always return object from babel-jest transform

CHANGELOG.md

@@ -108,6 +108,8 @@
 
 ### Chore & Maintenance
 
+* `[babel-jest]` [**BREAKING**] Always return object from transformer
+  ([#5991](https://github.com/facebook/jest/pull/5991))
 * `[jest-jasmine2]` Simplify `Env.execute` and TreeProcessor to setup and clean
   resources for the top suite the same way as for all of the children suites
   ([#5885](https://github.com/facebook/jest/pull/5885))

packages/babel-jest/src/__tests__/index.js

@@ -31,39 +31,6 @@ const mockConfig = {
 
 test(`Returns source string with inline maps when no transformOptions is passed`, () => {
   const result = babelJest.process(sourceString, 'dummy_path.js', mockConfig);
-  expect(typeof result).toBe('string');
-  expect(result).toMatch('//# sourceMappingURL');
-  expect(result).toMatch('customMultiply');
-});
-
-test(`Returns source string with inline maps when transformOptions
- is passed but doesn't have returnSourceString passed`, () => {
-  const result = babelJest.process(
-    sourceString,
-    'dummy_path.js',
-    mockConfig,
-    {},
-  );
-  expect(typeof result).toBe('string');
-  expect(result).toMatch('//# sourceMappingURL');
-  expect(result).toMatch('customMultiply');
-});
-
-test(`Returns source string with inline maps when transformOptions
- is passed and returnSourceString is true`, () => {
-  const result = babelJest.process(sourceString, 'dummy_path.js', mockConfig, {
-    returnSourceString: true,
-  });
-  expect(typeof result).toBe('string');
-  expect(result).toMatch('//# sourceMappingURL');
-  expect(result).toMatch('customMultiply');
-});
-
-test(`Returns source string with inline maps when transformOptions
- is passed and returnSourceString is false`, () => {
-  const result = babelJest.process(sourceString, 'dummy_path.js', mockConfig, {
-    returnSourceString: false,
-  });
   expect(typeof result).toBe('object');
   expect(result.code).toBeDefined();
   expect(result.map).toBeDefined();

packages/babel-jest/src/index.js

@@ -135,16 +135,7 @@ const createTransformer = (options: any): Transformer => {
       // babel v7 might return null in the case when the file has been ignored.
       const transformResult = babelTransform(src, theseOptions);
 
-      if (!transformResult) {
-        return src;
-      }
-
-      const shouldReturnCodeOnly =
-        transformOptions == null ||
-        transformOptions.returnSourceString == null ||
-        transformOptions.returnSourceString === true;
-
-      return shouldReturnCodeOnly ? transformResult.code : transformResult;
+      return transformResult || src;
     },
   };
 };

packages/jest-runtime/src/script_transformer.js

@@ -217,7 +217,6 @@ export default class ScriptTransformer {
     if (transform && shouldCallTransform) {
       const processed = transform.process(content, filename, this._config, {
         instrument,
-        returnSourceString: false,
       });
 
       if (typeof processed === 'string') {

types/Transform.js

@@ -23,7 +23,6 @@ export type TransformResult = {|
 
 export type TransformOptions = {|
   instrument: boolean,
-  returnSourceString?: boolean,
 |};
 
 export type CacheKeyOptions = {|