Lint tests using eslint-vitest-plugin

Also adds commented `all` Vitest ESLintconfig for later testing purpose.

eslint.config.js

@@ -1,9 +1,9 @@
 import tseslint from 'typescript-eslint'
 import js from '@eslint/js'
+import vitest from 'eslint-plugin-vitest'
 
 export default tseslint.config(
   js.configs.recommended,
-
   {
     files: ['**/*.js'],
     languageOptions: {
@@ -64,4 +64,21 @@ export default tseslint.config(
       'template-tag-spacing': [2, 'always'],
     },
   },
+  {
+    files: ['**/*.test.js'],
+    plugins: { vitest },
+    rules: {
+      ...vitest.configs.recommended.rules,
+      // ...vitest.configs.all.rules, // worth testing from time to time…
+      // 'vitest/consistent-test-it': 0,
+      'vitest/no-test-return-statement': 1,
+      // 'vitest/prefer-expect-assertions': 0, // when testing `vitest.configs.all.rules`
+      'vitest/require-to-throw-message': 1,
+    },
+    languageOptions: {
+      globals: {
+        ...vitest.environments.env.globals,
+      },
+    },
+  },
 )

package.json

@@ -54,10 +54,11 @@
     "@vitest/coverage-v8": "^1.4.0",
     "@vitest/ui": "^1.4.0",
     "eslint": "^9.0.0",
+    "eslint-plugin-vitest": "0.4.2-beta.5",
     "size-limit": "^11.1.2",
     "tsd": "^0.31.0",
     "typescript": "^5.4.4",
-    "typescript-eslint": "^7.5.0",
+    "typescript-eslint": "^7.6.0",
     "vitest": "^1.4.0"
   },
   "pnpm": {

tests/index.test.js

@@ -111,10 +111,10 @@ describe('duration', () => {
   const durationInDays = { d: 43 }
 
   test('is a function', () => expect(duration).toBeInstanceOf(Function))
-  test('()', () => expect(() => duration(null)).toThrow())
+  test('(null)', () => expect(() => duration(null)).toThrow(Error))
   test('()', () => expect(duration()).toBe('PT0S'))
   test('empty object {}', () => expect(duration({})).toBe('PT0S'))
-  test('empty object {}', () => expect(duration({}, false)).toBe('PT0S'))
+  test('empty object {} and preserve excess value', () => expect(duration({}, false)).toBe('PT0S'))
 
   test('complete object', () => expect(duration(durationObject)).toBe('P3W5DT10H43M2.61S'))
   test('complete object with too high values', () => expect(duration(durationWithTooHighValues)).toBe('P5W6DT12H55M55.3S'))
@@ -257,7 +257,7 @@ describe('DateTime class', () => {
   test(".to('month')", () => expect(twoWeeksAfterSummer.to('month')).toBe('2021-07'))
   test('weeks is changed when day changes', () => {
     summer.setDate(summer.getDate() + 14)
-    return expect(summer.getWeek()).toBe(29)
+    expect(summer.getWeek()).toBe(29)
   })
 })