feat: support linting from the last tag

Author: benquarmby

@commitlint/cli/src/cli.test.ts

@@ -548,6 +548,7 @@ test('should print help', async () => {
 		  -x, --extends        array of shareable configurations to extend  [array]
 		  -H, --help-url       help url in error message  [string]
 		  -f, --from           lower end of the commit range to lint; applies if edit=false  [string]
+		      --from-last-tag  uses the last tag as the lower end of the commit range to lint; applies if edit=false and from is not set  [boolean]
 		      --git-log-args   additional git log arguments as space separated string, example '--first-parent --cherry-pick'  [string]
 		  -l, --last           just analyze the last commit; applies if edit=false  [boolean]
 		  -o, --format         output format of the results  [string]

@commitlint/cli/src/cli.ts

@@ -90,6 +90,11 @@ const cli = yargs(process.argv.slice(2))
 				'lower end of the commit range to lint; applies if edit=false',
 			type: 'string',
 		},
+		'from-last-tag': {
+			description:
+				'uses the last tag as the lower end of the commit range to lint; applies if edit=false and from is not set',
+			type: 'boolean',
+		},
 		'git-log-args': {
 			description:
 				"additional git log arguments as space separated string, example '--first-parent --cherry-pick'",
@@ -242,6 +247,7 @@ async function main(args: MainArgs): Promise<void> {
 		: read({
 				to: flags.to,
 				from: flags.from,
+				fromLastTag: flags['from-last-tag'],
 				last: flags.last,
 				edit: flags.edit,
 				cwd: flags.cwd,
@@ -400,6 +406,7 @@ function checkFromEdit(flags: CliFlags): boolean {
 function checkFromHistory(flags: CliFlags): boolean {
 	return (
 		typeof flags.from === 'string' ||
+		typeof flags['from-last-tag'] === 'boolean' ||
 		typeof flags.to === 'string' ||
 		typeof flags.last === 'boolean'
 	);

@commitlint/cli/src/types.ts

@@ -8,6 +8,7 @@ export interface CliFlags {
 	help?: boolean;
 	'help-url'?: string;
 	from?: string;
+	'from-last-tag'?: boolean;
 	'git-log-args'?: string;
 	last?: boolean;
 	format?: string;

@commitlint/read/src/read.test.ts

@@ -84,3 +84,49 @@ test('should only read the last commit', async () => {
 
 	expect(result).toEqual(['commit X']);
 });
+
+test('should read commits from the last annotated tag', async () => {
+	const cwd: string = await git.bootstrap();
+
+	await execa(
+		'git',
+		['commit', '--allow-empty', '-m', 'chore: release v1.0.0'],
+		{cwd}
+	);
+	await execa('git', ['tag', 'v1.0.0', '--annotate', '-m', 'v1.0.0'], {cwd});
+	await execa('git', ['commit', '--allow-empty', '-m', 'commit 1'], {cwd});
+	await execa('git', ['commit', '--allow-empty', '-m', 'commit 2'], {cwd});
+
+	const result = await read({cwd, fromLastTag: true});
+
+	expect(result).toEqual(['commit 2\n\n', 'commit 1\n\n']);
+});
+
+test('should read commits from the last lightweight tag', async () => {
+	const cwd: string = await git.bootstrap();
+
+	await execa(
+		'git',
+		['commit', '--allow-empty', '-m', 'chore: release v9.9.9-alpha.1'],
+		{cwd}
+	);
+	await execa('git', ['tag', 'v9.9.9-alpha.1'], {cwd});
+	await execa('git', ['commit', '--allow-empty', '-m', 'commit A'], {cwd});
+	await execa('git', ['commit', '--allow-empty', '-m', 'commit B'], {cwd});
+
+	const result = await read({cwd, fromLastTag: true});
+
+	expect(result).toEqual(['commit B\n\n', 'commit A\n\n']);
+});
+
+test('should not read any commits when there are no tags', async () => {
+	const cwd: string = await git.bootstrap();
+
+	await execa('git', ['commit', '--allow-empty', '-m', 'commit 7'], {cwd});
+	await execa('git', ['commit', '--allow-empty', '-m', 'commit 8'], {cwd});
+	await execa('git', ['commit', '--allow-empty', '-m', 'commit 9'], {cwd});
+
+	const result = await read({cwd, fromLastTag: true});
+
+	expect(result).toHaveLength(0);
+});

@commitlint/read/src/read.ts

@@ -9,6 +9,7 @@ import {execa} from 'execa';
 interface GetCommitMessageOptions {
 	cwd?: string;
 	from?: string;
+	fromLastTag?: boolean;
 	to?: string;
 	last?: boolean;
 	edit?: boolean | string;
@@ -19,7 +20,8 @@ interface GetCommitMessageOptions {
 export default async function getCommitMessages(
 	settings: GetCommitMessageOptions
 ): Promise<string[]> {
-	const {cwd, from, to, last, edit, gitLogArgs} = settings;
+	const {cwd, fromLastTag, to, last, edit, gitLogArgs} = settings;
+	let from = settings.from;
 
 	if (edit) {
 		return getEditCommit(cwd, edit);
@@ -38,6 +40,34 @@ export default async function getCommitMessages(
 		return [output];
 	}
 
+	if (!from && fromLastTag) {
+		const {stdout} = await execa(
+			'git',
+			[
+				'describe',
+				'--abbrev=40',
+				'--always',
+				'--first-parent',
+				'--long',
+				'--tags',
+			],
+			{cwd}
+		);
+
+		if (stdout.length === 40) {
+			// Hash only means no last tag. Use that as the from ref which
+			// results in a no-op.
+			from = stdout;
+		} else {
+			// Description will be in the format: <tag>-<count>-g<hash>
+			// Example: v3.2.0-11-g9057371a52adaae5180d93fe4d0bb808d874b9fb
+			// Minus zero based (1), dash (1), "g" prefix (1), hash (40) = -43
+			const tagSlice = stdout.lastIndexOf('-', stdout.length - 43);
+
+			from = stdout.slice(0, tagSlice);
+		}
+	}
+
 	let gitOptions: GitOptions = {from, to};
 	if (gitLogArgs) {
 		gitOptions = {

docs/reference/cli.md

@@ -22,6 +22,8 @@ Options:
   -H, --help-url       help url in error message                        [string]
   -f, --from           lower end of the commit range to lint; applies if
                        edit=false                                       [string]
+      --from-last-tag  uses the last tag as the lower end of the commit range to
+                       lint; applies if edit=false and from is not set [boolean]
       --git-log-args   additional git log arguments as space separated string,
                        example '--first-parent --cherry-pick'           [string]
   -l, --last           just analyze the last commit; applies if edit=false