Clear subplotType cache on Plotly.register()

src/plots/plots.js

@@ -579,8 +579,8 @@ function getTraceUids(oldFullData, newData) {
  * Single-trace subplots (which have no `id`) such as pie, table, etc
  * do not need to be collected because we just draw all visible traces.
  */
-var collectableSubplotTypes;
 function emptySubplotLists() {
+    var collectableSubplotTypes = Registry.collectableSubplotTypes;
     var out = {};
     var i, j;
 

src/registry.js

@@ -31,6 +31,7 @@ exports.layoutArrayRegexes = [];
 exports.traceLayoutAttributes = {};
 exports.localeRegistry = {};
 exports.apiMethodRegistry = {};
+exports.collectableSubplotTypes = null;
 
 /**
  * Top-level register routine, exported as Plotly.register
@@ -72,6 +73,8 @@ exports.apiMethodRegistry = {};
  *
  */
 exports.register = function register(_modules) {
+    exports.collectableSubplotTypes = null;
+
     if(!_modules) {
         throw new Error('No argument passed to Plotly.register.');
     } else if(_modules && !Array.isArray(_modules)) {

test/jasmine/bundle_tests/dynamic_import_test.js

@@ -0,0 +1,40 @@
+var Plotly = require('@lib/core');
+
+var d3 = require('d3');
+var createGraphDiv = require('../assets/create_graph_div');
+var destroyGraphDiv = require('../assets/destroy_graph_div');
+var failTest = require('../assets/fail_test');
+
+describe('Dynamic @lib/ module imports', function() {
+    var gd;
+
+    afterEach(destroyGraphDiv);
+
+    it('should work', function(done) {
+        gd = createGraphDiv();
+
+        Plotly.newPlot(gd, [{
+            y: [1, 2, 1]
+        }])
+        .then(function() {
+            // N.B. from a different subplot type
+            // more info in:
+            // https://github.com/plotly/plotly.js/issues/3428
+            var ScatterPolar = require('@lib/scatterpolar');
+            Plotly.register(ScatterPolar);
+        })
+        .then(function() {
+            return Plotly.newPlot(gd, [{
+                type: 'scatterpolar',
+                r: [1, 2, 1]
+            }]);
+        })
+        .then(function() {
+            var polarLayer = d3.select('.polarlayer');
+            expect(polarLayer.size()).toBe(1, 'one polar layer');
+            expect(polarLayer.selectAll('.trace').size()).toBe(1, 'one scatterpolar trace');
+        })
+        .catch(failTest)
+        .then(done);
+    });
+});