feat(config/test): use **@swc/jest** as default Jest transform

BREAKING CHANGE: **@swc/jest** is now the default Jest transform and
**ts-jest** is no longer installed by default. To preserve the old transform
behavior, install **ts-jest** as a \`devDependency\` in you project. ∙ BREAKING
CHANGE: the \`@hover/javascript/api/test\` API has been removed as **ts-jest**
is no longer installed by default. If you're still using **ts-jest**, import
its helpers directly from **ts-jest** instead of the \`/api/test\` entrypoint.

jest.config.js

@@ -1,6 +1,5 @@
 const {
   globals,
-  transform,
   transformIgnorePatterns,
   ...config
 } = require('./src/config/jest.config')
@@ -11,13 +10,4 @@ module.exports = {
   roots: ['<rootDir>/src'],
   coverageThreshold: null,
   transformIgnorePatterns: [...transformIgnorePatterns, '.prettierrc.js'],
-  // Specifying ts-jest options via `global` in Jest configuration has been
-  // deprecated so we have to do this in order to add the `exclude` option to
-  // the transform in our Jest configuration that already has `transform` ☹
-  transform: Object.fromEntries(
-    Object.entries(transform).map(([glob, [transformer, options]]) => [
-      glob,
-      [transformer, {...options, exclude: '**/*'}],
-    ]),
-  ),
 }

package.json

@@ -53,6 +53,8 @@
     "@commitlint/cli": "^16.1.0",
     "@commitlint/config-conventional": "^16.2.1",
     "@commitlint/prompt": "^16.1.0",
+    "@swc/core": "^1.2.248",
+    "@swc/jest": "^0.2.22",
     "@types/jest": "^29.0.0",
     "@types/lodash.has": "^4.5.6",
     "@types/mkdirp": "^1.0.2",
@@ -89,7 +91,6 @@
     "prettier": "^2.5.1",
     "read-pkg-up": "^7.0.1",
     "rimraf": "^3.0.2",
-    "ts-jest": "^29.0.0-next.1",
     "tslib": "^2.4.0",
     "typescript": "^4",
     "which": "^2.0.2",
@@ -136,5 +137,13 @@
     "jest-in-case": "^1.0.2",
     "npm-run-all": "^4.1.5",
     "slash": "^3.0.0"
+  },
+  "peerDependencies": {
+    "ts-jest": "^29.0.0"
+  },
+  "peerDependenciesMeta": {
+    "ts-jest": {
+      "optional": true
+    }
   }
 }

src/config/jest.config.js

@@ -1,8 +1,6 @@
 /** @typedef {import('@jest/types').Config.InitialOptions} JestConfig */
 
-const {jsWithTs: preset} = require('ts-jest/presets')
-
-const {ifAnyDep, hasFile, fromRoot} = require('../utils')
+const {ifAnyDep, hasFile, fromRoot, hasDevDep} = require('../utils')
 
 const {
   testMatch,
@@ -33,14 +31,20 @@ const jestConfig = {
   testMatch,
   testPathIgnorePatterns: [...ignores, '<rootDir>/dist'],
   testLocationInResults: true,
-  transform: Object.fromEntries(
-    // Ensure we can resolve the preset even when
-    // it's in a nested `node_modules` installation
-    Object.entries(preset.transform).map(([glob, transformer]) => [
-      glob,
-      [require.resolve(transformer), {diagnostics: {warnOnly: true}}],
-    ]),
-  ),
+  // The default transform is now SWC, however, `ts-jest` will
+  // still be used if it is installed in the host project
+  transform: hasDevDep('ts-jest')
+    ? Object.fromEntries(
+        // Ensure we can resolve the preset even when
+        // it's in a nested `node_modules` installation
+        Object.entries(require('ts-jest/presets').transform).map(
+          ([glob, transformer]) => [
+            glob,
+            [require.resolve(transformer), {diagnostics: {warnOnly: true}}],
+          ],
+        ),
+      )
+    : {'^.+\\.(t|j)sx?$': ['@swc/jest']},
   coveragePathIgnorePatterns: [
     ...ignores,
     'src/(umd|cjs|esm)-entry.js$',
@@ -63,10 +67,9 @@ const jestConfig = {
     require.resolve('jest-watch-typeahead/filename'),
     require.resolve('jest-watch-typeahead/testname'),
   ],
-}
-
-if (hasFile('tests/setup-env.js')) {
-  jestConfig.setupFilesAfterEnv = [fromRoot('tests/setup-env.js')]
+  setupFilesAfterEnv: hasFile('tests/setup-env.js')
+    ? [fromRoot('tests/setup-env.js')]
+    : undefined,
 }
 
 module.exports = jestConfig

src/utils.js

@@ -244,6 +244,7 @@ module.exports = {
   getConcurrentlyArgs,
   getPkgName,
   hasAnyDep,
+  hasDevDep,
   hasFile,
   hasLocalConfig,
   hasPkgProp,