test(create-next-app): assert for typescript template dependencies (v…

…ercel#25214)

This PR aims at updating the `create-next-app` test suite to include an assertion for the dependencies specific to the typescript template.
https://github.com/vercel/next.js/blob/218c6114c9f5ed5c6d65840037673c841f44536b/packages/create-next-app/create-app.ts#L214-L216

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

@@ -97,9 +97,9 @@ describe('create next app', () => {
       const res = await run([projectName, '--typescript'], { cwd })
       expect(res.exitCode).toBe(0)
 
-      expect(
-        fs.existsSync(path.join(cwd, projectName, 'package.json'))
-      ).toBeTruthy()
+      const pkgJSONPath = path.join(cwd, projectName, 'package.json')
+
+      expect(fs.existsSync(pkgJSONPath)).toBeTruthy()
       expect(
         fs.existsSync(path.join(cwd, projectName, 'pages/index.tsx'))
       ).toBeTruthy()
@@ -119,6 +119,18 @@ describe('create next app', () => {
       expect(
         fs.existsSync(path.join(cwd, projectName, '.gitignore'))
       ).toBeTruthy()
+
+      // Assert for dependencies specific to the typescript template
+      const pkgJSON = require(pkgJSONPath)
+      expect(Object.keys(pkgJSON.dependencies)).toEqual([
+        'next',
+        'react',
+        'react-dom',
+      ])
+      expect(Object.keys(pkgJSON.devDependencies)).toEqual([
+        '@types/react',
+        'typescript',
+      ])
     })
   })