fix(PageIterator): can't get the last element with collect method

pagination.test.ts

@@ -0,0 +1,64 @@
+import { PageIterator } from "./pagination.ts";
+import { assertEquals } from "std/assert/mod.ts";
+
+type MockArtist = {
+	id: number;
+	type: "artist";
+	name: string;
+};
+const totalMockItems = 50;
+const mockArtists: MockArtist[] = Array(totalMockItems).fill(0).map((
+	_,
+	i,
+) => ({
+	id: i,
+	type: "artist",
+	name: "Radiohead",
+}));
+
+Deno.test("PageIterator: asyncIterator", async () => {
+	const pageIterator = new PageIterator((opts) => {
+		const limit = opts.limit || 20;
+		const offset = opts.offset || 0;
+
+		return Promise.resolve({
+			href: "#",
+			items: mockArtists.slice(offset, offset + limit),
+			offset,
+			limit,
+			next: offset + limit < totalMockItems ? "http://example.com" : null,
+			previous: offset > 0 ? "http://example.com" : null,
+			total: totalMockItems,
+		});
+	});
+
+	const iter = pageIterator.asyncIterator();
+
+	for (let i = 0; i < totalMockItems; i++) {
+		assertEquals(await iter.next(), { done: false, value: mockArtists[i] });
+	}
+	assertEquals(await iter.next(), {
+		done: true,
+		value: null,
+	});
+});
+
+Deno.test("PageIterator: collect", async () => {
+	const pageIterator = new PageIterator((opts) => {
+		const limit = opts.limit || 20;
+		const offset = opts.offset || 0;
+
+		return Promise.resolve({
+			href: "#",
+			items: mockArtists.slice(offset, offset + limit),
+			offset,
+			limit,
+			next: offset + limit < totalMockItems ? "http://example.com" : null,
+			previous: offset > 0 ? "http://example.com" : null,
+			total: totalMockItems,
+		});
+	});
+
+	const items = await pageIterator.collect();
+	assertEquals(items, mockArtists);
+});

pagination.ts

@@ -82,11 +82,11 @@ export class PageIterator<TItem> {
 		this.defaults = { ...DEFAULTS, ...defaults };
 	}
 
-	asyncIterator(): AsyncGenerator<TItem, TItem, unknown> {
+	asyncIterator(): AsyncGenerator<TItem, null, unknown> {
 		return this[Symbol.asyncIterator]();
 	}
 
-	async *[Symbol.asyncIterator](): AsyncGenerator<TItem, TItem> {
+	async *[Symbol.asyncIterator](): AsyncGenerator<TItem, null, unknown> {
 		let { direction, limit, offset } = this.defaults;
 
 		while (true) {
@@ -96,10 +96,8 @@ export class PageIterator<TItem> {
 				(direction === "next" && !chunk.next) ||
 				(direction === "prev" && !chunk.previous)
 			) {
-				const last = chunk.items.pop()!;
 				for (const item of chunk.items) yield item;
-
-				return last;
+				return null;
 			}
 
 			for (const item of chunk.items) yield item;