Update eslint config to flat (v 9) version. (fix #61)

eslint.config.mjs

@@ -0,0 +1,91 @@
+// @ts-check
+import eslint from "@eslint/js";
+import prettier from "eslint-config-prettier";
+import pluginJest from "eslint-plugin-jest";
+import simpleImportSort from "eslint-plugin-simple-import-sort";
+import globals from "globals";
+import tseslint from "typescript-eslint";
+
+export default tseslint.config(
+  eslint.configs.recommended,
+  tseslint.configs.strictTypeChecked,
+  tseslint.configs.stylisticTypeChecked,
+  prettier,
+
+  {
+    // A config object with just an `ignores` key is the replacement for `.eslintignore`.
+    // Patterns for all files and directories that will be ignored by eslint.
+    ignores: [
+      "**/bin/**",
+      "**/dist/**",
+      "*/**/*.js",
+      "*/**/*.d.ts",
+      "*/**/*.pkl.js",
+      "codegen/snippet-tests/output/**/*",
+    ],
+  },
+  /**
+   * Global configuration settings (for all configuration objects).
+   */
+  {
+    plugins: {
+      "simple-import-sort": simpleImportSort,
+    },
+    languageOptions: {
+      parserOptions: {
+        projectService: {
+          /** Files that will be linted that are not included in the defaultProject (tsconfig) file. See [typescript-eslint allowedDefaultProject](https://typescript-eslint.io/packages/parser#allowdefaultproject) */
+          allowDefaultProject: [
+            ".out/*.pkl.ts",
+            "examples/basic-intro/*.ts",
+            "examples/basic-intro/generated/*.pkl.ts",
+            "examples/express-server/*.ts",
+            "examples/express-server/generated/*.pkl.ts",
+          ],
+          defaultProject: "tsconfig.json", // Required when using allowDefaultProject
+        },
+        tsconfigRootDir: import.meta.dirname,
+      },
+      globals: {
+        ...globals.node,
+      },
+    },
+    rules: {
+      "@typescript-eslint/consistent-type-imports": "error",
+      "simple-import-sort/imports": "error",
+      camelcase: ["error", { properties: "always" }],
+      eqeqeq: ["error", "always"],
+      "prefer-const": "error",
+      "no-throw-literal": "error",
+      "@typescript-eslint/switch-exhaustiveness-check": "error",
+      // Specifically allow "_" as a placeholder argument name
+      "@typescript-eslint/no-unused-vars": ["error", { argsIgnorePattern: "^_$" }],
+    },
+  },
+
+  /**
+   * Config specific only to configuration files in project root
+   */
+  {
+    name: "Configuration files in project root",
+    files: ["./*.js", "./.*.js", "./*.mjs"],
+    extends: [tseslint.configs.disableTypeChecked],
+    rules: {
+      "@typescript-eslint/no-var-requires": "off",
+    },
+  },
+  /**
+   * Config specific to test files only.
+   */
+  {
+    name: "Test files",
+    files: ["**/*.test.ts"],
+    plugins: { jest: pluginJest },
+    languageOptions: {
+      globals: {
+        // recognize 'describe', 'it', 'expect', etc. from jest
+        ...globals.jest,
+      },
+    },
+  },
+);