Tests

package.json

@@ -6,6 +6,7 @@
     "@testing-library/jest-dom": "^4.2.4",
     "@testing-library/react": "^9.3.2",
     "@testing-library/user-event": "^7.1.2",
+    "jest-fetch-mock": "^3.0.3",
     "normalize.css": "^8.0.1",
     "react": "^16.13.1",
     "react-dom": "^16.13.1",
@@ -33,5 +34,6 @@
       "last 1 firefox version",
       "last 1 safari version"
     ]
-  }
+  },
+  "devDependencies": {}
 }

src/App.test.js

@@ -1,9 +1,48 @@
 import React from 'react';
-import { render } from '@testing-library/react';
+import { render, screen } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { MemoryRouter } from 'react-router';
+import fetchMock from 'jest-fetch-mock';
 import App from './App';
+import mockResponse from './__mocks__/subreddit-reactjs-response.json';
 
-test('renders learn react link', () => {
-  const { getByText } = render(<App />);
-  const linkElement = getByText(/learn react/i);
-  expect(linkElement).toBeInTheDocument();
+fetchMock.enableMocks();
+
+function setup() {
+  return render(
+    <MemoryRouter>
+      <App />
+    </MemoryRouter>
+  );
+}
+
+describe('Header', () => {
+  test('"How it works" link points to the correct page', () => {
+    setup();
+
+    const link = screen.getByRole('link', { name: /how it works/i });
+    userEvent.click(link);
+
+    expect(
+      screen.getByRole('heading', { name: /how it works/i })
+    ).toBeInTheDocument();
+  });
+});
+
+describe('Subreddit form', () => {
+  test('loads posts and renders them on the page', async () => {
+    fetch.once(JSON.stringify(mockResponse));
+    setup();
+
+    const subredditInput = screen.getByLabelText('r /');
+    userEvent.type(subredditInput, 'reactjs');
+
+    const submitButton = screen.getByRole('button', { name: /search/i });
+    userEvent.click(submitButton);
+
+    expect(screen.getByText(/is loading/i)).toBeInTheDocument();
+
+    expect(await screen.findByText(/Number of top posts: 25/i)).toBeInTheDocument();
+    expect(fetch).toHaveBeenCalledWith('https://www.reddit.com/r/reactjs/top.json');
+  });
 });

yarn.lock

@@ -3272,6 +3272,13 @@ create-hmac@^1.1.0, create-hmac@^1.1.2, create-hmac@^1.1.4:
     safe-buffer "^5.0.1"
     sha.js "^2.4.8"
 
+cross-fetch@^3.0.4:
+  version "3.0.5"
+  resolved "https://registry.yarnpkg.com/cross-fetch/-/cross-fetch-3.0.5.tgz#2739d2981892e7ab488a7ad03b92df2816e03f4c"
+  integrity sha512-FFLcLtraisj5eteosnX1gf01qYDCOc4fDy0+euOt8Kn9YBY2NtXL/pCoYPavw24NIQkQqm5ZOLsGD5Zzj0gyew==
+  dependencies:
+    node-fetch "2.6.0"
+
 cross-spawn@7.0.1:
   version "7.0.1"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-7.0.1.tgz#0ab56286e0f7c24e153d04cc2aa027e43a9a5d14"
@@ -5934,6 +5941,14 @@ jest-environment-node@^24.9.0:
     jest-mock "^24.9.0"
     jest-util "^24.9.0"
 
+jest-fetch-mock@^3.0.3:
+  version "3.0.3"
+  resolved "https://registry.yarnpkg.com/jest-fetch-mock/-/jest-fetch-mock-3.0.3.tgz#31749c456ae27b8919d69824f1c2bd85fe0a1f3b"
+  integrity sha512-Ux1nWprtLrdrH4XwE7O7InRY6psIi3GOsqNESJgMJ+M5cv4A8Lh7SN9d2V2kKRZ8ebAfcd1LNyZguAOb6JiDqw==
+  dependencies:
+    cross-fetch "^3.0.4"
+    promise-polyfill "^8.1.3"
+
 jest-get-type@^24.9.0:
   version "24.9.0"
   resolved "https://registry.yarnpkg.com/jest-get-type/-/jest-get-type-24.9.0.tgz#1684a0c8a50f2e4901b6644ae861f579eed2ef0e"
@@ -7023,6 +7038,11 @@ no-case@^3.0.3:
     lower-case "^2.0.1"
     tslib "^1.10.0"
 
+node-fetch@2.6.0:
+  version "2.6.0"
+  resolved "https://registry.yarnpkg.com/node-fetch/-/node-fetch-2.6.0.tgz#e633456386d4aa55863f676a7ab0daa8fdecb0fd"
+  integrity sha512-8dG4H5ujfvFiqDmVu9fQ5bOHUC15JMjMY/Zumv26oOvvVJjM67KF8koCWIabKQ1GJIa9r2mMZscBq/TbdOcmNA==
+
 node-forge@0.9.0:
   version "0.9.0"
   resolved "https://registry.yarnpkg.com/node-forge/-/node-forge-0.9.0.tgz#d624050edbb44874adca12bb9a52ec63cb782579"
@@ -8472,6 +8492,11 @@ promise-inflight@^1.0.1:
   resolved "https://registry.yarnpkg.com/promise-inflight/-/promise-inflight-1.0.1.tgz#98472870bf228132fcbdd868129bad12c3c029e3"
   integrity sha1-mEcocL8igTL8vdhoEputEsPAKeM=
 
+promise-polyfill@^8.1.3:
+  version "8.1.3"
+  resolved "https://registry.yarnpkg.com/promise-polyfill/-/promise-polyfill-8.1.3.tgz#8c99b3cf53f3a91c68226ffde7bde81d7f904116"
+  integrity sha512-MG5r82wBzh7pSKDRa9y+vllNHz3e3d4CNj1PQE4BQYxLme0gKYYBm9YENq+UkEikyZ0XbiGWxYlVw3Rl9O/U8g==
+
 promise@^8.0.3:
   version "8.1.0"
   resolved "https://registry.yarnpkg.com/promise/-/promise-8.1.0.tgz#697c25c3dfe7435dd79fcd58c38a135888eaf05e"