metro-buck: do not transform non-source files

Reviewed By: davidaurelio

Differential Revision: D6666127

fbshipit-source-id: ba20664da81361fadb8119bfeb858c70a7500c14

packages/metro/src/ModuleGraph/types.flow.js

@@ -228,6 +228,9 @@ export type TransformedSourceFile =
   | {|
       +type: 'asset',
       +details: AssetFile,
+    |}
+  | {|
+      +type: 'unknown',
     |};
 
 export type LibraryOptions = {|

packages/metro/src/ModuleGraph/worker/__tests__/optimize-module-test.js

@@ -26,6 +26,7 @@ const {objectContaining} = jasmine;
 
 describe('optimizing JS modules', () => {
   const filename = 'arbitrary/file.js';
+  const sourceExts = new Set(['js', 'json']);
   const optimizationOptions = {
     dev: false,
     platform: 'android',
@@ -42,7 +43,9 @@ describe('optimizing JS modules', () => {
 
   let transformResult;
   beforeAll(() => {
-    const result = transformModule(originalCode, {filename, transformer});
+    const trOpts = {filename, sourceExts, transformer};
+    const result = transformModule(originalCode, trOpts);
+    invariant(result.type === 'code', 'result must be code');
     transformResult = new Buffer(
       JSON.stringify({type: 'code', details: result.details}),
       'utf8',
@@ -53,7 +56,7 @@ describe('optimizing JS modules', () => {
     const result = optimizeModule(transformResult, optimizationOptions);
     const expected = JSON.parse(transformResult.toString('utf8')).details;
     delete expected.transformed;
-    expect(result.type).toBe('code');
+    invariant(result.type === 'code', 'result must be code');
     expect(result.details).toEqual(objectContaining(expected));
   });
 

packages/metro/src/ModuleGraph/worker/__tests__/transform-module-test.js

@@ -31,7 +31,8 @@ jest.mock('image-size', () => buffer => {
 });
 
 describe('transforming JS modules:', () => {
-  const filename = 'arbitrary';
+  const filename = 'arbitrary.js';
+  const sourceExts = new Set(['js', 'json']);
 
   let transformer;
 
@@ -47,6 +48,7 @@ describe('transforming JS modules:', () => {
 
   const options = (variants?: TransformVariants) => ({
     filename,
+    sourceExts,
     transformer,
     variants,
   });
@@ -57,7 +59,7 @@ describe('transforming JS modules:', () => {
 
   it('passes through file name', () => {
     const result = transformModule(sourceCode, options());
-    expect(result.type).toBe('code');
+    invariant(result.type === 'code', 'result must be code');
     expect(result.details).toEqual(
       expect.objectContaining({
         file: filename,
@@ -69,19 +71,19 @@ describe('transforming JS modules:', () => {
     const hasteID = 'TheModule';
     const codeWithHasteID = toBuffer(`/** @providesModule ${hasteID} */`);
     const result = transformModule(codeWithHasteID, options());
-    expect(result.type).toBe('code');
+    invariant(result.type === 'code', 'result must be code');
     expect(result.details).toEqual(expect.objectContaining({hasteID}));
   });
 
   it('sets `type` to `"module"` by default', () => {
     const result = transformModule(sourceCode, options());
-    expect(result.type).toBe('code');
+    invariant(result.type === 'code', 'result must be code');
     expect(result.details).toEqual(expect.objectContaining({type: 'module'}));
   });
 
   it('sets `type` to `"script"` if the input is a polyfill', () => {
     const result = transformModule(sourceCode, {...options(), polyfill: true});
-    expect(result.type).toBe('code');
+    invariant(result.type === 'code', 'result must be code');
     expect(result.details).toEqual(expect.objectContaining({type: 'script'}));
   });
 
@@ -240,6 +242,14 @@ describe('transforming JS modules:', () => {
     expect(result.details.package).toEqual(pkg);
   });
 
+  it('does not process non-source files', () => {
+    const result = transformModule(toBuffer('arbitrary'), {
+      ...options(),
+      filename: 'some.yy',
+    });
+    invariant(result.type === 'unknown', 'result must be code');
+  });
+
   describe('assets', () => {
     it('extract image sizes, platform, scale', () => {
       const image = {__size: {width: 30, height: 20}};

packages/metro/src/ModuleGraph/worker/transform-module.js

@@ -42,6 +42,7 @@ export type TransformOptions<ExtraOptions> = {|
   filename: string,
   hasteImpl?: HasteImpl,
   polyfill?: boolean,
+  +sourceExts: Set<string>,
   transformer: Transformer<ExtraOptions>,
   variants?: TransformVariants,
 |};
@@ -63,15 +64,18 @@ function transformModule(
   content: Buffer,
   options: TransformOptions<{+retainLines?: boolean}>,
 ): TransformedSourceFile {
-  if (ASSET_EXTENSIONS.has(path.extname(options.filename).substr(1))) {
+  const ext = path.extname(options.filename).substr(1);
+  if (ASSET_EXTENSIONS.has(ext)) {
     return transformAsset(content, options.filename);
   }
+  if (ext === 'json') {
+    return transformJSON(content.toString('utf8'), options);
+  }
+  if (!options.sourceExts.has(ext)) {
+    return {type: 'unknown'};
+  }
 
   const code = content.toString('utf8');
-  if (options.filename.endsWith('.json')) {
-    return transformJSON(code, options);
-  }
-
   const {filename, transformer, polyfill, variants = defaultVariants} = options;
   const transformed: {[key: string]: TransformResult} = {};