use typeof to check for crypto rather than global. Fixes #185 (#221)

* use typeof to check for crypto rather than global.  Fixes #185

* fix test(s) for node v0.12

* tweak

lib/rng-browser.js

@@ -2,25 +2,23 @@
 // browser this is a little complicated due to unknown quality of Math.random()
 // and inconsistent support for the `crypto` API.  We do the best we can via
 // feature-detection
-var rng;
 
-var crypto = global.crypto || global.msCrypto; // for IE 11
-if (crypto && crypto.getRandomValues) {
+if (typeof(crypto) != 'undefined' && crypto.getRandomValues) {
   // WHATWG crypto RNG - http://wiki.whatwg.org/wiki/Crypto
   var rnds8 = new Uint8Array(16); // eslint-disable-line no-undef
-  rng = function whatwgRNG() {
+
+  module.exports = function whatwgRNG() {
     crypto.getRandomValues(rnds8);
     return rnds8;
   };
-}
-
-if (!rng) {
+} else {
   // Math.random()-based (RNG)
   //
   // If all else fails, use Math.random().  It's fast, but is of unspecified
   // quality.
   var rnds = new Array(16);
-  rng = function() {
+
+  module.exports = function mathRNG() {
     for (var i = 0, r; i < 16; i++) {
       if ((i & 0x03) === 0) r = Math.random() * 0x100000000;
       rnds[i] = r >>> ((i & 0x03) << 3) & 0xff;
@@ -29,5 +27,3 @@ if (!rng) {
     return rnds;
   };
 }
-
-module.exports = rng;

lib/rng.js

@@ -1,10 +1,8 @@
 // Unique ID creation requires a high quality random # generator.  In node.js
 // this is pretty straight-forward - we use the crypto API.
 
-var rb = require('crypto').randomBytes;
+var crypto = require('crypto');
 
-function rng() {
-  return rb(16);
-}
-
-module.exports = rng;
+module.exports = function nodeRNG() {
+  return crypto.randomBytes(16);
+};

test/test.js

@@ -46,6 +46,49 @@ function compare(name, ids) {
   });
 }
 
+test('nodeRNG', function() {
+  var rng = require('../lib/rng');
+  assert.equal(rng.name, 'nodeRNG');
+
+  var bytes = rng();
+  assert.equal(bytes.length, 16);
+
+  for (var i = 0; i < bytes.length; i++) {
+    assert.equal(typeof(bytes[i]), 'number');
+  }
+});
+
+test('mathRNG', function() {
+  var rng = require('../lib/rng-browser');
+  assert.equal(rng.name, 'mathRNG');
+
+  var bytes = rng();
+  assert.equal(bytes.length, 16);
+
+  for (var i = 0; i < bytes.length; i++) {
+    assert.equal(typeof(bytes[i]), 'number');
+  }
+});
+
+test('cryptoRNG', function() {
+  // We shim the web crypto API to trigger cryptoRNG code path in rng module,
+  // then unshim once we've required it
+  global.crypto = {
+    getRandomValues: function(arr) {
+      return randomFillSync(arr);
+    }
+  };
+  var rng = require('../lib/rng-browser');
+  delete global.crypto;
+
+  var bytes = rng();
+  assert.equal(bytes.length, 16);
+
+  for (var i = 0; i < bytes.length; i++) {
+    assert.equal(typeof(bytes[i]), 'number');
+  }
+});
+
 test('sha1 node', function() {
   var sha1 = require('../lib/sha1');