Update babel getter to work with babel-jest@24

babel-jest@24 will also use loadPartialConfig to be able to mix its own options into the config in an API-conforming manner. However, loadPartialConfig will throw an assertion error if the config has not only been loaded, but also had its plugins instantiatied. loadOptions() does the whole thing, including instantiating the plugins, so it can't be used for multiple config loading passes, only the final pass.

src/config/config-set.ts

@@ -336,16 +336,16 @@ export class ConfigSet {
       base = { ...base, ...babelConfig.value }
     }
 
-    // loadOptions is from babel 7+, and OptionManager is backward compatible but deprecated 6 API
-    const { OptionManager, loadOptions, version } = importer.babelCore(ImportReasons.BabelJest)
+    // 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
     let config: BabelConfig
-    if (typeof loadOptions === 'function') {
-      config = loadOptions(base) as BabelConfig
+    if (typeof loadPartialConfig === 'function') {
+      config = loadPartialConfig(base).options as BabelConfig
     } else {
       config = new OptionManager().init(base) as BabelConfig
     }