feat(@jest/transform)!: require process() and processAsync() methods to always return structured data

e2e/__tests__/dependencyClash.test.ts

@@ -64,10 +64,12 @@ test('does not require project modules from inside node_modules', () => {
           if (!threw) {
             throw new Error('It used the wrong invariant module!');
           }
-          return script.replace(
-            'INVALID CODE FRAGMENT THAT WILL BE REMOVED BY THE TRANSFORMER',
-            ''
-          );
+          return {
+            code: script.replace(
+              'INVALID CODE FRAGMENT THAT WILL BE REMOVED BY THE TRANSFORMER',
+              '',
+            ),
+          };
         },
       };
     `,

e2e/coverage-provider-v8/esm-with-custom-transformer/typescriptPreprocessor.js

@@ -21,6 +21,6 @@ export default {
 
       return {code: outputText, map: sourceMapText};
     }
-    return sourceText;
+    return {code: sourceText};
   },
 };

e2e/coverage-provider-v8/no-sourcemap/cssTransform.js

@@ -7,5 +7,5 @@
 
 module.exports = {
   getCacheKey: () => 'cssTransform',
-  process: () => 'module.exports = {};',
+  process: () => ({code: 'module.exports = {};'}),
 };

e2e/coverage-remapping/typescriptPreprocessor.js

@@ -22,6 +22,6 @@ module.exports = {
         map: JSON.parse(result.sourceMapText),
       };
     }
-    return src;
+    return {code: src};
   },
 };

e2e/global-setup-custom-transform/transformer.js

@@ -12,9 +12,9 @@ const fileToTransform = require.resolve('./index.js');
 module.exports = {
   process(src, filename) {
     if (filename === fileToTransform) {
-      return src.replace('hello', 'hello, world');
+      return {code: src.replace('hello', 'hello, world')};
     }
 
-    return src;
+    return {code: src};
   },
 };

e2e/snapshot-serializers/transformer.js

@@ -10,8 +10,8 @@
 module.exports = {
   process(src, filename) {
     if (/bar.js$/.test(filename)) {
-      return `${src};\nmodule.exports = createPlugin('bar');`;
+      return {code: `${src};\nmodule.exports = createPlugin('bar');`};
     }
-    return src;
+    return {code: src};
   },
 };

e2e/stack-trace-source-maps-with-coverage/preprocessor.js

@@ -8,14 +8,19 @@
 const tsc = require('typescript');
 
 module.exports = {
-  process(src, path) {
-    return tsc.transpileModule(src, {
-      compilerOptions: {
-        inlineSourceMap: true,
-        module: tsc.ModuleKind.CommonJS,
-        target: 'es5',
-      },
-      fileName: path,
-    }).outputText;
+  process(sourceText, fileName) {
+    if (fileName.endsWith('.ts') || fileName.endsWith('.tsx')) {
+      const {outputText, sourceMapText} = tsc.transpileModule(sourceText, {
+        compilerOptions: {
+          inlineSourceMap: true,
+          module: tsc.ModuleKind.CommonJS,
+          target: 'es5',
+        },
+        fileName,
+      });
+
+      return {code: outputText, map: sourceMapText};
+    }
+    return {code: sourceText};
   },
 };

e2e/stack-trace-source-maps/preprocessor.js

@@ -8,14 +8,19 @@
 const tsc = require('typescript');
 
 module.exports = {
-  process(src, path) {
-    return tsc.transpileModule(src, {
-      compilerOptions: {
-        inlineSourceMap: true,
-        module: tsc.ModuleKind.CommonJS,
-        target: 'es5',
-      },
-      fileName: path,
-    }).outputText;
+  process(sourceText, fileName) {
+    if (fileName.endsWith('.ts') || fileName.endsWith('.tsx')) {
+      const {outputText, sourceMapText} = tsc.transpileModule(sourceText, {
+        compilerOptions: {
+          inlineSourceMap: true,
+          module: tsc.ModuleKind.CommonJS,
+          target: 'es5',
+        },
+        fileName,
+      });
+
+      return {code: outputText, map: sourceMapText};
+    }
+    return {code: sourceText};
   },
 };

e2e/transform-linked-modules/preprocessor.js

@@ -7,6 +7,6 @@
 
 module.exports = {
   process() {
-    return 'module.exports = "transformed"';
+    return {code: 'module.exports = "transformed"'};
   },
 };

e2e/transform/async-transformer/my-transform.cjs

@@ -24,12 +24,14 @@ module.exports = {
       // we want to wait to ensure the module cache is populated with the correct module
       await wait(100);
 
-      return src;
+      return {code: src};
     }
 
-    return src.replace(
-      "export default 'It was not transformed!!'",
-      'export default 42',
-    );
+    return {
+      code: src.replace(
+        "export default 'It was not transformed!!'",
+        'export default 42',
+      ),
+    };
   },
 };

e2e/transform/cache/transformer.js

@@ -6,11 +6,11 @@
  */
 
 module.exports = {
-  process(src, path) {
+  process(code, path) {
     if (path.includes('common')) {
       console.log(path);
     }
 
-    return src;
+    return {code};
   },
 };

e2e/transform/custom-instrumenting-preprocessor/preprocessor.js

@@ -8,12 +8,12 @@
 module.exports = {
   canInstrument: true,
   process(src, filename, options) {
-    src = `${src};\nglobalThis.__PREPROCESSED__ = true;`;
+    let code = `${src};\nglobalThis.__PREPROCESSED__ = true;`;
 
     if (options.instrument) {
-      src = `${src};\nglobalThis.__INSTRUMENTED__ = true;`;
+      code = `${src};\nglobalThis.__INSTRUMENTED__ = true;`;
     }
 
-    return src;
+    return {code};
   },
 };

e2e/transform/esm-transformer/my-transform.mjs

@@ -14,9 +14,9 @@ const fileToTransform = require.resolve('./module');
 export default {
   process(src, filepath) {
     if (filepath === fileToTransform) {
-      return 'module.exports = 42;';
+      return {code: 'module.exports = 42;'};
     }
 
-    return src;
+    return {code: src};
   },
 };

e2e/transform/multiple-transformers/cssPreprocessor.js

@@ -7,13 +7,15 @@
 
 module.exports = {
   process() {
-    return `
-      module.exports = {
-        root: 'App-root',
-        header: 'App-header',
-        logo: 'App-logo',
-        intro: 'App-intro',
-      };
-    `;
+    const code = `
+    module.exports = {
+      root: 'App-root',
+      header: 'App-header',
+      logo: 'App-logo',
+      intro: 'App-intro',
+    };
+  `;
+
+    return {code};
   },
 };

e2e/transform/multiple-transformers/filePreprocessor.js

@@ -9,8 +9,10 @@ const path = require('path');
 
 module.exports = {
   process(src, filename) {
-    return `
-      module.exports = '${path.basename(filename)}';
-    `;
+    const code = `
+    module.exports = '${path.basename(filename)}';
+  `;
+
+    return {code};
   },
 };

e2e/typescript-coverage/typescriptPreprocessor.js

@@ -8,18 +8,19 @@
 const tsc = require('typescript');
 
 module.exports = {
-  process(src, path) {
-    if (path.endsWith('.ts') || path.endsWith('.tsx')) {
-      return tsc.transpile(
-        src,
-        {
+  process(sourceText, fileName) {
+    if (fileName.endsWith('.ts') || fileName.endsWith('.tsx')) {
+      const {outputText, sourceMapText} = tsc.transpileModule(sourceText, {
+        compilerOptions: {
           jsx: tsc.JsxEmit.React,
           module: tsc.ModuleKind.CommonJS,
+          sourceMap: true, // if code is transformed, source map is necessary for coverage
         },
-        path,
-        [],
-      );
+        fileName,
+      });
+
+      return {code: outputText, map: sourceMapText};
     }
-    return src;
+    return {code: sourceText};
   },
 };

packages/babel-jest/src/index.ts

@@ -244,7 +244,7 @@ export const createTransformer: TransformerCreator<
         }
       }
 
-      return sourceText;
+      return {code: sourceText};
     },
     async processAsync(sourceText, sourcePath, transformOptions) {
       const babelOptions = await loadBabelOptionsAsync(
@@ -266,7 +266,7 @@ export const createTransformer: TransformerCreator<
         }
       }
 
-      return sourceText;
+      return {code: sourceText};
     },
   };
 };

packages/jest-runtime/src/__tests__/test_root/test_json_preprocessor.js

@@ -10,5 +10,5 @@
 module.exports.process = source => {
   const json = JSON.parse(source);
   Object.keys(json).forEach(k => (json[k] = k));
-  return JSON.stringify(json);
+  return {code: JSON.stringify(json)};
 };

packages/jest-runtime/src/__tests__/test_root/test_preprocessor.js

@@ -7,4 +7,6 @@
 
 'use strict';
 
-module.exports.process = () => "throw new Error('preprocessor must not run.');";
+module.exports.process = () => ({
+  code: "throw new Error('preprocessor must not run.');",
+});

packages/jest-transform/src/ScriptTransformer.ts

@@ -379,9 +379,7 @@ class ScriptTransformer {
     };
 
     if (transformer && shouldCallTransform) {
-      if (typeof processed === 'string') {
-        transformed.code = processed;
-      } else if (processed != null && typeof processed.code === 'string') {
+      if (processed != null && typeof processed.code === 'string') {
         transformed = processed;
       } else {
         throw new Error(makeInvalidReturnValueError());
@@ -483,7 +481,7 @@ class ScriptTransformer {
       };
     }
 
-    let processed = null;
+    let processed: TransformedSource | null = null;
 
     let shouldCallTransform = false;