fix: resolve TypeScript errors in test mocks

Author: Reza Karim Zadeh

test/unit/eslint-plugin-next/utils/url.test.ts

@@ -0,0 +1,142 @@
+import path from 'path'
+
+describe('getPageExtensions()', () => {
+  const originalCwd = process.cwd
+
+  afterEach(() => {
+    jest.resetModules()
+    jest.restoreAllMocks()
+  })
+
+  afterAll(() => {
+    process.cwd = originalCwd
+  })
+
+  it('returns default extensions when next.config.js is not found', () => {
+    jest.isolateModules(() => {
+      const getPageExtensions =
+        require('../../../../packages/eslint-plugin-next/src/utils/url').getPageExtensions
+
+      expect(getPageExtensions()).toEqual(['tsx', 'ts', 'jsx', 'js'])
+    })
+  })
+
+  it('returns custom extensions from next.config.js', () => {
+    jest.isolateModules(() => {
+      const fs = require('fs')
+      jest.spyOn(fs, 'existsSync').mockReturnValue(true as any)
+
+      jest.doMock(
+        path.resolve(process.cwd(), 'next.config.js'),
+        () => ({ pageExtensions: ['md', 'mdx'] }),
+        { virtual: true }
+      )
+
+      const getPageExtensions =
+        require('../../../../packages/eslint-plugin-next/src/utils/url').getPageExtensions
+
+      expect(getPageExtensions()).toEqual(['md', 'mdx'])
+    })
+  })
+
+  it('falls back to default when pageExtensions is not an array', () => {
+    jest.doMock(
+      path.resolve(process.cwd(), 'next.config.js'),
+      () => ({ pageExtensions: 'invalid' }),
+      { virtual: true }
+    )
+
+    jest.isolateModules(() => {
+      const getPageExtensions =
+        require('../../../../packages/eslint-plugin-next/src/utils/url').getPageExtensions
+
+      expect(getPageExtensions()).toEqual(['tsx', 'ts', 'jsx', 'js'])
+    })
+  })
+
+  it('removes leading dots from extensions', () => {
+    jest.isolateModules(() => {
+      const fs = require('fs')
+      jest.spyOn(fs, 'existsSync').mockReturnValue(true as any)
+
+      jest.doMock(
+        path.resolve(process.cwd(), 'next.config.js'),
+        () => ({ pageExtensions: ['.tsx', '.ts'] }),
+        { virtual: true }
+      )
+
+      const getPageExtensions =
+        require('../../../../packages/eslint-plugin-next/src/utils/url').getPageExtensions
+
+      expect(getPageExtensions()).toEqual(['tsx', 'ts'])
+    })
+  })
+
+  it('returns default when pageExtensions is empty array', () => {
+    jest.doMock(
+      path.resolve(process.cwd(), 'next.config.js'),
+      () => ({ pageExtensions: [] }),
+      { virtual: true }
+    )
+
+    jest.isolateModules(() => {
+      const getPageExtensions =
+        require('../../../../packages/eslint-plugin-next/src/utils/url').getPageExtensions
+
+      expect(getPageExtensions()).toEqual(['tsx', 'ts', 'jsx', 'js'])
+    })
+  })
+
+  it('supports next.config.mjs with ES module export', () => {
+    jest.isolateModules(() => {
+      const fs = require('fs')
+      jest.spyOn(fs, 'existsSync').mockImplementation(((filepath: unknown) => {
+        if (String(filepath).endsWith('next.config.mjs')) return true
+        return false
+      }) as any)
+
+      jest.doMock(
+        path.resolve(process.cwd(), 'next.config.mjs'),
+        () => ({ default: { pageExtensions: ['page.tsx', 'page.ts'] } }),
+        { virtual: true }
+      )
+
+      const getPageExtensions =
+        require('../../../../packages/eslint-plugin-next/src/utils/url').getPageExtensions
+
+      expect(getPageExtensions()).toEqual(['page.tsx', 'page.ts'])
+    })
+  })
+
+  it('handles custom extensions like .page.tsx and .mdx', () => {
+    jest.isolateModules(() => {
+      const fs = require('fs')
+      jest.spyOn(fs, 'existsSync').mockReturnValue(true as any)
+
+      jest.doMock(
+        path.resolve(process.cwd(), 'next.config.js'),
+        () => ({ pageExtensions: ['page.tsx', 'page.ts', 'mdx'] }),
+        { virtual: true }
+      )
+
+      const getPageExtensions =
+        require('../../../../packages/eslint-plugin-next/src/utils/url').getPageExtensions
+
+      expect(getPageExtensions()).toEqual(['page.tsx', 'page.ts', 'mdx'])
+    })
+  })
+
+  it('memoizes the result on subsequent calls', () => {
+    jest.isolateModules(() => {
+      const {
+        getPageExtensions,
+      } = require('../../../../packages/eslint-plugin-next/src/utils/url')
+
+      const firstCall = getPageExtensions()
+      const secondCall = getPageExtensions()
+
+      expect(firstCall).toBe(secondCall) // Same reference
+      expect(firstCall).toEqual(['tsx', 'ts', 'jsx', 'js'])
+    })
+  })
+})