[suppressions] enable typescript-eslint (#38876)

Author: mikeharder

.github/workflows/suppressions-test.yaml

@@ -25,3 +25,4 @@ jobs:
     uses: ./.github/workflows/_reusable-eng-tools-test.yaml
     with:
       package: suppressions
+      lint: true

eng/tools/suppressions/eslint.config.js

@@ -0,0 +1,30 @@
+// Keep in sync with .github/shared/eslint.config.js
+
+import eslint from "@eslint/js";
+import { defineConfig } from "eslint/config";
+import globals from "globals";
+import tseslint from "typescript-eslint";
+
+/** @type {import('eslint').Linter.Config[]} */
+export default defineConfig(
+  eslint.configs.recommended,
+  tseslint.configs.recommendedTypeChecked,
+  {
+    languageOptions: {
+      // we only run in node, not browser
+      globals: globals.node,
+      // required to use tseslint.configs.recommendedTypeChecked
+      parserOptions: {
+        projectService: {
+          allowDefaultProject: ["*.js", "cmd/*.js"],
+        },
+        // ensures the tsconfig path resolves relative to this file
+        // default is process.cwd() when running eslint, which may be incorrect
+        tsconfigRootDir: import.meta.dirname,
+      },
+    },
+  },
+  {
+    ignores: ["coverage/**", "dist/**"],
+  },
+);

eng/tools/suppressions/package.json

@@ -8,9 +8,11 @@
   },
   "scripts": {
     "build": "tsc --build",
+    "check": "npm run build && npm run lint && npm run format:check && npm run test:ci",
     "format": "prettier . --ignore-path ../.prettierignore --write",
     "format:check": "prettier . --ignore-path ../.prettierignore --check",
     "format:check:ci": "prettier . --ignore-path ../.prettierignore --check --log-level debug",
+    "lint": "cross-env DEBUG=eslint:eslint eslint",
     "test": "vitest",
     "test:ci": "vitest run --coverage --reporter=verbose"
   },
@@ -23,11 +25,14 @@
     "zod": "^4.1.11"
   },
   "devDependencies": {
+    "@eslint/js": "^9.22.0",
     "@types/node": "^20.0.0",
     "@vitest/coverage-v8": "^3.1.2",
+    "eslint": "^9.22.0",
     "prettier": "~3.6.2",
     "prettier-plugin-organize-imports": "^4.2.0",
     "typescript": "~5.9.2",
+    "typescript-eslint": "^8.45.0",
     "vitest": "^3.2.4"
   }
 }

eng/tools/suppressions/src/suppressions.ts

@@ -36,7 +36,7 @@ const suppressionSchema = z.array(
       path: ["path", "paths"],
     })
     .transform((s) => {
-      let paths: string[] = Array.from(s.paths || []);
+      const paths: string[] = Array.from(s.paths || []);
       if (s.path) {
         // if "path" is defined, it is inserted at the start of "paths".
         paths.unshift(s.path);
@@ -78,17 +78,17 @@ const suppressionSchema = z.array(
 export async function getSuppressions(
   tool: string,
   path: string,
-  context: Record<string, any> = {},
+  context: Record<string, unknown> = {},
 ): Promise<Suppression[]> {
   path = resolve(path);
 
   // If path doesn't exist, throw instead of returning "[]" to prevent confusion
   await access(path, constants.R_OK);
 
-  let suppressionsFiles: string[] = await findSuppressionsFiles(path);
+  const suppressionsFiles: string[] = await findSuppressionsFiles(path);
   let suppressions: Suppression[] = [];
 
-  for (let suppressionsFile of suppressionsFiles) {
+  for (const suppressionsFile of suppressionsFiles) {
     suppressions = suppressions.concat(
       getSuppressionsFromYaml(
         tool,
@@ -135,13 +135,13 @@ export function getSuppressionsFromYaml(
   path: string,
   suppressionsFile: string,
   suppressionsYaml: string,
-  context: Record<string, any> = {},
+  context: Record<string, unknown> = {},
 ): Suppression[] {
   path = resolve(path);
   suppressionsFile = resolve(suppressionsFile);
 
   // Treat empty yaml as empty array
-  const parsedYaml: any = yamlParse(suppressionsYaml) ?? [];
+  const parsedYaml: unknown = yamlParse(suppressionsYaml) ?? [];
 
   let suppressions: Suppression[];
   try {

eng/tools/suppressions/test/suppressions.test.ts

@@ -253,7 +253,7 @@ test("yaml array not suppression", () => {
 });
 
 test("suppression with rules", () => {
-  let suppressions: Suppression[] = getSuppressionsFromYaml(
+  const suppressions: Suppression[] = getSuppressionsFromYaml(
     "TestTool",
     "foo",
     "suppressions.yaml",
@@ -320,7 +320,7 @@ test.each([
   reason: process-version
 `;
 
-  let suppressions: Suppression[] = getSuppressionsFromYaml(
+  const suppressions: Suppression[] = getSuppressionsFromYaml(
     "TestTool",
     "test-path",
     "suppressions.yaml",