chore(jest-types): expose TransformedSource for transformers

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 ### Chore & Maintenance
 
+- `[@jest/transform]` Expose type `TransformedSource` ([#9736](https://github.com/facebook/jest/pull/9736))
+
 ### Performance
 
 ## 25.2.4
@@ -17,7 +19,7 @@
 ### Fixes
 
 - `[jest-circus]` Fix type elision of jest-runtime imports ([#9717](https://github.com/facebook/jest/pull/9717))
-- `[@jest/transform]` Fix coverage reporter for uncovered files without transformers, reverting ([#9460](https://github.com/facebook/jest/pull/9460)) ([#9724](https://github.com/facebook/jest/pull/9724))
+- `[@jest/transform]` Fix coverage reporter for uncovered files without transformers, reverting [#9460](https://github.com/facebook/jest/pull/9460) ([#9724](https://github.com/facebook/jest/pull/9724))
 
 ## 25.2.3
 

packages/jest-transform/src/index.ts

@@ -15,5 +15,6 @@ export type {
   ShouldInstrumentOptions,
   Options as TransformationOptions,
   TransformResult,
+  TransformedSource,
 } from './types';
 export {default as handlePotentialSyntaxError} from './enhanceUnexpectedTokenMessage';

packages/jest-transform/src/types.ts

@@ -32,10 +32,9 @@ interface FixedRawSourceMap extends SourceMapWithVersion {
   version: number;
 }
 
-export type TransformedSource = {
-  code: string;
-  map?: FixedRawSourceMap | string | null;
-};
+export type TransformedSource =
+  | {code: string; map?: FixedRawSourceMap | string | null}
+  | string;
 
 export type TransformResult = {
   code: string;
@@ -70,5 +69,5 @@ export interface Transformer {
     sourcePath: Config.Path,
     config: Config.ProjectConfig,
     options?: TransformOptions,
-  ) => string | TransformedSource;
+  ) => TransformedSource;
 }