Merge pull request #2330 from mapbox/node-parallel-throw

[node] throw if a render is already pending, fixes #2247

platform/node/src/node_map.cpp

@@ -186,6 +186,10 @@ NAN_METHOD(NodeMap::Render) {
         return Nan::ThrowTypeError("Style is not loaded");
     }
 
+    if (nodeMap->callback) {
+        return Nan::ThrowError("Map is currently rendering an image");
+    }
+
     auto options = ParseOptions(info[0]->ToObject());
 
     assert(!nodeMap->callback);

platform/node/test/js/map.test.js

@@ -266,18 +266,14 @@ test('Map', function(t) {
             render();
         });
 
-        t.skip('throws if called in parallel', function(t) {
-            var completed = 0;
-            var remaining = 10;
-            var start = +new Date;
-
+        t.test('throws if called in parallel', function(t) {
             var map = new mbgl.Map(options);
             map.load(style);
 
             t.throws(function() {
                 map.render({}, function() {});
                 map.render({}, function() {});
-            });
+            }, /Map is currently rendering an image/);
 
             map.release();
             t.end();