Tests for translate utils

tests/pages/Error.test.tsx

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+import { render, screen } from "@testing-library/react";
+import faker from "faker";
+import Error from "next/error";
+
+it("renders a not found message on 404 code", () => {
+    render(<Error statusCode={404} />);
+    expect(screen.getByText(/this page could not be found/i)).toBeVisible();
+});
+
+it("renders the correct status code", () => {
+    const code = faker.random.number({ min: 100, max: 599 });
+    render(<Error statusCode={code} />);
+    expect(screen.getByText(code)).toBeVisible();
+});

tests/setupTests.ts

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+import '@testing-library/jest-dom';
+import jestFetchMock from 'jest-fetch-mock';
+jestFetchMock.enableMocks();

tests/utils/translate.test.ts

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+import faker from "faker";
+import { googleScrape, extractSlug } from "../../utils/translate";
+
+const source = faker.random.locale();
+const target = faker.random.locale();
+const query = faker.random.words();
+
+describe("googleScrape", () => {
+    beforeEach(() => {
+        fetchMock.resetMocks();
+    });
+
+    it("parses html response correctly", async () => {
+        const translation = faker.random.words();
+        const className = "result-container";
+        const html = `
+            <div class=${className}>
+                ${translation}
+            </div>
+        `;
+        fetchMock.mockResponseOnce(async () => ({ body: html }));
+
+        expect(await googleScrape(source, target, query)).toStrictEqual({ translation });
+    });
+
+    it("returns status code on request error", async () => {
+        const status = faker.random.number({ min: 400, max: 499 });
+        fetchMock.mockResponseOnce(async () => ({ status }));
+
+        expect(await googleScrape(source, target, query)).toStrictEqual({ statusCode: status });
+    });
+
+    it("returns correct message on network error", async () => {
+        fetchMock.mockRejectOnce();
+
+        const res = await googleScrape(source, target, query);
+        expect(res?.errorMsg).toMatch(/retrieving/);
+    });
+
+    it("returns correct message on parsing wrong class", async () => {
+        const translation = faker.random.words();
+        const className = "wrong-container";
+        const html = `
+            <div class=${className}>
+                ${translation}
+            </div>
+        `;
+        fetchMock.mockResponseOnce(async () => ({ body: html }));
+
+        const res = await googleScrape(source, target, query);
+        expect(res?.errorMsg).toMatch(/parsing/);
+    });
+});
+
+describe("extractSlug", () => {
+    it("returns 'query' for 1 param", () => {
+        expect(extractSlug([query])).toStrictEqual({ query });
+    });
+
+    it("returns 'target' & 'query' resp. for 2 params", () => {
+        expect(extractSlug([target, query])).toStrictEqual({ target, query });
+    });
+
+    it("returns 'source', 'target' & 'query' resp. for 3 param", () => {
+        expect(extractSlug([source, target, query])).toStrictEqual({ source, target, query });
+    });
+
+    it("returns empty object on 0 or >4 params", () => {
+        expect(extractSlug([])).toStrictEqual({});
+
+        const length = faker.random.number({ min: 4, max: 50 });
+        const array = Array(length).fill("");
+        expect(extractSlug(array)).toStrictEqual({});
+    });
+});