refactor: migrate testing framework from Jest to Vitest (#87)

* refactor: migrate testing framework from Jest to Vitest

- Updated package.json to replace Jest with Vitest for testing scripts.
- Removed Jest configuration from package.json.
- Added Vitest configuration in a new vitest.config.ts file.
- Updated tsconfig.json to include Vitest types and exclude vitest.config.ts from compilation.
- Adjusted test scripts to support coverage reporting with Vitest.

* fix: add "type": "module" to package.json

* feat: add Vitest configuration and update references in ESLint and TypeScript config

Author: chrisreddington

.github/linters/eslint.config.mjs

@@ -1,4 +1,4 @@
-import jest from 'eslint-plugin-jest'
+import vitest from 'eslint-plugin-vitest'
 import typescriptEslint from '@typescript-eslint/eslint-plugin'
 import globals from 'globals'
 import tsParser from '@typescript-eslint/parser'
@@ -26,24 +26,24 @@ export default [
       '**/lib/**',
       '**/dist/**',
       '**/coverage/**',
-      '**/.github/linters/**'
+      '**/.github/linters/**',
+      'vitest.config.mts'
     ]
   },
   ...compat.extends(
     'eslint:recommended',
-    'plugin:@typescript-eslint/recommended-type-checked',
-    'plugin:jest/recommended'
+    'plugin:@typescript-eslint/recommended-type-checked'
   ),
+  vitest.configs.recommended,
   {
     plugins: {
-      jest,
+      vitest,
       '@typescript-eslint': typescriptEslint
     },
 
     languageOptions: {
       globals: {
         ...globals.node,
-        ...globals.jest,
         Atomics: 'readonly',
         SharedArrayBuffer: 'readonly'
       },

__tests__/dependabot-validator.test.ts

@@ -6,18 +6,19 @@
 import * as core from '@actions/core'
 import * as github from '@actions/github'
 import { DependabotValidator } from '../src/dependabot-validator'
+import { vi, describe, test, expect, beforeEach } from 'vitest'
 
-jest.mock('@actions/core')
+vi.mock('@actions/core')
 
 /**
  * Test suite for the DependabotValidator class
  */
 describe('DependabotValidator', () => {
   // Setup test environment and mocks
-  const mockSetFailed = jest.mocked(core.setFailed)
-  const mockInfo = jest.mocked(core.info)
+  const mockSetFailed = vi.mocked(core.setFailed)
+  const mockInfo = vi.mocked(core.info)
 
-  const mockGetContent = jest.fn()
+  const mockGetContent = vi.fn()
   const mockOctokit = {
     rest: {
       repos: {
@@ -29,7 +30,7 @@ describe('DependabotValidator', () => {
   const validator = new DependabotValidator(mockOctokit)
 
   beforeEach(() => {
-    jest.clearAllMocks()
+    vi.clearAllMocks()
   })
 
   describe('configuration validation', () => {

__tests__/ecosystem-mapping.test.ts

@@ -4,15 +4,16 @@
  */
 
 import { getEcosystemLanguageMapping } from '../src/ecosystem-mapping'
+import { vi, describe, test, expect, beforeEach } from 'vitest'
 
-jest.mock('@actions/core')
+vi.mock('@actions/core')
 
 /**
  * Test suite for the ecosystem mapping functionality
  */
 describe('ecosystem-mapping module', () => {
   beforeEach(() => {
-    jest.clearAllMocks()
+    vi.clearAllMocks()
   })
 
   describe('language mapping', () => {

__tests__/index.test.ts

@@ -1,21 +1,25 @@
 /**
- * Unit tests for the action's entrypoint (index.ts)
- * Verifies that the action's main function is called when the module is imported
+ * Unit tests for the action's entrypoint (src/index.ts)
  */
 
 import * as main from '../src/main'
+import { vi, describe, it, expect } from 'vitest'
 
-// Mock the action's entrypoint
-const runMock = jest.spyOn(main, 'run').mockImplementation()
+/**
+ * Mock implementation of the main run function
+ */
+const mockRun = vi.spyOn(main, 'run').mockImplementation()
 
 /**
- * Test suite for the index module
+ * Test suite for the action's entry point
  */
-describe('index module', () => {
-  test('should call run function when module is imported', () => {
-    // eslint-disable-next-line @typescript-eslint/no-require-imports
-    require('../src/index')
+describe('index', () => {
+  /**
+   * Test case: Verifies that the run function is called when the index is imported
+   */
+  it('calls run when imported', async () => {
+    await import('../src/index')
 
-    expect(runMock).toHaveBeenCalled()
+    expect(mockRun).toHaveBeenCalled()
   })
 })

__tests__/main.test.ts

@@ -7,35 +7,41 @@ import * as core from '@actions/core'
 import * as github from '@actions/github'
 import { Context } from '@actions/github/lib/context'
 import { run } from '../src/main'
-
-jest.mock('@actions/core')
-jest.mock('@actions/github')
+import {
+  vi,
+  describe,
+  test,
+  expect,
+  beforeEach,
+  type MockInstance
+} from 'vitest'
+
+vi.mock('@actions/core')
+vi.mock('@actions/github')
 
 /**
  * Main test suite for the validate-dependabot integration
  * Tests various scenarios including successful execution and error handling
  */
 describe('validate-dependabot integration', () => {
   // Setup mock implementations
-  const mockGetInput = core.getInput as jest.MockedFunction<
-    typeof core.getInput
-  >
-  const mockSetFailed = core.setFailed as jest.MockedFunction<
-    typeof core.setFailed
-  >
+  let mockGetInput: MockInstance<typeof core.getInput>
+  let mockSetFailed: MockInstance<typeof core.setFailed>
   const mockOctokit = {
     rest: {
       repos: {
-        listLanguages: jest.fn(),
-        getContent: jest.fn()
+        listLanguages: vi.fn(),
+        getContent: vi.fn()
       }
     }
   }
 
   beforeEach(() => {
-    jest.clearAllMocks()
+    vi.clearAllMocks()
+    mockGetInput = vi.spyOn(core, 'getInput')
+    mockSetFailed = vi.spyOn(core, 'setFailed')
     mockGetInput.mockReturnValue('mock-token')
-    ;(github.getOctokit as jest.Mock).mockReturnValue(mockOctokit)
+    vi.mocked(github.getOctokit).mockReturnValue(mockOctokit)
     Object.defineProperty(github, 'context', {
       value: {
         repo: {