From 4d4ec180e76e28322c0d2086cc489359365b45cf Mon Sep 17 00:00:00 2001
From: Hiroki Osame <hiroki.osame@gmail.com>
Date: Thu, 20 Jun 2024 14:13:07 +0900
Subject: [PATCH] fix: disallow accepting aliases with -- BREAKING CHANGE: no
 longer supports the edge-case --a where a is an alias

---
 src/type-flag.ts         |  4 +++-
 tests/specs/type-flag.ts | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/type-flag.ts b/src/type-flag.ts
index be9e339..915d532 100644
--- a/src/type-flag.ts
+++ b/src/type-flag.ts
@@ -56,7 +56,9 @@ export const typeFlag = <Schemas extends Flags>(
 
 	argvIterator(argv, {
 		onFlag(name, explicitValue, flagIndex) {
-			const isKnownFlag = hasOwn(flagRegistry, name);
+			const isAlias = flagIndex.length === 3;
+			const isValid = isAlias || name.length > 1;
+			const isKnownFlag = isValid && hasOwn(flagRegistry, name);
 			if (
 				ignore?.(
 					isKnownFlag ? KNOWN_FLAG : UNKNOWN_FLAG,
diff --git a/tests/specs/type-flag.ts b/tests/specs/type-flag.ts
index 6534f64..d5e51c8 100644
--- a/tests/specs/type-flag.ts
+++ b/tests/specs/type-flag.ts
@@ -406,6 +406,23 @@ export default testSuite(({ describe }) => {
 					expect<string[]>(parsed.flags.alias).toStrictEqual(['', '', 'value']);
 					expect(argv).toStrictEqual([]);
 				});
+
+				test('should not accept aliases with --', () => {
+					const argv = ['--a'];
+					const parsed = typeFlag(
+						{
+							alias: {
+								type: Boolean,
+								alias: 'a',
+							},
+						},
+						argv,
+					);
+
+					expect<string | undefined>(parsed.flags.alias).toBe(undefined);
+					expect<(string | boolean)[]>(parsed.unknownFlags.a).toStrictEqual([true]);
+					expect(argv).toStrictEqual([]);
+				});
 			});
 
 			test('unknown flags', () => {