fix(create-app): support github url has trailing slash (#39665)

## Bug

- [x] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

The PR fixes #39642, by supporting GitHub repo URLs with a trailing slash while without branch and path.

packages/create-next-app/helpers/examples.ts

@@ -25,9 +25,15 @@ export async function getRepoInfo(
   const [, username, name, t, _branch, ...file] = url.pathname.split('/')
   const filePath = examplePath ? examplePath.replace(/^\//, '') : file.join('/')
 
-  // Support repos whose entire purpose is to be a NextJS example, e.g.
-  // https://github.com/:username/:my-cool-nextjs-example-repo-name.
-  if (t === undefined) {
+  if (
+    // Support repos whose entire purpose is to be a NextJS example, e.g.
+    // https://github.com/:username/:my-cool-nextjs-example-repo-name.
+    t === undefined ||
+    // Support GitHub URL that ends with a trailing slash, e.g.
+    // https://github.com/:username/:my-cool-nextjs-example-repo-name/
+    // In this case "t" will be an empty string while the next part "_branch" will be undefined
+    (t === '' && _branch === undefined)
+  ) {
     const infoResponse = await got(
       `https://api.github.com/repos/${username}/${name}`
     ).catch((e) => e)

test/integration/create-next-app/index.test.ts

@@ -186,6 +186,36 @@ describe('create next app', () => {
     })
   })
 
+  it('should allow example with GitHub URL with trailing slash', async () => {
+    await usingTempDir(async (cwd) => {
+      const projectName = 'github-app'
+      const res = await run(
+        [
+          projectName,
+          '--example',
+          'https://github.com/vercel/nextjs-portfolio-starter/',
+        ],
+        {
+          cwd,
+        }
+      )
+
+      expect(res.exitCode).toBe(0)
+      expect(
+        fs.existsSync(path.join(cwd, projectName, 'package.json'))
+      ).toBeTruthy()
+      expect(
+        fs.existsSync(path.join(cwd, projectName, 'pages/index.mdx'))
+      ).toBeTruthy()
+      expect(
+        fs.existsSync(path.join(cwd, projectName, '.gitignore'))
+      ).toBeTruthy()
+      expect(
+        fs.existsSync(path.join(cwd, projectName, 'node_modules/next'))
+      ).toBe(true)
+    })
+  })
+
   it('should allow example with GitHub URL and example-path', async () => {
     await usingTempDir(async (cwd) => {
       const projectName = 'github-example-path'