From 8376e2dbcd38697ce62615d9a539fd198fbc4713 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Aura=20Rom=C3=A1n?= <kyradiscord@gmail.com>
Date: Mon, 28 Nov 2022 09:20:27 +0100
Subject: [PATCH] refactor: update `makeURLSearchParams` to accept readonly
 non-`Record`s (#8868)

---
 packages/rest/__tests__/utils.test.ts | 27 +++++++++++++++++++++++++++
 packages/rest/src/lib/utils/utils.ts  |  2 +-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/packages/rest/__tests__/utils.test.ts b/packages/rest/__tests__/utils.test.ts
index 90482b9ad..f924f1791 100644
--- a/packages/rest/__tests__/utils.test.ts
+++ b/packages/rest/__tests__/utils.test.ts
@@ -58,4 +58,31 @@ describe('makeURLSearchParams', () => {
 			expect([...params.entries()]).toEqual([['foo', 'bar']]);
 		});
 	});
+
+	describe('types', () => {
+		interface TestInput {
+			foo: string;
+		}
+
+		test("GIVEN object without index signature THEN TypeScript doesn't raise a type error", () => {
+			// Previously, `makeURLSearchParams` used `Record<string, unknown>` as an input, but that meant that it
+			// couldn't accept most interfaces, since they don't have an index signature. This test is to make sure
+			// non-Records can be used without casting.
+
+			const input = { foo: 'bar' } as TestInput;
+			const params = makeURLSearchParams(input);
+
+			expect([...params.entries()]).toEqual([['foo', 'bar']]);
+		});
+
+		test("GIVEN readonly object on a non-readonly generic type THEN TypeScript doesn't raise a type error", () => {
+			// While `Readonly<T>` type was always accepted in `makeURLSearchParams`, this test is to ensure that we can
+			// use the generic type and accept `Readonly<T>` rather than only [possibly] mutable `T`.
+
+			const input = Object.freeze({ foo: 'bar' } as TestInput);
+			const params = makeURLSearchParams<TestInput>(input);
+
+			expect([...params.entries()]).toEqual([['foo', 'bar']]);
+		});
+	});
 });
diff --git a/packages/rest/src/lib/utils/utils.ts b/packages/rest/src/lib/utils/utils.ts
index 6034fdaa5..dcbcf1bc1 100644
--- a/packages/rest/src/lib/utils/utils.ts
+++ b/packages/rest/src/lib/utils/utils.ts
@@ -43,7 +43,7 @@ function serializeSearchParam(value: unknown): string | null {
  * @param options - The options to use
  * @returns A populated URLSearchParams instance
  */
-export function makeURLSearchParams(options?: Record<string, unknown>) {
+export function makeURLSearchParams<T extends object>(options?: Readonly<T>) {
 	const params = new URLSearchParams();
 	if (!options) return params;