Check if yarn.lock is ignored before throwing error (#582)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

source/git-util.js

@@ -226,3 +226,18 @@ exports.verifyRecentGitVersion = async () => {
 
 	verifyRequirementSatisfied('git', installedVersion);
 };
+
+exports.checkIfFileGitIgnored = async pathToFile => {
+	try {
+		const {stdout} = await execa('git', ['check-ignore', pathToFile]);
+		return Boolean(stdout);
+	} catch (error) {
+		// If file is not ignored, `git check-ignore` throws an empty error and exits.
+		// Check that and return false so as not to throw an unwanted error.
+		if (error.stdout === '' && error.stderr === '') {
+			return false;
+		}
+
+		throw error;
+	}
+};

source/index.js

@@ -128,15 +128,21 @@ module.exports = async (input = 'patch', options) => {
 			{
 				title: 'Installing dependencies using Yarn',
 				enabled: () => options.yarn === true,
-				task: () => exec('yarn', ['install', '--frozen-lockfile', '--production=false']).pipe(
-					catchError(error => {
-						if (error.stderr.startsWith('error Your lockfile needs to be updated')) {
-							return throwError(new Error('yarn.lock file is outdated. Run yarn, commit the updated lockfile and try again.'));
-						}
+				task: () => {
+					return exec('yarn', ['install', '--frozen-lockfile', '--production=false']).pipe(
+						catchError(async error => {
+							if ((!error.stderr.startsWith('error Your lockfile needs to be updated'))) {
+								return;
+							}
 
-						return throwError(error);
-					})
-				)
+							if (await git.checkIfFileGitIgnored('yarn.lock')) {
+								return;
+							}
+
+							throw new Error('yarn.lock file is outdated. Run yarn, commit the updated lockfile and try again.');
+						})
+					);
+				}
 			},
 			{
 				title: 'Installing dependencies using npm',