accept non-inline source maps from transformers

packages/jest-runtime/src/transform.js

@@ -10,7 +10,7 @@
 'use strict';
 
 import type {Config, Path} from 'types/Config';
-import type {Transformer} from 'types/Transform';
+import type {Transformer, TransformedSource} from 'types/Transform';
 
 const createDirectory = require('jest-util').createDirectory;
 const crypto = require('crypto');
@@ -235,7 +235,7 @@ const stripShebang = content => {
 };
 
 const instrumentFile = (
-  content: string,
+  transformedSource: TransformedSource,
   filename: Path,
   config: Config,
 ): string => {
@@ -244,7 +244,7 @@ const instrumentFile = (
   const babel = require('babel-core');
   const babelPluginIstanbul = require('babel-plugin-istanbul').default;
 
-  return babel.transform(content, {
+  return babel.transform(transformedSource.content, {
     auxiliaryCommentBefore: ' istanbul ignore next ',
     babelrc: false,
     filename,
@@ -254,6 +254,7 @@ const instrumentFile = (
         {
           cwd: config.rootDir, // files outside `cwd` will not be instrumented
           exclude: [],
+          inputSourceMap: transformedSource.sourceMap,
         },
       ],
     ],
@@ -276,21 +277,32 @@ const transformSource = (
     return result;
   }
 
-  result = content;
+  let transformed: TransformedSource = {
+    content,
+    sourceMap: null,
+  };
 
   if (transform && shouldTransform(filename, config)) {
-    result = transform.process(result, filename, config, {
+    const processed = transform.process(content, filename, config, {
       instrument,
       watch: config.watch,
     });
+
+    if (typeof processed === 'string') {
+      transformed.content = processed;
+    } else {
+      transformed = processed;
+    }
   }
 
   // That means that the transform has a custom instrumentation
   // logic and will handle it based on `config.collectCoverage` option
-  const transformWillInstrument = transform && transform.canInstrument;
+  const transformDidInstrument = transform && transform.canInstrument;
 
-  if (!transformWillInstrument && instrument) {
-    result = instrumentFile(result, filename, config);
+  if (!transformDidInstrument && instrument) {
+    result = instrumentFile(transformed, filename, config);
+  } else {
+    result = transformed.content;
   }
 
   writeCacheFile(cacheFilePath, result);

types/Transform.js

@@ -11,6 +11,11 @@
 
 import type {Config, Path} from 'types/Config';
 
+export type TransformedSource = {|
+  content: string,
+  sourceMap: ?string,
+|};
+
 export type SourceMap = {|
   file: string,
   mappings: string,
@@ -41,5 +46,5 @@ export type Transformer = {|
     sourcePath: Path,
     config: Config,
     options?: TransformOptions,
-  ) => string,
+  ) => string | TransformedSource,
 |};