test: Migrate all packages from jest to vitest (#13)

Jest's ESM support sucks
([ref](jestjs/jest#9430)) and is held up on
some interminable issues related to Node VMs
([ref](nodejs/node#37648)). I was impressed
with `vite` and `vitest` following my experience implementing #8, and
after I discovered that `vitest` has a [browser mode for unit
tests](https://vitest.dev/guide/browser/#browser-mode)—which will
ultimately allow us to test under `ses` in an actual browser
environment—I was sold.

This migrates the entire repo from `jest` to `vitest`. They work very
similarly, except [`vitest` has a number of benefits over
`jest`](https://vitest.dev/guide/comparisons.html), such as not
polluting the global namespace by default. I tried running some tests
under `ses` with lockdown in the browser, and it worked perfectly.
However, it's held up on rewriting tests that rely on JSDOM, so we're
tracking that work in #12.

Author: rekmarks

.depcheckrc.yml

@@ -6,11 +6,10 @@ ignores:
   - '@metamask/auto-changelog'
   - '@ts-bridge/cli'
   - '@ts-bridge/shims'
-  - '@types/jest'
   - '@types/node'
   - '@yarnpkg/*'
-  - 'jest-silent-reporter'
   - 'jsdom'
   - 'prettier-plugin-*'
-  - 'ts-jest'
   - 'typedoc'
+  - 'vite'
+  - 'vitest'

.eslintrc.js

@@ -13,7 +13,8 @@ module.exports = {
 
   ignorePatterns: [
     '!.eslintrc.js',
-    '!jest.config.js',
+    '!vite.config.mts',
+    '!vitest.config.mts',
     'node_modules',
     '**/dist',
     '**/docs',
@@ -49,7 +50,7 @@ module.exports = {
     },
 
     {
-      files: ['**/scripts/*.mjs'],
+      files: ['**/scripts/*.mjs', '*.mts'],
       parserOptions: {
         ecmaVersion: '2022',
       },
@@ -98,34 +99,44 @@ module.exports = {
     },
 
     {
-      files: ['**/jest.environment.js'],
+      // @metamask/eslint-plugin-vitest does not exist, so this is copied from the
+      // jest-equivalent. All of the rules we specify are the same. Ref:
+      // https://github.com/MetaMask/eslint-config/blob/95275db568999bf48670894a3dc6b6c1a2f517f9/packages/jest/src/index.js
+      files: ['**/*.test.{ts,js}'],
+      plugins: ['vitest'],
+      extends: ['plugin:vitest/recommended'],
       rules: {
-        // These files run under Node, and thus `require(...)` is expected.
-        'n/global-require': 'off',
-      },
-    },
-
-    {
-      files: ['*.test.{ts,js}', '**/tests/**/*.{ts,js}'],
-      extends: ['@metamask/eslint-config-jest'],
-      rules: {
-        '@typescript-eslint/no-shadow': [
+        // From the jest/style ruleset (no corresponding ruleset for vitest). Ref:
+        // https://github.com/jest-community/eslint-plugin-jest/blob/39719a323466aada48531fe28ec953e17dee6e65/src/index.ts#L74-L77
+        'vitest/no-alias-methods': 'error', // We upgrade this to an error
+        'vitest/prefer-to-be': 'error',
+        'vitest/prefer-to-contain': 'error',
+        'vitest/prefer-to-have-length': 'error',
+        // From MetaMask's custom ruleset
+        'vitest/consistent-test-it': ['error', { fn: 'it' }],
+        'vitest/no-conditional-in-test': 'error', // Previously "jest/no-if"
+        'vitest/no-duplicate-hooks': 'error',
+        'vitest/no-test-return-statement': 'error',
+        'vitest/prefer-hooks-on-top': 'error',
+        'vitest/prefer-lowercase-title': ['error', { ignore: ['describe'] }],
+        'vitest/prefer-spy-on': 'error',
+        'vitest/prefer-strict-equal': 'error',
+        'vitest/prefer-todo': 'error',
+        'vitest/require-top-level-describe': 'error',
+        'vitest/require-to-throw-message': 'error',
+        'vitest/valid-expect': ['error', { alwaysAwait: true }],
+        'vitest/no-restricted-matchers': [
           'error',
-          { allow: ['describe', 'expect', 'it'] },
+          {
+            resolves: 'Use `expect(await promise)` instead.',
+            toBeFalsy: 'Avoid `toBeFalsy`',
+            toBeTruthy: 'Avoid `toBeTruthy`',
+            toMatchSnapshot: 'Use `toMatchInlineSnapshot()` instead',
+            toThrowErrorMatchingSnapshot:
+              'Use `toThrowErrorMatchingInlineSnapshot()` instead',
+          },
         ],
       },
     },
-
-    {
-      // These files are test helpers, not tests. We still use the Jest ESLint
-      // config here to ensure that ESLint expects a test-like environment, but
-      // various rules meant just to apply to tests have been disabled.
-      files: ['**/tests/**/*.{ts,js}', '!*.test.{ts,js}'],
-      rules: {
-        'jest/no-export': 'off',
-        'jest/require-top-level-describe': 'off',
-        'jest/no-if': 'off',
-      },
-    },
   ],
 };

constraints.pro

@@ -299,29 +299,24 @@ gen_enforced_field(WorkspaceCwd, 'scripts.changelog:update', CorrectChangelogUpd
   \+ atom_concat(ExpectedPrefix, _, ChangelogUpdateCommand).
 
 % All non-root packages must have the same "test" script.
-gen_enforced_field(WorkspaceCwd, 'scripts.test', 'jest --reporters=jest-silent-reporter') :-
-  WorkspaceCwd \= 'packages/extension',
+gen_enforced_field(WorkspaceCwd, 'scripts.test', 'vitest run --config vitest.config.mts') :-
   WorkspaceCwd \= 'packages/shims',
   WorkspaceCwd \= '.'.
 
 % All non-root packages must have the same "test:clean" script.
-gen_enforced_field(WorkspaceCwd, 'scripts.test:clean', 'jest --clearCache') :-
-  WorkspaceCwd \= 'packages/extension',
+gen_enforced_field(WorkspaceCwd, 'scripts.test:clean', 'yarn test --no-cache --coverage.clean') :-
   WorkspaceCwd \= '.'.
 
-% All non-root packages must have the same "test:verbose" script.
-gen_enforced_field(WorkspaceCwd, 'scripts.test:verbose', 'jest --verbose') :-
-  WorkspaceCwd \= 'packages/extension',
+% All non-root packages must have the same "test:dev" script.
+gen_enforced_field(WorkspaceCwd, 'scripts.test:dev', 'yarn test --coverage false') :-
   WorkspaceCwd \= '.'.
 
 % All non-root packages must have the same "test:verbose" script.
-gen_enforced_field(WorkspaceCwd, 'scripts.test:dev', 'jest --verbose --coverage false') :-
-  WorkspaceCwd \= 'packages/extension',
+gen_enforced_field(WorkspaceCwd, 'scripts.test:verbose', 'yarn test --reporter verbose') :-
   WorkspaceCwd \= '.'.
 
 % All non-root packages must have the same "test:watch" script.
-gen_enforced_field(WorkspaceCwd, 'scripts.test:watch', 'jest --watch') :-
-  WorkspaceCwd \= 'packages/extension',
+gen_enforced_field(WorkspaceCwd, 'scripts.test:watch', 'vitest --config vitest.config.mts') :-
   WorkspaceCwd \= '.'.
 
 % All dependency ranges must be recognizable (this makes it possible to apply