chore upgrade ESLint to latest 8.x and migrate to Flat Config

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "eslint.useFlatConfig": true
+}

packages/client/e2e/fixtures.ts

@@ -89,13 +89,16 @@ export const test = base.extend<IPlaywrightFixtures>({
   fxPagesRec: async ({ context }, use, workerInfo) => {
     const contextPages = context.pages()
     if (isOpenFin(workerInfo)) {
-      const pages = fxOpenfinUrlPaths.reduce((rec, urlPath) => {
-        const page = contextPages.find(
-          (p) => p.url() === `${process.env.E2E_RTC_WEB_ROOT_URL}/${urlPath}`,
-        )
-        if (!page) throw Error(`Openfin page at ${urlPath} was not found`)
-        return { ...rec, [urlPathToFxPage(urlPath)]: page }
-      }, {} as Record<FXPage, Page>)
+      const pages = fxOpenfinUrlPaths.reduce(
+        (rec, urlPath) => {
+          const page = contextPages.find(
+            (p) => p.url() === `${process.env.E2E_RTC_WEB_ROOT_URL}/${urlPath}`,
+          )
+          if (!page) throw Error(`Openfin page at ${urlPath} was not found`)
+          return { ...rec, [urlPathToFxPage(urlPath)]: page }
+        },
+        {} as Record<FXPage, Page>,
+      )
       use(pages)
     } else {
       const mainWindow =
@@ -111,13 +114,16 @@ export const test = base.extend<IPlaywrightFixtures>({
   creditPagesRec: async ({ context }, use, workerInfo) => {
     const contextPages = context.pages()
     if (isOpenFin(workerInfo)) {
-      const pages = creditOpenfinUrlPaths.reduce((rec, urlPath) => {
-        const page = contextPages.find(
-          (p) => p.url() === `${process.env.E2E_RTC_WEB_ROOT_URL}/${urlPath}`,
-        )
-        if (!page) throw Error(`Openfin page at ${urlPath} was not found`)
-        return { ...rec, [urlPathToCreditPage(urlPath)]: page }
-      }, {} as Record<CreditPage, Page>)
+      const pages = creditOpenfinUrlPaths.reduce(
+        (rec, urlPath) => {
+          const page = contextPages.find(
+            (p) => p.url() === `${process.env.E2E_RTC_WEB_ROOT_URL}/${urlPath}`,
+          )
+          if (!page) throw Error(`Openfin page at ${urlPath} was not found`)
+          return { ...rec, [urlPathToCreditPage(urlPath)]: page }
+        },
+        {} as Record<CreditPage, Page>,
+      )
       use(pages)
     } else {
       const mainWindow =

packages/client/eslint.config.js

@@ -0,0 +1,93 @@
+import js from "@eslint/js"
+import react from "eslint-plugin-react"
+import hooks from "eslint-plugin-react-hooks"
+import simpleImportSort from "eslint-plugin-simple-import-sort"
+import globals from "globals"
+import tseslint from "typescript-eslint"
+
+// Tried to introduce typechecking to this file, but requires
+// * .js to be added to tsconfig.json
+// * // @ts-check at the top of this file
+// * this /** @type {import('@typescript-eslint/utils').TSESLint.FlatConfig.ConfigFile} */
+// ... and even then eslint-plugin-react has no (useful) types .. sigh
+//
+export default [
+  js.configs.recommended,
+  ...tseslint.configs.recommended,
+  {
+    plugins: {
+      // https://github.com/lydell/eslint-plugin-simple-import-sort
+      "simple-import-sort": simpleImportSort,
+      // https://typescript-eslint.io/getting-started/
+      "@typescript-eslint": tseslint.plugin,
+      // https://github.com/jsx-eslint/eslint-plugin-react
+      react,
+      // https://github.com/facebook/react/tree/main/packages/eslint-plugin-react-hooks
+      // compat with ESLint v9, see https://github.com/facebook/react/issues/28313
+      "react-hooks": hooks,
+    },
+    languageOptions: {
+      parser: tseslint.parser,
+      parserOptions: {
+        ecmaFeatures: {
+          jsx: true,
+        },
+      },
+      ecmaVersion: "latest",
+      sourceType: "module",
+      globals: {
+        ...globals.browser,
+      },
+    },
+    settings: {
+      react: {
+        version: "detect",
+      },
+    },
+    // note: many tseslint rules require the base eslint rule to be disabled
+    rules: {
+      // https://typescript-eslint.io/rules/no-unused-vars/
+      // with options to ignore _-prefixed args
+      "no-unused-vars": "off",
+      "@typescript-eslint/no-unused-vars": [
+        "error",
+        {
+          argsIgnorePattern: "^_",
+          caughtErrorsIgnorePattern: "^_",
+        },
+      ],
+      // https://eslint.org/docs/latest/rules/no-loss-of-precision
+      "no-loss-of-precision": "off",
+      "@typescript-eslint/no-loss-of-precision": "off",
+      // https://typescript-eslint.io/rules/no-unused-expressions/
+      // with options to allow terse conditionals in functions (debatable)
+      "no-unused-expressions": "off",
+      "@typescript-eslint/no-unused-expressions": [
+        "error",
+        {
+          allowShortCircuit: true,
+          allowTernary: true,
+          enforceForJSX: true,
+        },
+      ],
+
+      // with new flat config, we need to "switch on" the import errors
+      // ref https://github.com/lydell/eslint-plugin-simple-import-sort#usage
+      "simple-import-sort/imports": "error",
+      "simple-import-sort/exports": "error",
+
+      // as hooks plugin does not play well with Flat Config right now, do this
+      ...hooks.configs.recommended.rules,
+    },
+  },
+  {
+    // special blanket rules for mocks/tests
+    files: ["**/*.{service-mock,mock,test,spec}.{ts,tsx}", "**/__mocks__/*"],
+    rules: {
+      "@typescript-eslint/no-explicit-any": "off",
+      "@typescript-eslint/no-non-null-assertion": "off",
+      "@typescript-eslint/no-require-imports": "off",
+      "@typescript-eslint/no-var-requires": "off",
+    },
+  },
+]