Address lint issues

addon/.eslintrc.cjs

@@ -0,0 +1,49 @@
+'use strict';
+
+module.exports = {
+  root: true,
+  parser: '@babel/eslint-parser',
+  parserOptions: {
+    ecmaVersion: 'latest',
+    sourceType: 'module',
+    ecmaFeatures: {
+      legacyDecorators: true,
+    },
+    babelOptions: {
+      root: __dirname,
+    },
+  },
+  plugins: ['ember'],
+  extends: [
+    'eslint:recommended',
+    'plugin:ember/recommended',
+    'plugin:prettier/recommended',
+  ],
+  env: {
+    browser: true,
+  },
+  rules: {
+    'ember/no-test-support-import': 'off',
+    'ember/no-classic-classes': 'off',
+  },
+  overrides: [
+    // node files
+    {
+      files: [
+        './.eslintrc.js',
+        './.prettierrc.js',
+        './.template-lintrc.js',
+        './addon-main.js',
+      ],
+      parserOptions: {
+        sourceType: 'script',
+      },
+      env: {
+        browser: false,
+        node: true,
+      },
+      plugins: ['node'],
+      extends: ['plugin:node/recommended'],
+    },
+  ],
+};

addon/package.json

@@ -31,9 +31,7 @@
     "build": "rollup --config",
     "lint": "concurrently 'npm:lint:*(!fix)' --names 'lint:'",
     "lint:fix": "concurrently 'npm:lint:*:fix' --names 'fix:'",
-    "lint:hbs": "ember-template-lint . --no-error-on-unmatched-pattern",
     "lint:js": "eslint . --cache",
-    "lint:hbs:fix": "ember-template-lint . --fix --no-error-on-unmatched-pattern",
     "lint:js:fix": "eslint . --fix",
     "start": "rollup --config --watch",
     "test:types": "tsc --noEmit --project types",

addon/src/adapter.js

@@ -1,4 +1,4 @@
-import Ember from 'ember';
+import TestAdapter from '@ember/test/adapter';
 import * as QUnit from 'qunit';
 import hasEmberVersion from '@ember/test-helpers/has-ember-version';
 
@@ -27,7 +27,7 @@ function unhandledRejectionAssertion(current, error) {
 
 export function nonTestDoneCallback() {}
 
-let Adapter = Ember.Test.Adapter.extend({
+let Adapter = TestAdapter.extend({
   init() {
     this.doneCallbacks = [];
     this.qunit = this.qunit || QUnit;

addon/src/index.js

@@ -124,10 +124,12 @@ export function setupTestAdapter() {
  */
 export function setupEmberTesting() {
   QUnit.testStart(() => {
+    // eslint-disable-next-line ember/no-ember-testing-in-module-scope
     Ember.testing = true;
   });
 
   QUnit.testDone(() => {
+    // eslint-disable-next-line ember/no-ember-testing-in-module-scope
     Ember.testing = false;
   });
 }