feat: edit flag now accepts the path to the commit file

Closes conventional-changelog#40.

Author: satazor

@commitlint/core/src/read.js

@@ -19,7 +19,7 @@ async function getCommitMessages(settings) {
 	const {cwd, from, to, edit} = settings;
 
 	if (edit) {
-		return getEditCommit(cwd);
+		return getEditCommit(cwd, edit);
 	}
 
 	if (await isShallow(cwd)) {
@@ -57,15 +57,19 @@ async function isShallow(cwd) {
 }
 
 // Get recently edited commit message
-// (cwd: string) => Promise<Array<String>>
-async function getEditCommit(cwd) {
+// (cwd: string, edit: any) => Promise<Array<String>>
+async function getEditCommit(cwd, edit) {
 	const top = await toplevel(cwd);
 
 	if (typeof top !== 'string') {
 		throw new TypeError(`Could not find git root from ${cwd}`);
 	}
 
-	const editFilePath = path.join(top, '.git/COMMIT_EDITMSG');
+	const editFilePath =
+		typeof edit === 'string'
+			? path.resolve(top, edit)
+			: path.join(top, '.git/COMMIT_EDITMSG');
+
 	const editFile = await sander.readFile(editFilePath);
 	return [`${editFile.toString('utf-8')}\n`];
 }

@commitlint/core/src/read.test.js

@@ -6,6 +6,16 @@ import * as sander from '@marionebl/sander';
 import pkg from '../package';
 import read from './read';
 
+test('get edit commit message specified by the `edit` flag', async t => {
+	const cwd = await git.bootstrap();
+
+	await sander.writeFile(cwd, 'commit-msg-file', 'foo');
+
+	const expected = ['foo\n'];
+	const actual = await read({edit: 'commit-msg-file', cwd});
+	t.deepEqual(actual, expected);
+});
+
 test('get edit commit message from git root', async t => {
 	const cwd = await git.bootstrap();