INTER-2222: Upgrade to ESLint v10 flat config

__tests__/fpjs-provider.test.tsx

@@ -11,7 +11,7 @@ vi.mock('@fingerprint/agent', { spy: true })
 const mockStart = vi.mocked(agent.start)
 
 describe('FingerprintProvider', () => {
-  it('should configure an instance of the Fp Agent', async () => {
+  it('should configure an instance of the Fp Agent', () => {
     const loadOptions = getDefaultLoadOptions()
     const wrapper = createWrapper({
       cache: {

__tests__/helpers.tsx

@@ -8,13 +8,16 @@ export const getDefaultLoadOptions = () => ({
 
 export const createWrapper =
   (providerProps: Partial<FingerprintProviderOptions> = {}) =>
-  ({ children }: PropsWithChildren<{}>) => (
+  ({ children }: PropsWithChildren<object>) => (
     <FingerprintProvider {...getDefaultLoadOptions()} {...providerProps}>
       {children}
     </FingerprintProvider>
   )
 
-export const wait = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms))
+export const wait = (ms: number) =>
+  new Promise<void>((resolve) => {
+    setTimeout(resolve, ms)
+  })
 
 export const actWait = async (ms: number) => {
   await act(async () => {

__tests__/use-visitor-data.test.tsx

@@ -32,7 +32,7 @@ describe('useVisitorData', () => {
     mockStart.mockReturnValue(mockAgent)
   })
 
-  it('should provide the Fp context', async () => {
+  it('should provide the Fp context', () => {
     const wrapper = createWrapper()
     const {
       result: { current },
@@ -97,7 +97,7 @@ describe('useVisitorData', () => {
     )
   })
 
-  it("shouldn't call getData on mount if 'immediate' option is set to false", async () => {
+  it("shouldn't call getData on mount if 'immediate' option is set to false", () => {
     mockGet.mockImplementation(() => mockGetResult)
 
     const wrapper = createWrapper()
@@ -141,7 +141,13 @@ describe('useVisitorData', () => {
 
       return (
         <>
-          <button onClick={() => setTag((prev) => prev + 1)}>Change options</button>
+          <button
+            onClick={() => {
+              setTag((prev) => prev + 1)
+            }}
+          >
+            Change options
+          </button>
           <pre>{JSON.stringify(data)}</pre>
         </>
       )
@@ -158,7 +164,8 @@ describe('useVisitorData', () => {
     await actWait(1000)
 
     act(() => {
-      userEvent.click(container.querySelector('button')!)
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      void userEvent.click(container.querySelector('button')!)
     })
 
     await actWait(1000)
@@ -278,7 +285,13 @@ describe('useVisitorData', () => {
       getDataValues.push(getData)
       return (
         <>
-          <button onClick={() => setCount((count) => count + 1)}>Increment count</button>
+          <button
+            onClick={() => {
+              setCount((count) => count + 1)
+            }}
+          >
+            Increment count
+          </button>
           <pre>{JSON.stringify(data)}</pre>
         </>
       )
@@ -293,6 +306,7 @@ describe('useVisitorData', () => {
     )
 
     await act(async () => {
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       await userEvent.click(container.querySelector('button')!)
     })
 
@@ -303,6 +317,7 @@ describe('useVisitorData', () => {
       // in between renders if this click were in the previous act block.
       // This ensures that the case is covered where the options
       // object does not semantically change.
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       await userEvent.click(container.querySelector('button')!)
     })
 

__tests__/with-environment.preact.test.tsx

@@ -15,9 +15,9 @@ describe('WithEnvironment', () => {
     })
     it('should detect env as "preact"', async () => {
       const { WithEnvironment } = await import('../src/components/with-environment')
-      const PrintEnv = (props: any) => h('div', null, props?.env?.name)
+      const PrintEnv = (props: { env?: { name: string } }) => h('div', null, props.env?.name)
 
-      // @ts-ignore
+      // @ts-expect-error -- preact's render signature does not match React's @testing-library/react types
       const { container } = preactRender(h(WithEnvironment, null, h(PrintEnv, null)))
 
       expect(container.innerHTML).toContain('preact')

__tests__/with-environment.test.tsx

@@ -8,7 +8,7 @@ import { describe, it, expect, vi } from 'vitest'
 
 describe('WithEnvironment', () => {
   it('enhances provided element with `env` prop', () => {
-    const Mock = vi.fn(() => <div>foo</div>) as FunctionComponent
+    const Mock: FunctionComponent = vi.fn(() => <div>foo</div>)
 
     render(
       <WithEnvironment>
@@ -56,7 +56,8 @@ describe('WithEnvironment', () => {
     )
 
     act(() => {
-      userEvent.click(container.querySelector('#test')!)
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      void userEvent.click(container.querySelector('#test')!)
     })
 
     await actWait(250)

eslint.config.mjs

@@ -0,0 +1,60 @@
+import { includeIgnoreFile } from 'eslint/config'
+import path from 'path'
+import { fileURLToPath } from 'url'
+import cfg from '@fingerprintjs/eslint-config-dx-team/type-checked'
+import tseslint from 'typescript-eslint'
+import nextConfig from 'eslint-config-next/core-web-vitals'
+
+const __dirname = fileURLToPath(new URL('.', import.meta.url))
+
+const config = [
+  includeIgnoreFile(path.resolve(__dirname, '.gitignore')),
+  { ignores: ['examples/'] },
+  ...cfg,
+  ...nextConfig,
+  // eslint-config-next overrides the parser to @babel/eslint-parser for all files, then
+  // restores @typescript-eslint/parser only for .ts/.tsx. Re-apply it here for .js files
+  // so that the ESLint v10-compatible scope manager is used everywhere.
+  {
+    files: ['**/*.{js,mjs,cjs,jsx}'],
+    languageOptions: { parser: tseslint.parser },
+  },
+  // Point the type-aware rules at a lint-only tsconfig that covers the tests and
+  // root config files, not just `src` (the build tsconfig). Must come after
+  // nextConfig so its parser swap doesn't strip the typed parser off .tsx files.
+  {
+    files: ['**/*.{ts,tsx,mts,cts}'],
+    languageOptions: {
+      parserOptions: {
+        project: './tsconfig.eslint.json',
+        tsconfigRootDir: __dirname,
+      },
+    },
+  },
+  // Pure-JS config/scripts can't join a TS program; disable the type-aware rules there.
+  {
+    files: ['**/*.{js,mjs,cjs,jsx}'],
+    ...tseslint.configs.disableTypeChecked,
+  },
+  // vitest matchers like `expect.any()` return `any`, so asserting on mock call
+  // args trips no-unsafe-assignment. Relax it for tests only.
+  {
+    files: ['__tests__/**/*.{ts,tsx}'],
+    rules: {
+      '@typescript-eslint/no-unsafe-assignment': 'off',
+    },
+  },
+  {
+    settings: {
+      react: { version: '18.2' },
+    },
+    rules: {
+      'react/display-name': 'off',
+      'react/self-closing-comp': ['error', { component: true, html: true }],
+      'react/react-in-jsx-scope': 'off',
+      '@next/next/no-html-link-for-pages': 'off',
+    },
+  },
+]
+
+export default config

examples/preact/eslint.config.mjs

@@ -0,0 +1,29 @@
+import { FlatCompat } from '@eslint/eslintrc'
+import js from '@eslint/js'
+import tseslint from 'typescript-eslint'
+import { fileURLToPath } from 'url'
+
+const __dirname = fileURLToPath(new URL('.', import.meta.url))
+
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+  recommendedConfig: js.configs.recommended,
+  allConfig: js.configs.all,
+})
+
+const config = [
+  { ignores: ['build/'] },
+  ...compat.extends('preact'),
+  ...tseslint.configs.recommended,
+  {
+    rules: {
+      semi: ['error', 'never'],
+      'linebreak-style': ['error', 'unix'],
+      'prefer-const': 'error',
+      '@typescript-eslint/no-unused-vars': ['error'],
+      curly: [2, 'all'],
+    },
+  },
+]
+
+export default config

examples/preact/package.json

@@ -7,21 +7,21 @@
     "build": "preact build --no-sw",
     "serve": "sirv build --port 8080 --cors --single",
     "dev": "preact watch --no-sw",
-    "lint": "eslint 'src/**/*.{js,jsx,ts,tsx}'"
+    "lint": "eslint --max-warnings 0"
   },
   "dependencies": {
     "@fingerprint/react": "workspace:*",
     "preact": "10.19.6",
     "preact-render-to-string": "^6.4.0"
   },
   "peerDependencies": {
-    "@typescript-eslint/eslint-plugin": "*",
-    "@typescript-eslint/parser": "*",
     "eslint": "*",
     "eslint-config-preact": "*",
     "typescript": "*"
   },
   "devDependencies": {
+    "@eslint/js": "^9.0.0",
+    "typescript-eslint": "^8.60.0",
     "dotenv": "^16.4.5",
     "preact-cli": "^3.5.1",
     "sirv-cli": "^2.0.2"

examples/preact/preact.config.js

@@ -2,7 +2,6 @@ import dotenv from 'dotenv'
 
 dotenv.config()
 
-// eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 export default (config, env, helpers) => {
   const { plugin } = helpers.getPluginsByName(config, 'DefinePlugin')[0]
   plugin.definitions['process.env.PREACT_APP_FPJS_PUBLIC_API_KEY'] = JSON.stringify(

package.json

@@ -33,7 +33,8 @@
     "prepare": "husky install",
     "watch": "vite build --watch",
     "build": "vite build",
-    "lint": "eslint --ext .js,.ts,.tsx --ignore-path .gitignore --max-warnings 0 .",
+    "start:spa": "pnpm start --prefix=examples/spa",
+    "lint": "eslint --max-warnings 0",
     "lint:fix": "pnpm lint --fix",
     "test": "vitest",
     "test:coverage": "vitest run --coverage",
@@ -70,7 +71,7 @@
     "@commitlint/cli": "^19.2.0",
     "@fingerprintjs/changesets-changelog-format": "^0.2.0",
     "@fingerprintjs/commit-lint-dx-team": "^0.0.2",
-    "@fingerprintjs/eslint-config-dx-team": "^0.1.0",
+    "@fingerprintjs/eslint-config-dx-team": "^3.0.0",
     "@fingerprintjs/prettier-config-dx-team": "^0.2.0",
     "@fingerprintjs/tsconfig-dx-team": "^0.0.2",
     "@testing-library/preact": "^3.2.4",
@@ -80,12 +81,13 @@
     "@types/react": "^18.2.66",
     "@types/react-dom": "^18.2.22",
     "@vitest/coverage-istanbul": "^4.0.18",
-    "eslint": "8.57.0",
-    "eslint-config-next": "14.1.3",
+    "eslint": "^10.4.1",
+    "eslint-config-next": "^16.2.0",
+    "@eslint/eslintrc": "^3.0.0",
+    "typescript-eslint": "^8.60.0",
     "eslint-config-preact": "^1.3.0",
-    "eslint-plugin-prettier": "^5.5.5",
-    "eslint-plugin-react": "7.34.0",
-    "eslint-plugin-react-hooks": "^4.6.0",
+    "eslint-plugin-react": "^7.37.0",
+    "eslint-plugin-react-hooks": "^7.0.0",
     "husky": "^9.0.11",
     "lint-staged": "^15.2.2",
     "preact": "^10.19.6",