Issue148 - 0 children regression in dash==0.40.0

CHANGELOG.md

@@ -2,6 +2,10 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
+## [Unreleased]
+### Fixed
+- Fix regression for `children=0` case [#148](https://github.com/plotly/dash-renderer/issues/148)
+
 ## [0.22.0] - 2019-04-10
 ### Added
 - Added support for clientside callbacks [#143](https://github.com/plotly/dash-renderer/pull/143)

src/TreeContainer.js

@@ -33,7 +33,7 @@ const createContainer = component => isSimpleComponent(component) ?
 
 class TreeContainer extends Component {
     getChildren(components) {
-        if (!components) {
+        if (isNil(components)) {
             return null;
         }
 

tests/test_render.py

@@ -104,7 +104,7 @@ def request_queue_assertions(
 
         if expected_length is not None:
             self.assertEqual(len(request_queue), expected_length)
-    
+
     def test_initial_state(self):
         app = Dash(__name__)
         app.layout = html.Div([
@@ -475,6 +475,32 @@ def test_initial_state(self):
 
         assert_clean_console(self)
 
+    def test_array_of_falsy_child(self):
+        app = Dash(__name__)
+        app.layout = html.Div(id='nully-wrapper', children=[0])
+
+        self.startServer(app)
+
+        self.wait_for_element_by_css_selector('#nully-wrapper')
+        wrapper = self.driver.find_element_by_id('nully-wrapper')
+
+        self.assertEqual(wrapper.get_attribute('innerHTML'), '0')
+
+        assert_clean_console(self)
+
+    def test_of_falsy_child(self):
+        app = Dash(__name__)
+        app.layout = html.Div(id='nully-wrapper', children=0)
+
+        self.startServer(app)
+
+        self.wait_for_element_by_css_selector('#nully-wrapper')
+        wrapper = self.driver.find_element_by_id('nully-wrapper')
+
+        self.assertEqual(wrapper.get_attribute('innerHTML'), '0')
+
+        assert_clean_console(self)
+
     def test_simple_callback(self):
         app = Dash(__name__)
         app.layout = html.Div([