fix(config/jest): set ts-jest transform unconditionally

No alternative is provided, so this would break things anyways unless
a dependent project provided its own transform. This unambiguously makes
`ts-jest` the default transform and project can always explicitly override
the transform in its `jest.config`

Author: jrolfs

package.json

@@ -125,7 +125,6 @@
     "@babel/core": "^7.16.0",
     "@babel/preset-env": "^7.16.11",
     "@types/cross-spawn": "^6.0.2",
-    "babel-jest": "^27.2.4",
     "eslint-config-kentcdodds": "^20.0.1",
     "husky": "^7.0.4",
     "jest-in-case": "^1.0.2",

src/config/jest.config.js

@@ -2,7 +2,7 @@
 
 const {jsWithTs: preset} = require('ts-jest/presets')
 
-const {ifAnyDep, hasAnyDep, hasFile, fromRoot} = require('../utils')
+const {ifAnyDep, hasFile, fromRoot} = require('../utils')
 
 const {
   testMatch,
@@ -29,6 +29,14 @@ 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(([key, value]) => [
+      key,
+      require.resolve(value),
+    ]),
+  ),
   coveragePathIgnorePatterns: [
     ...ignores,
     'src/(umd|cjs|esm)-entry.js$',
@@ -51,24 +59,13 @@ const jestConfig = {
     require.resolve('jest-watch-typeahead/filename'),
     require.resolve('jest-watch-typeahead/testname'),
   ],
-  globals: {},
-}
-
-if (hasAnyDep('ts-jest') || hasFile('tsconfig.json')) {
-  jestConfig.transform = Object.fromEntries(
-    // Ensure we can resolve the preset even when
-    // it's in a nested `node_modules` installation
-    Object.entries(preset.transform).map(([key, value]) => [
-      key,
-      require.resolve(value),
-    ]),
-  )
-
-  jestConfig.globals['ts-jest'] = {
-    diagnostics: {
-      warnOnly: true,
+  globals: {
+    'ts-jest': {
+      diagnostics: {
+        warnOnly: true,
+      },
     },
-  }
+  },
 }
 
 if (hasFile('tests/setup-env.js')) {