Fix flow error when calling hash.digest()

Reviewed By: cpojer

Differential Revision: D6598742

fbshipit-source-id: 47bd6f0ee0d54c61c2ff9b201005e7366d9df76d

packages/metro/src/shared/output/__tests__/__snapshots__/meta-test.js.snap

@@ -0,0 +1,30 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`exports the blacklist creator 1`] = `
+Object {
+  "data": Array [
+    56,
+    131,
+    13,
+    89,
+    254,
+    63,
+    108,
+    210,
+    213,
+    112,
+    53,
+    173,
+    11,
+    21,
+    31,
+    184,
+    133,
+    221,
+    114,
+    86,
+    1,
+  ],
+  "type": "Buffer",
+}
+`;

packages/metro/src/shared/output/__tests__/meta-test.js

@@ -0,0 +1,18 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @format
+ * @emails oncall+js_foundation
+ */
+'use strict';
+
+const meta = require('../meta');
+
+it('exports the blacklist creator', () => {
+  expect(meta('some formatted code', 'utf8')).toMatchSnapshot();
+});

packages/metro/src/shared/output/meta.js

@@ -31,7 +31,7 @@ module.exports = function(
   const buffer: Buffer = asBuffer(code, encoding);
   const hash = crypto.createHash('sha1');
   hash.update(buffer);
-  const digest = hash.digest('buffer');
+  const digest = hash.digest();
   const signature = Buffer.alloc
     ? Buffer.alloc(digest.length + 1)
     : new Buffer(digest.length + 1);