Detect file type before read as stream

src/io/directory.js

@@ -59,11 +59,21 @@ export class Directory extends IOBase {
   getFileAsStream(relativeFilePath) {
     return this.getPath(relativeFilePath)
       .then((filePath) => {
-        return Promise.resolve(createReadStream(filePath, {
+        const opt = {
           flags: 'r',
-          encoding: 'utf8',
+          encoding: null,
           autoClose: true,
-        }).pipe(stripBomStream()));
+        };
+        const isAscii =
+          /\.(?:css|html?|js(?:on)?|mml|svg|txt|x(?:ht)?ml)$/i.test(filePath);
+        let func;
+        if (isAscii) {
+          opt.encoding = 'utf8';
+          func = createReadStream(filePath, opt).pipe(stripBomStream());
+        } else {
+          func = createReadStream(filePath, opt);
+        }
+        return Promise.resolve(func);
       });
   }
 

tests/io/test.directory.js

@@ -1,10 +1,11 @@
 import { EventEmitter } from 'events';
 
+import probeImageSize from 'probe-image-size';
+
 import { Directory } from 'io';
 
 import { unexpectedSuccess } from '../helpers';
 
-
 describe('Directory.getFiles()', () => {
   it('should return cached data when available', () => {
     const myDirectory = new Directory('tests/fixtures/io/');
@@ -112,7 +113,7 @@ describe('Directory._getPath()', () => {
 });
 
 describe('Directory.getFileAsStream()', () => {
-  it('should return a stream', () => {
+  it('should return a readable stream', () => {
     const myDirectory = new Directory('tests/fixtures/io/');
     return myDirectory.getFiles()
       .then(() => {
@@ -142,6 +143,19 @@ describe('Directory.getFileAsStream()', () => {
       });
   });
 
+  it('should return a binary stream', () => {
+    const myDirectory = new Directory('tests/fixtures/io/');
+    return myDirectory.getFiles()
+      .then(() => {
+        return myDirectory.getFileAsStream('dir2/dir3/test.png');
+      })
+      .then(probeImageSize)
+      .then((result) => {
+        const { mime } = result;
+        expect(mime).toEqual('image/png');
+      });
+  });
+
   it('should reject if file is too big', () => {
     const myDirectory = new Directory('tests/fixtures/io/');
     const fakeFileMeta = {