Re-implement per @scotthovestadt's guidance

jestjs · Apr 6, 2019 · b4c5a1f · b4c5a1f
1 parent ad380b4
commit b4c5a1f
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Showing 2 changed files with 38 additions and 8 deletions.
diff --git a/packages/jest-runtime/src/index.ts b/packages/jest-runtime/src/index.ts
@@ -27,6 +27,7 @@ import {
   shouldInstrument,
 } from '@jest/transform';
 import fs from 'graceful-fs';
+import stripBOM from 'strip-bom';
 import {run as cliRun} from './cli';
 import {options as cliOptions} from './cli/args';
 import {findSiblingsWithFileExtension} from './helpers';
@@ -463,7 +464,19 @@ class Runtime {
     options: InternalModuleOptions | undefined,
     moduleRegistry: ModuleRegistry,
   ) {
-    if (path.extname(modulePath) === '.node') {
+    if (path.extname(modulePath) === '.json') {
+      const text = stripBOM(fs.readFileSync(modulePath, 'utf8'));
+
+      const transformedFile = this._scriptTransformer.transformJson(
+        modulePath,
+        options,
+        text,
+      );
+
+      localModule.exports = this._environment.global.JSON.parse(
+        transformedFile,
+      );
+    } else if (path.extname(modulePath) === '.node') {
       localModule.exports = require(modulePath);
     } else {
       // Only include the fromPath if a moduleName is given. Else treat as root.

diff --git a/packages/jest-transform/src/ScriptTransformer.ts b/packages/jest-transform/src/ScriptTransformer.ts
@@ -331,8 +331,6 @@ export default class ScriptTransformer {
       !isInternalModule &&
       !isCoreModule &&
       (this.shouldTransform(filename) || instrument);
-    const isJson = path.extname(filename) === '.json';
-    const prefix = isJson ? 'module.exports = ' : '';
 
     try {
       const extraGlobals = (options && options.extraGlobals) || [];
@@ -344,14 +342,11 @@ export default class ScriptTransformer {
           instrument,
         );
 
-        wrappedCode = wrap(
-          `${prefix}${transformedSource.code}`,
-          ...extraGlobals,
-        );
+        wrappedCode = wrap(transformedSource.code, ...extraGlobals);
         sourceMapPath = transformedSource.sourceMapPath;
         mapCoverage = transformedSource.mapCoverage;
       } else {
-        wrappedCode = wrap(`${prefix}${content}`, ...extraGlobals);
+        wrappedCode = wrap(content, ...extraGlobals);
       }
 
       return {
@@ -410,6 +405,28 @@ export default class ScriptTransformer {
     return result;
   }
 
+  transformJson(
+    filename: Config.Path,
+    options: Pick<Options, 'isInternalModule' | 'isCoreModule'> | undefined,
+    fileSource: string,
+  ): string {
+    const isInternalModule = !!(options && options.isInternalModule);
+    const isCoreModule = !!(options && options.isCoreModule);
+    const willTransform =
+      !isInternalModule && !isCoreModule && this.shouldTransform(filename);
+
+    if (willTransform) {
+      const {code: transformedJsonSource} = this.transformSource(
+        filename,
+        fileSource,
+        false,
+      );
+      return transformedJsonSource;
+    }
+
+    return fileSource;
+  }
+
   /**
    * @deprecated use `this.shouldTransform` instead
    */