refactor(image-stream): extract part of utils.js into mime.js (#1594)

This is a small refactoring commit that extracts the MIME related
function from utils.js into a new file called mime.js, and stores the
default image MIME type there as a constant, to avoid duplicating it in
multiple parts of the code.

Change-Type: patch
Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>

.gitattributes

@@ -39,3 +39,5 @@ Makefile text
 *.zip binary diff=hex
 *.dmg binary diff=hex
 *.rpi-sdcard binary diff=hex
+*.foo binary diff=hex
+xz-without-extension binary diff=hex

lib/image-stream/index.js

@@ -20,7 +20,7 @@ const _ = require('lodash');
 const Bluebird = require('bluebird');
 const fs = Bluebird.promisifyAll(require('fs'));
 const stream = require('stream');
-const utils = require('./utils');
+const mime = require('./mime');
 const handlers = require('./handlers');
 const supportedFileTypes = require('./supported');
 const errors = require('../shared/errors');
@@ -76,9 +76,8 @@ exports.getFromFilePath = (file) => {
       });
     }
 
-    return utils.getArchiveMimeType(file).then((type) => {
-      const MIME_TYPE_RAW_IMAGE = 'application/octet-stream';
-      const mimeType = _.has(handlers, type) ? type : MIME_TYPE_RAW_IMAGE;
+    return mime.getMimeTypeFromFileName(file).then((type) => {
+      const mimeType = _.has(handlers, type) ? type : mime.DEFAULT_MIME_TYPE;
       return _.invoke(handlers, mimeType, file, {
         size: fileStats.size
       });

lib/image-stream/mime.js

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2017 resin.io
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+'use strict';
+
+const _ = require('lodash');
+const Bluebird = require('bluebird');
+const fileType = require('file-type');
+const mime = require('mime-types');
+const fs = require('fs');
+
+/**
+ * @summary The default MIME type
+ * @type {String}
+ * @constant
+ */
+exports.DEFAULT_MIME_TYPE = 'application/octet-stream';
+
+/**
+ * @summary Get file's mime type, by reading the initial 262 bytes if necessary
+ * @function
+ * @public
+ *
+ * @param {String} filename - file path
+ * @fulfil {String} - mime type
+ * @returns {Promise}
+ *
+ * @example
+ * mime.getMimeTypeFromFileName('path/to/raspberrypi.img.gz').then((mimeType) => {
+ *   console.log(mimeType);
+ * });
+ */
+exports.getMimeTypeFromFileName = (filename) => {
+  const mimeType = mime.lookup(filename);
+
+  if (mimeType) {
+    return Bluebird.resolve(mimeType);
+  }
+
+  const FILE_TYPE_ID_BYTES = 262;
+
+  return Bluebird.using(fs.openAsync(filename, 'r').disposer((fileDescriptor) => {
+    return fs.closeAsync(fileDescriptor);
+  }), (fileDescriptor) => {
+    const BUFFER_START = 0;
+    const buffer = Buffer.alloc(FILE_TYPE_ID_BYTES);
+
+    return fs.readAsync(fileDescriptor, buffer, BUFFER_START, FILE_TYPE_ID_BYTES, null).then(() => {
+      return _.get(fileType(buffer), [ 'mime' ], exports.DEFAULT_MIME_TYPE);
+    });
+  });
+};

lib/image-stream/utils.js

@@ -16,48 +16,7 @@
 
 'use strict';
 
-const _ = require('lodash');
 const Bluebird = require('bluebird');
-const fileType = require('file-type');
-const mime = require('mime-types');
-const fs = require('fs');
-
-/**
- * @summary Get archive mime type
- * @function
- * @public
- *
- * @param {String} filename - file path
- * @fulfil {String} - mime type
- * @returns {Promise}
- *
- * @example
- * utils.getArchiveMimeType('path/to/raspberrypi.img.gz').then((mimeType) => {
- *   console.log(mimeType);
- * });
- */
-exports.getArchiveMimeType = (filename) => {
-  const MIME_TYPE_RAW_IMAGE = 'application/octet-stream';
-  const mimeType = mime.lookup(filename);
-
-  if (mimeType) {
-    return Bluebird.resolve(mimeType);
-  }
-
-  const FILE_TYPE_ID_BYTES = 262;
-
-  return Bluebird.using(fs.openAsync(filename, 'r').disposer((fileDescriptor) => {
-    return fs.closeAsync(fileDescriptor);
-  }), (fileDescriptor) => {
-    const BUFFER_START = 0;
-    const buffer = Buffer.alloc(FILE_TYPE_ID_BYTES);
-
-    return fs.readAsync(fileDescriptor, buffer, BUFFER_START, FILE_TYPE_ID_BYTES, null).then(() => {
-      return _.get(fileType(buffer), [ 'mime' ], MIME_TYPE_RAW_IMAGE);
-    });
-  });
-
-};
 
 /**
  * @summary Extract the data of a readable stream

tests/image-stream/mime.spec.js

@@ -0,0 +1,107 @@
+/*
+ * Copyright 2017 resin.io
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+'use strict';
+
+const m = require('mochainon');
+const path = require('path');
+const DATA_PATH = path.join(__dirname, 'data');
+const mime = require('../../lib/image-stream/mime');
+
+describe('ImageStream: MIME', function() {
+
+  describe('.getMimeTypeFromFileName()', function() {
+
+    it('should resolve application/x-bzip2 for a bz2 archive', function() {
+      const file = path.join(DATA_PATH, 'bz2', 'etcher-test.img.bz2');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/x-bzip2');
+      });
+    });
+
+    it('should resolve application/x-xz for a xz archive', function() {
+      const file = path.join(DATA_PATH, 'xz', 'etcher-test.img.xz');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/x-xz');
+      });
+    });
+
+    it('should resolve application/gzip for a gz archive', function() {
+      const file = path.join(DATA_PATH, 'gz', 'etcher-test.img.gz');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/gzip');
+      });
+    });
+
+    it('should resolve application/zip for a zip archive', function() {
+      const file = path.join(DATA_PATH, 'zip', 'zip-directory-etcher-only.zip');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/zip');
+      });
+    });
+
+    it('should resolve application/octet-stream for an uncompressed image', function() {
+      const file = path.join(DATA_PATH, 'images', 'etcher-test.img');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/octet-stream');
+      });
+    });
+
+    it('should resolve application/x-iso9660-image for an uncompressed iso', function() {
+      const file = path.join(DATA_PATH, 'images', 'etcher-test.iso');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/x-iso9660-image');
+      });
+    });
+
+    it('should resolve application/x-apple-diskimage for a compressed Apple disk image', function() {
+      const file = path.join(DATA_PATH, 'dmg', 'etcher-test-zlib.dmg');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/x-apple-diskimage');
+      });
+    });
+
+    it('should resolve application/x-apple-diskimage for an uncompressed Apple disk image', function() {
+      const file = path.join(DATA_PATH, 'dmg', 'etcher-test-raw.dmg');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/x-apple-diskimage');
+      });
+    });
+
+    it('should resolve application/octet-stream for an unrecognized file type', function() {
+      const file = path.join(DATA_PATH, 'unrecognized', 'random.rpi-sdcard');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/octet-stream');
+      });
+    });
+
+    it('should resolve the correct MIME type given an invalid extension', function() {
+      const file = path.join(DATA_PATH, 'unrecognized', 'xz-with-invalid-extension.foo');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/x-xz');
+      });
+    });
+
+    it('should resolve the correct MIME type given no extension', function() {
+      const file = path.join(DATA_PATH, 'unrecognized', 'xz-without-extension');
+      return mime.getMimeTypeFromFileName(file).then((type) => {
+        m.chai.expect(type).to.equal('application/x-xz');
+      });
+    });
+
+  });
+
+});

tests/image-stream/utils.spec.js

@@ -17,80 +17,11 @@
 'use strict';
 
 const m = require('mochainon');
-const path = require('path');
 const StreamReadable = require('stream').Readable;
-const DATA_PATH = path.join(__dirname, 'data');
 const utils = require('../../lib/image-stream/utils');
 
 describe('ImageStream: Utils', function() {
 
-  describe('.getArchiveMimeType()', function() {
-
-    it('should resolve application/x-bzip2 for a bz2 archive', function() {
-      const file = path.join(DATA_PATH, 'bz2', 'etcher-test.img.bz2');
-      return utils.getArchiveMimeType(file).then((type) => {
-        m.chai.expect(type).to.equal('application/x-bzip2');
-      });
-    });
-
-    it('should resolve application/x-xz for a xz archive', function() {
-      const file = path.join(DATA_PATH, 'xz', 'etcher-test.img.xz');
-      return utils.getArchiveMimeType(file).then((type) => {
-        m.chai.expect(type).to.equal('application/x-xz');
-      });
-    });
-
-    it('should resolve application/gzip for a gz archive', function() {
-      const file = path.join(DATA_PATH, 'gz', 'etcher-test.img.gz');
-      return utils.getArchiveMimeType(file).then((type) => {
-        m.chai.expect(type).to.equal('application/gzip');
-      });
-    });
-
-    it('should resolve application/zip for a zip archive', function() {
-      const file = path.join(DATA_PATH, 'zip', 'zip-directory-etcher-only.zip');
-      return utils.getArchiveMimeType(file).then((type) => {
-        m.chai.expect(type).to.equal('application/zip');
-      });
-    });
-
-    it('should resolve application/octet-stream for an uncompressed image', function() {
-      const file = path.join(DATA_PATH, 'images', 'etcher-test.img');
-      return utils.getArchiveMimeType(file).then((type) => {
-        m.chai.expect(type).to.equal('application/octet-stream');
-      });
-    });
-
-    it('should resolve application/x-iso9660-image for an uncompressed iso', function() {
-      const file = path.join(DATA_PATH, 'images', 'etcher-test.iso');
-      return utils.getArchiveMimeType(file).then((type) => {
-        m.chai.expect(type).to.equal('application/x-iso9660-image');
-      });
-    });
-
-    it('should resolve application/x-apple-diskimage for a compressed Apple disk image', function() {
-      const file = path.join(DATA_PATH, 'dmg', 'etcher-test-zlib.dmg');
-      return utils.getArchiveMimeType(file).then((type) => {
-        m.chai.expect(type).to.equal('application/x-apple-diskimage');
-      });
-    });
-
-    it('should resolve application/x-apple-diskimage for an uncompressed Apple disk image', function() {
-      const file = path.join(DATA_PATH, 'dmg', 'etcher-test-raw.dmg');
-      return utils.getArchiveMimeType(file).then((type) => {
-        m.chai.expect(type).to.equal('application/x-apple-diskimage');
-      });
-    });
-
-    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() {
 
     describe('given a stream that emits data', function() {