fix: default maxArgLength to undefined instead of NaN when parsing cli args

Author: iiroj

.changeset/pretty-roses-check.md

@@ -0,0 +1,5 @@
+---
+'lint-staged': patch
+---
+
+Correctly set the `--max-arg-length` default value based on the running platform. This controls how very long lists of staged files are split into multiple chunks.

lib/cli.js

@@ -167,6 +167,15 @@ export const parseCliOptions = (argv) => {
     values['hide-unstaged'] = false // becomes redundant
   }
 
+  const maxArgLength =
+    values['max-arg-length'] !== undefined ? parseInt(values['max-arg-length'], 10) : undefined
+
+  if (Number.isNaN(maxArgLength)) {
+    throw new TypeError(`Option '--mar-arg-length' takes a numeric argument`, {
+      cause: { '--max-arg-length': values['max-arg-length'] },
+    })
+  }
+
   return {
     allowEmpty: values['allow-empty'] ?? false,
     concurrent: values.concurrent === undefined ? true : JSON.parse(values.concurrent),
@@ -181,7 +190,7 @@ export const parseCliOptions = (argv) => {
     hidePartiallyStaged: values['hide-partially-staged'] ?? true,
     hideUnstaged: !!values['hide-unstaged'],
     hideAll: !!values['hide-all'],
-    maxArgLength: parseInt(values['max-arg-length'], 10),
+    maxArgLength,
     quiet: !!values.quiet,
     relative: !!values.relative,
     revert: values.revert ?? true,

test/unit/cli.spec.js

@@ -23,7 +23,7 @@ suite('cli', () => {
         hidePartiallyStaged: true,
         hideUnstaged: false,
         hideAll: false,
-        maxArgLength: NaN,
+        maxArgLength: undefined,
         quiet: false,
         relative: false,
         revert: true,
@@ -78,7 +78,19 @@ suite('cli', () => {
       expect(options.concurrent).toBe(10)
     })
 
-    it('should parse max-arg-length option', ({ expect }) => {
+    it('should throw when using max-arg-length without value', ({ expect }) => {
+      expect(() => parseCliOptions(['--max-arg-length'])).toThrow(
+        `Option '--max-arg-length <value>' argument missing`
+      )
+    })
+
+    it('should throw when using max-arg-length with non-numeric value', ({ expect }) => {
+      expect(() => parseCliOptions(['--max-arg-length=test'])).toThrow(
+        `Option '--mar-arg-length' takes a numeric argument`
+      )
+    })
+
+    it('should parse max-arg-length option as integer', ({ expect }) => {
       const options = parseCliOptions(['--max-arg-length=100'])
       expect(options.maxArgLength).toBe(100)
     })