TypeScript - Add overload for ReadonlyArray (#7)

ajafff · sindresorhus · commit f789ce58d5b5 · 2019-04-07T17:09:57.000+07:00
diff --git a/index.d.ts b/index.d.ts
@@ -26,6 +26,8 @@ arrify(undefined);
 declare function arrify(value: null | undefined): [];
 declare function arrify(value: string): [string];
 declare function arrify<ValueType>(value: ValueType[]): ValueType[];
+// TODO: Use 'readonly ValueType[]' in the next major version
+declare function arrify<ValueType>(value: ReadonlyArray<ValueType>): ReadonlyArray<ValueType>;
 declare function arrify<ValueType>(value: Iterable<ValueType>): ValueType[];
 declare function arrify<ValueType>(value: ValueType): [ValueType];
 
diff --git a/index.test-d.ts b/index.test-d.ts
@@ -1,4 +1,4 @@
-import {expectType} from 'tsd';
+import {expectType, expectError} from 'tsd';
 import arrify = require('.');
 
 expectType<[]>(arrify(null));
@@ -12,3 +12,4 @@ expectType<([string | number, string | number])[]>(
 	arrify(new Map<string | number, string | number>([[1, 2], ['a', 'b']]))
 );
 expectType<number[]>(arrify(new Set([1, 2])));
+expectError(arrify(['🦄'] as const).push(''));
