chore: add eslint and tighter typescript rules, and adapt codebase to them

collab-server/src/server.ts

@@ -13,7 +13,7 @@ if (process.argv.length !== 3) {
   process.exit(1)
 }
 
-const projectDir = process.argv[2]
+const projectDir = process.argv[2]!
 const socketPath = path.join(process.cwd(), 'collab.sock')
 const dbPath = path.join(process.cwd(), 'collab.db')
 
@@ -63,8 +63,9 @@ const server = new Server({
         doc.getText(YTEXT_KEY).insert(0, content)
         return Y.encodeStateAsUpdate(doc)
       },
-      async store({ documentName, state }) {
+      store({ documentName, state }) {
         upsertDocument(documentName, state)
+        return Promise.resolve()
       },
     }),
   ],
@@ -84,7 +85,8 @@ server.httpServer.listen(socketPath, () => {
   Object.defineProperty(server, 'httpURL', {
     get: () => `http+unix:${socketPath}`,
   })
-  server['showStartScreen']()
+  // Deliberate abstraction violation to call showStartScreen()
+  ;(server as unknown as { showStartScreen(): void }).showStartScreen()
 
   // No need to call `onListen` hooks here since we don't register any.
 })
@@ -96,7 +98,7 @@ console.log('Hocuspocus shutting down..')
 await Promise.all(
   [...server.hocuspocus.documents.values()].map(async doc => {
     try {
-      await fs.writeFile(checkedToDiskPath(doc.name), doc.getText(YTEXT_KEY).toString())
+      await fs.writeFile(checkedToDiskPath(doc.name), doc.getText(YTEXT_KEY).toJSON())
       console.log(`Saved '${doc.name}' to disk`)
     } catch (e) {
       console.error(`Failed to save '${doc.name}' to disk:`, e)

eslint.config.mjs

@@ -1,10 +1,12 @@
+import eslint from '@eslint/js'
 import { defineConfig, globalIgnores } from 'eslint/config'
 import nextVitals from 'eslint-config-next/core-web-vitals'
 import nextTs from 'eslint-config-next/typescript'
 import prettier from 'eslint-config-prettier/flat'
 import noRelativeImportPaths from 'eslint-plugin-no-relative-import-paths'
 import simpleImportSort from 'eslint-plugin-simple-import-sort'
 import unusedImports from 'eslint-plugin-unused-imports'
+import tseslint from 'typescript-eslint'
 
 const eslintConfig = defineConfig([
   ...nextVitals,
@@ -15,6 +17,7 @@ const eslintConfig = defineConfig([
     // vscode-workbench:
     '*/dist/',
     '*/.vscode-test/',
+    'vscode-workbench/src/vscode.proposed.*.d.ts',
     // Default ignores of eslint-config-next:
     '.next/',
     'out/',
@@ -23,28 +26,65 @@ const eslintConfig = defineConfig([
     'branch-*/',
   ]),
   {
+    extends: [eslint.configs.recommended],
     plugins: {
       'simple-import-sort': simpleImportSort,
       'unused-imports': unusedImports,
     },
     rules: {
-      '@typescript-eslint/no-unused-vars': 'off',
+      'no-unused-vars': ['error', { args: 'none', caughtErrors: 'none' }],
       'simple-import-sort/imports': 'warn',
-      'unused-imports/no-unused-imports': 'warn',
       'unused-imports/no-unused-vars': ['warn', { argsIgnorePattern: '^_', varsIgnorePattern: '^_' }],
     },
   },
+  {
+    // Typescript rules
+    files: ['**/*.{mts,ts,tsx}'],
+    extends: tseslint.configs.recommendedTypeChecked,
+    languageOptions: { parserOptions: { projectService: true } },
+    rules: {
+      '@typescript-eslint/no-unused-vars': ['error', { args: 'none', varsIgnorePattern: '^_', caughtErrors: 'none' }],
+      '@typescript-eslint/no-misused-promises': [
+        'error',
+        {
+          // these exceptions reduce unnecessary friction with React stuff
+          checksVoidReturn: {
+            arguments: false,
+            attributes: false,
+          },
+        },
+      ],
+      '@typescript-eslint/restrict-template-expressions': 'off', // always allow `${x}` regardless of x's type
+      '@typescript-eslint/no-confusing-void-expression': ['error', { ignoreArrowShorthand: true }], // allow (x) => console.log(x), ban const x = console.log(x)
+      '@typescript-eslint/no-unnecessary-condition': 'error',
+      '@typescript-eslint/no-unnecessary-type-assertion': 'error',
+      '@typescript-eslint/no-unsafe-member-access': ['error', { allowOptionalChaining: true }], // optional chaining helps with tests
+      '@typescript-eslint/use-unknown-in-catch-callback-variable': 'error', // complements how strict works in typescript for chained promises
+    },
+  },
   {
     // Rules that only make sense in the app
     files: ['src/**/*.{mts,ts,tsx}'],
     plugins: { 'no-relative-import-paths': noRelativeImportPaths },
     rules: {
+      '@typescript-eslint/require-await': 'off', // `'use server'` modules must only export async
       'no-relative-import-paths/no-relative-import-paths': [
         'warn',
         { allowSameFolder: true, rootDir: 'src', prefix: '@' },
       ],
     },
   },
+  {
+    // Test files may need to make use of the `any` type in a way we want to
+    // prevent in normal code.
+    files: ['**/*.{spec,test}.{ts,tsx}', '**/tests/**'],
+    rules: {
+      '@typescript-eslint/no-unsafe-argument': 'off',
+      '@typescript-eslint/no-unsafe-assignment': 'off',
+      '@typescript-eslint/no-unsafe-member-access': 'off',
+      '@typescript-eslint/unbound-method': 'off',
+    },
+  },
 ])
 
 export default eslintConfig