuilder::new(
-				if path.file_name() == Some(OsStr::new("Cargo.toml")) {
-					CARGO_METADATA_REGEX
-				} else {
-					PYPROJECT_METADATA_REGEX
-				},
-			)
-			.multi_line(true)
-			.build()?;
-			let contents = metadata_regex.replace_all(&contents, "[");
-			config::Config::builder().add_source(config::File::from_str(
-				&contents,
-				config::FileFormat::Toml,
-			))
-		} else {
-			config::Config::builder().add_source(config::File::from(path))
-		};
-		Ok(config_builder
+			if let Some(contents) = Self::read_from_manifest()? {
+				return Self::parse_from_str(&contents);
+			}
+		}
+
+		Ok(config::Config::builder()
+			.add_source(config::File::from(path))
 			.add_source(
 				config::Environment::with_prefix("GIT_CLIFF").separator("__"),
 			)
@@ -269,7 +310,6 @@ mod test {
 	use super::*;
 	use pretty_assertions::assert_eq;
 	use std::env;
-	use std::path::PathBuf;
 	#[test]
 	fn parse_config() -> Result<()> {
 		let path = PathBuf::from(env!("CARGO_MANIFEST_DIR"))

git-cliff/src/lib.rs

@@ -347,6 +347,8 @@ pub fn run(mut args: Opt) -> Result<()> {
 		config
 	} else if path.exists() {
 		Config::parse(&path)?
+	} else if let Some(contents) = Config::read_from_manifest()? {
+		Config::parse_from_str(&contents)?
 	} else {
 		if !args.context {
 			warn!(