Fix npm pack JSON parsing when lifecycle scripts output to stdout

The --foreground-scripts=false flag doesn't prevent user scripts from writing directly to stdout. For example, Husky's prepare script can output text that pollutes the JSON output from npm pack --json, causing parsing failures.

Author: sindresorhus

source/npm/util.js

@@ -192,7 +192,11 @@ export const getFilesToBePacked = async rootDirectory => {
 	], {cwd: rootDirectory});
 
 	try {
-		const {files} = JSON.parse(stdout).at(0);
+		// HACK: NPM lifecycle scripts can output text even with --silent and --foreground-scripts=false.
+		// For example, Husky's prepare script outputs "> package@version prepare" and "> husky install".
+		// We extract only the JSON portion by finding the first '[' character.
+		// Related: https://github.com/sindresorhus/np/issues/742
+		const {files} = JSON.parse(stdout.slice(Math.max(0, stdout.indexOf('[')))).at(0);
 		return files.map(file => file.path);
 	} catch (error) {
 		throw new Error('Failed to parse output of npm pack', {cause: error});

test/fixtures/files/prepare-script/index.js

@@ -0,0 +1,3 @@
+export default function foo() {
+	return 'bar';
+}

test/fixtures/files/prepare-script/package.json

@@ -0,0 +1,8 @@
+{
+	"name": "foo",
+	"version": "0.0.0",
+	"files": ["index.js"],
+	"scripts": {
+		"prepare": "echo '> foo@0.0.0 prepare' && echo '> test prepare script'"
+	}
+}

test/npm/util/packed-files.js

@@ -71,3 +71,6 @@ test('doesn\'t show files in .github', verifyPackedFiles, 'dot-github', [
 	'index.js',
 ]);
 
+test('handles prepare script output (e.g., Husky)', verifyPackedFiles, 'prepare-script', [
+	'index.js',
+]);