fix(image-stream): Remove inability to fallback to octet-stream (#1363)

Using `mime-types` in that place made it impossible to use other
other file extensions like `.sdcard` and have them treated as `application/octet-stream`
when drag and dropping images into Etcher.

This moves the fallback logic in `lib/image-stream` to `.getFromFilePath()`,
to still facilitate proper MIME type detection, while allowing it to fall back
to the octet-stream handler, if there's no available handler for a specific type.

Change-Type: patch
Changelog-Entry: Fix not treating unknown images as octet-stream

.gitattributes

@@ -32,3 +32,4 @@ Makefile text
 *.xz binary
 *.zip binary
 *.dmg binary
+*.rpi-sdcard binary

lib/image-stream/index.js

@@ -76,14 +76,9 @@ exports.getFromFilePath = (file) => {
     }
 
     return utils.getArchiveMimeType(file).then((type) => {
-      if (!_.has(handlers, type)) {
+      const MIME_TYPE_RAW_IMAGE = 'application/octet-stream';
-        throw errors.createUserError({
+      const mimeType = _.has(handlers, type) ? type : MIME_TYPE_RAW_IMAGE;
-          title: 'Invalid image',
+      return _.invoke(handlers, mimeType, file, {
-          description: `The ${type} format is not supported`
-        });
-      }
-
-      return _.invoke(handlers, type, file, {
         size: fileStats.size
       });
     });

lib/image-stream/utils.js

@@ -41,10 +41,6 @@ exports.getArchiveMimeType = (filename) => {
   const mimeType = mime.lookup(filename);
 
   if (mimeType) {
-    if (mimeType === 'application/x-iso9660-image') {
-      return Bluebird.resolve(MIME_TYPE_RAW_IMAGE);
-    }
-
     return Bluebird.resolve(mimeType);
   }
 

tests/image-stream/utils.spec.js

@@ -61,10 +61,10 @@ describe('ImageStream: Utils', function() {
       });
     });
 
-    it('should resolve application/octet-stream for an uncompressed iso', function() {
+    it('should resolve application/x-iso9660-image for an uncompressed iso', function() {
       const file = path.join(DATA_PATH, 'images', 'raspberrypi.iso');
       return utils.getArchiveMimeType(file).then((type) => {
-        m.chai.expect(type).to.equal('application/octet-stream');
+        m.chai.expect(type).to.equal('application/x-iso9660-image');
       });
     });
 
@@ -82,6 +82,13 @@ describe('ImageStream: Utils', function() {
       });
     });
 
+    it('should resolve application/octet-stream for an unrecognized file type', function() {
+      const file = path.join(DATA_PATH, 'unrecognized', 'random.rpi-sdcard');
+      return utils.getArchiveMimeType(file).then((type) => {
+        m.chai.expect(type).to.equal('application/octet-stream');
+      });
+    });
+
   });
 
   describe('.extractStream()', function() {