From ebb32b156755bee0b7f6efe25fcf22bce524fb70 Mon Sep 17 00:00:00 2001
From: Luke Bennett <hello@lukebennett.com.au>
Date: Fri, 19 Aug 2022 13:24:12 +1000
Subject: [PATCH] Handle readonly arrays for `isNonEmptyArray` guard.

---
 .changeset/olive-dryers-destroy.md | 5 +++++
 src/guards.test.ts                 | 2 ++
 src/guards.ts                      | 2 +-
 3 files changed, 8 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/olive-dryers-destroy.md

diff --git a/.changeset/olive-dryers-destroy.md b/.changeset/olive-dryers-destroy.md
new file mode 100644
index 0000000..cc31eaf
--- /dev/null
+++ b/.changeset/olive-dryers-destroy.md
@@ -0,0 +1,5 @@
+---
+'emery': patch
+---
+
+Handle readonly arrays for `isNonEmptyArray` guard.
diff --git a/src/guards.test.ts b/src/guards.test.ts
index 246ab9a..e2ab57a 100644
--- a/src/guards.test.ts
+++ b/src/guards.test.ts
@@ -65,7 +65,9 @@ describe('guards', () => {
   describe('array', () => {
     it('isNonEmptyArray should validate assumed values', () => {
       expect(isNonEmptyArray([1, 2])).toBe(true);
+      expect(isNonEmptyArray([1, 2] as const)).toBe(true);
       expect(isNonEmptyArray([])).toBe(false);
+      expect(isNonEmptyArray([] as const)).toBe(false);
     });
   });
 
diff --git a/src/guards.ts b/src/guards.ts
index 20784ef..257a0e9 100644
--- a/src/guards.ts
+++ b/src/guards.ts
@@ -33,7 +33,7 @@ export function isUndefined(value: unknown): value is undefined {
 // ------------------------------
 
 /** Checks whether or not an array is empty. */
-export function isNonEmptyArray<T>(value: T[]): value is [T, ...T[]] {
+export function isNonEmptyArray<T>(value: readonly T[]): value is [T, ...T[]] {
   return value.length > 0;
 }