chore: lint against runtime imports of devDependencies (#852)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: TwitchBronBron

.eslintrc.js

@@ -13,13 +13,28 @@ module.exports = {
     plugins: [
         '@typescript-eslint',
         'no-only-tests',
-        'github'
+        'github',
+        'import'
     ],
     extends: [
         'eslint:all',
         'plugin:@typescript-eslint/all'
     ],
     rules: {
+        //fail if a runtime source file imports a package that isn't listed in `dependencies`.
+        //this catches the case where a package used at runtime is only present in `devDependencies`,
+        //which gets stripped when the extension is packaged into a .vsix (see the dayjs regression).
+        //devDependencies are only permitted in the test/tooling globs listed below.
+        'import/no-extraneous-dependencies': ['error', {
+            devDependencies: [
+                'scripts/**',
+                'benchmarks/**',
+                '.eslintrc.js',
+                '**/*.config.*'
+            ],
+            optionalDependencies: false,
+            peerDependencies: true
+        }],
         '@typescript-eslint/parameter-properties': 'off',
         '@typescript-eslint/array-type': 'off',
         '@typescript-eslint/consistent-type-assertions': 'off',
@@ -202,6 +217,8 @@ module.exports = {
     }, {
         files: ['*.spec.ts'],
         rules: {
+            //spec files only run with devDependencies installed, so extraneous-dependency checks don't apply
+            'import/no-extraneous-dependencies': 'off',
             '@typescript-eslint/no-extraneous-class': 'off',
             '@typescript-eslint/no-unsafe-assignment': 'off',
             '@typescript-eslint/no-unsafe-call': 'off',

package-lock.json

@@ -70,6 +70,7 @@
         "iconv-lite": "0.4.24",
         "jszip": "^3.10.1",
         "just-throttle": "^4.0.1",
+        "lodash": "^4.17.21",
         "md5": "^2.3.0",
         "minimatch": "^3.1.2",
         "node-cache": "^4.2.0",
@@ -122,8 +123,8 @@
         "deferred": "^0.7.11",
         "eslint": "^8.10.0",
         "eslint-plugin-github": "^4.3.5",
+        "eslint-plugin-import": "^2.26.0",
         "eslint-plugin-no-only-tests": "^2.6.0",
-        "lodash": "^4.17.21",
         "mocha": "^10.8.2",
         "node-notifier": "^10.0.1",
         "nyc": "^15.0.0",

package.json

@@ -189,7 +189,7 @@ export abstract class BaseWebviewViewProvider implements vscode.WebviewViewProvi
         try {
             let watcher;
             try {
-                // eslint-disable-next-line @typescript-eslint/no-require-imports
+                // eslint-disable-next-line @typescript-eslint/no-require-imports, import/no-extraneous-dependencies
                 watcher = require('@parcel/watcher');
             } catch (e) {
                 // Doing nothing if watcher does not exist