Add in tests for non-native dataview

This includes a new module that will run about 1 out of every 3
runs that will make sure the browser DataView is replaced with an
object. Without the updates to supportsDataView this would fail
since stringTagBug would try to call the constructor on it.

karma.conf-sauce.js

@@ -63,6 +63,7 @@ module.exports = function(config) {
     files: [
       'test/vendor/qunit-extras.js',
       'test/qunit-setup.js',
+      'test/overrides.js',
       'underscore-umd.js',
       'test/*.js'
     ],

karma.conf.js

@@ -15,6 +15,7 @@ module.exports = function(config) {
     // list of files / patterns to load in the browser
     files: [
       'test/qunit-setup.js',
+      'test/overrides.js',
       'underscore-umd.js',
       'test/*.js'
     ],

test/index.html

@@ -9,6 +9,7 @@
   <div id="qunit"></div>
   <div id="exports" style="display: none"></div>
   <script src="vendor/qunit.js"></script>
+  <script src="overrides.js"></script>
   <script src="../underscore-umd.js"></script>
   <script src="qunit-setup.js"></script>
   <script src="collections.js"></script>

test/objects.js

@@ -609,12 +609,12 @@
       var view2 = new Uint8Array(shared.buffer, 2, 2);
       assert.notOk(_.isEqual(view1, view2), 'same buffer with different offset is not equal');
 
-      // Some older browsers support typed arrays but not DataView.
-      if (typeof DataView !== 'undefined') {
-        assert.ok(_.isEqual(new DataView(u8.buffer), new DataView(u8b.buffer)), 'Identical DataViews are equal');
-        assert.ok(_.isEqual(new DataView(u8.buffer), new DataView(i8.buffer)), 'Identical DataViews of different typed arrays are equal');
-        assert.notOk(_.isEqual(new DataView(u8.buffer), new DataView(u16.buffer)), 'Different DataViews with different length are not equal');
-        assert.notOk(_.isEqual(new DataView(u8.buffer), new DataView(u16one.buffer)), 'Different DataViews with different byte data are not equal');
+      var DataViewImpl = typeof NativeDataView !== 'undefined' ? NativeDataView : typeof DataView !== 'undefined' ? DataView : undefined; // Browser could override DataView
+      if (DataViewImpl) {
+        assert.ok(_.isEqual(new DataViewImpl(u8.buffer), new DataViewImpl(u8b.buffer)), 'Identical DataViews are equal');
+        assert.ok(_.isEqual(new DataViewImpl(u8.buffer), new DataViewImpl(i8.buffer)), 'Identical DataViews of different typed arrays are equal');
+        assert.notOk(_.isEqual(new DataViewImpl(u8.buffer), new DataViewImpl(u16.buffer)), 'Different DataViews with different length are not equal');
+        assert.notOk(_.isEqual(new DataViewImpl(u8.buffer), new DataViewImpl(u16one.buffer)), 'Different DataViews with different byte data are not equal');
       }
     }
   });
@@ -930,9 +930,9 @@
         'an ArrayBuffer': buffer,
         'a TypedArray': new Uint8Array(buffer)
       };
-      // Some older browsers support typed arrays but not DataView.
-      if (typeof DataView !== 'undefined') {
-        checkValues['a DataView'] = new DataView(buffer);
+      var DataViewImpl = typeof NativeDataView !== 'undefined' ? NativeDataView : typeof DataView !== 'undefined' ? DataView : undefined; // Browser could override DataView
+      if (DataViewImpl) {
+        checkValues['a DataView'] = new DataViewImpl(buffer);
       }
       var types = ['an ArrayBuffer', 'a DataView', 'a TypedArray'];
       _.each(types, function(type) {

test/overrides.js

@@ -0,0 +1,11 @@
+(function() {
+  function overrideDataView() {
+    NativeDataView = DataView;
+    DataView = {};
+  }
+
+  var runOverrides = Math.floor(Math.random() * 3) === 0;
+  if (runOverrides) { // Only override browser functions roughly 1/3rd of the time
+    overrideDataView();
+  }
+})();