Let babel-jest handle loading babel config

e2e/__tests__/__snapshots__/logger.test.ts.snap

@@ -49,10 +49,7 @@ Array [
   "[level:20] backporting config",
   "[level:20] normalized jest config",
   "[level:20] normalized ts-jest config",
-  "[level:20] loaded module @babel/core",
-  "[level:20] patching @babel/core",
-  "[level:20] checking version of @babel/core: OK",
-  "[level:20] normalized babel config",
+  "[level:20] normalized babel config via ts-jest option",
   "[level:20] loaded module typescript",
   "[level:20] patching typescript",
   "[level:20] checking version of typescript: OK",
@@ -96,10 +93,7 @@ Array [
   "[level:20] normalized jest config",
   "[level:20] resolved path from babel.config.js to <cwd>/babel.config.js",
   "[level:20] normalized ts-jest config",
-  "[level:20] loaded module @babel/core",
-  "[level:20] patching @babel/core",
-  "[level:20] checking version of @babel/core: OK",
-  "[level:20] normalized babel config",
+  "[level:20] normalized babel config via ts-jest option",
   "[level:20] loaded module typescript",
   "[level:20] patching typescript",
   "[level:20] checking version of typescript: OK",

src/__mocks__/.babelrc-foo

@@ -1,2 +1,7 @@
 {
+  "presets": [
+    "@babel/preset-env",
+    "@babel/preset-typescript",
+    "@babel/preset-react"
+  ],
 }

src/__mocks__/babel-foo.config.js

@@ -1,2 +1,7 @@
 module.exports = {
+  presets: [
+    '@babel/preset-env',
+    '@babel/preset-typescript',
+    '@babel/preset-react',
+  ],
 }

src/config/config-set.spec.ts

@@ -1,6 +1,8 @@
 import { Transformer } from '@jest/transform/build/types'
 import { Config } from '@jest/types'
 import { testing } from 'bs-logger'
+import { readFileSync } from 'fs'
+import json5 = require('json5')
 import { resolve } from 'path'
 import { Diagnostic, DiagnosticCategory, ModuleKind, ParsedCommandLine, ScriptTarget } from 'typescript'
 // tslint:disable-next-line:no-duplicate-imports
@@ -84,6 +86,7 @@ describe('tsJest', () => {
       expect(get().tsConfig).toEqual(EXPECTED)
       expect(get({ tsConfig: true }).tsConfig).toEqual(EXPECTED)
     })
+
     it('should be correct for false', () => {
       expect(get({ tsConfig: false }).tsConfig).toBeUndefined()
     })
@@ -159,35 +162,32 @@ describe('tsJest', () => {
       })
       expect(cs.tsJest.babelConfig!.kind).toEqual('file')
       expect(cs.tsJest.babelConfig!.value).toContain('.babelrc-foo')
-      expect(cs.babel?.plugins).toEqual([])
-      expect(cs.babel?.presets).toEqual([])
+      expect(cs.babel).toEqual(expect.objectContaining(json5.parse(readFileSync(FILE, 'utf8'))))
     })
 
     it('should be correct for given javascript file path', () => {
-      const FILE = 'src/__mocks__/babel-foo.config.js'
       const cs = createConfigSet({
         tsJestConfig: {
-          babelConfig: FILE,
+          babelConfig: 'src/__mocks__/babel-foo.config.js',
         },
         resolve: null,
       })
       expect(cs.tsJest.babelConfig!.kind).toEqual('file')
       expect(cs.tsJest.babelConfig!.value).toContain('babel-foo.config.js')
-      expect(cs.babel?.plugins).toEqual([])
-      expect(cs.babel?.presets).toEqual([])
+      expect(cs.babel).toEqual(expect.objectContaining(require('../__mocks__/babel-foo.config')))
     })
 
     it('should be correct for imported javascript file', () => {
+      const babelConfig = require('../__mocks__/babel-foo.config')
       const cs = createConfigSet({
         jestConfig: { rootDir: 'src', cwd: 'src' } as any,
         tsJestConfig: {
-          babelConfig: require('../__mocks__/babel-foo.config'),
+          babelConfig,
         },
         resolve: null,
       })
       expect(cs.tsJest.babelConfig!.kind).toEqual('inline')
-      expect(cs.babel?.plugins).toEqual([])
-      expect(cs.babel?.presets).toEqual([])
+      expect(cs.babel).toEqual(expect.objectContaining(babelConfig))
     })
 
     it('should be correct for inline config', () => {

src/config/config-set.ts

@@ -13,7 +13,6 @@ import { LogContexts, Logger } from 'bs-logger'
 import { existsSync, readFileSync, realpathSync } from 'fs'
 import json5 = require('json5')
 import { dirname, extname, isAbsolute, join, normalize, resolve } from 'path'
-import semver = require('semver')
 import {
   CompilerOptions,
   CustomTransformers,
@@ -349,24 +348,6 @@ export class ConfigSet {
     }
   }
 
-  private static loadConfig(base: BabelConfig): BabelConfig {
-    // loadPartialConfig is from babel 7+, and OptionManager is backward compatible but deprecated 6 API
-    const { OptionManager, loadPartialConfig, version } = importer.babelCore(ImportReasons.BabelJest)
-    // cwd is only supported from babel >= 7
-    if (version && semver.satisfies(version, '>=6 <7')) {
-      delete base.cwd
-    }
-    // call babel to load options
-    if (typeof loadPartialConfig === 'function') {
-      const partialConfig = loadPartialConfig(base)
-      if (partialConfig) {
-        return partialConfig.options as BabelConfig
-      }
-    }
-
-    return new OptionManager().init(base) as BabelConfig
-  }
-
   @Memoize()
   get babel(): BabelConfig | undefined {
     const {
@@ -394,12 +375,9 @@ export class ConfigSet {
     } else if (babelConfig.kind === 'inline') {
       base = { ...base, ...babelConfig.value }
     }
+    this.logger.debug({ babelConfig: base }, 'normalized babel config via ts-jest option')
 
-    // call babel to load options
-    const config = ConfigSet.loadConfig(base)
-
-    this.logger.debug({ babelConfig: config }, 'normalized babel config')
-    return config
+    return base
   }
 
   @Memoize()