Some of the unit tests are too slow

Currently it takes ~40s to run the test suite. It used to be much faster, but we added a lot of unit tests since then and some of them are bottlenecks. We can use karma-time-stats-reporter plugin to discover which of the tests are slowing down the suite. Here’s the list of the slowest ones:

4707ms Map #flyTo move to requested center and zoom, and call zoomend once                                                           
2877ms Map #flyTo flyTo start latlng == end latlng                                                                                   
2862ms TileLayer number of kittens loaded Loads 290, unloads 275 kittens on MAD-TRD flyTo()                                          
2699ms GridLayer number of 256px tiles loaded in synchronous animated grid @800x600px Loads 290, unloads 275 tiles on MAD-TRD flyTo()
1329ms ImageOverlay #getCenter should open popup at the center                                                                       
808ms  Popup L.Map#openPopup moves the map over a long distance to the popup if it is not in the view (keepInView)                   
683ms  Map.ScrollWheelZoom changes the option 'wheelPxPerZoomLevel'                                                                  
612ms  Path #events can add a layer while being inside a moveend handler                                                             
358ms  Map.ScrollWheelZoom changes the option 'wheelDebounceTime'                                                                    
314ms  LineUtil #polylineCenter computes center of a small line and test it on every zoom                                            
309ms  Map.ScrollWheelZoom zooms out while firing 'wheel' event                                                                      
307ms  Map.Keyboard plus/minus keys zoom in                                                                                          
306ms  Map.ScrollWheelZoom scrollWheelZoom: 'center'                                                                                 
306ms  Map.Keyboard does not move the map if disabled no move north                                                                  
306ms  Map.Keyboard does not move the map if disabled no zoom in                                                                     
306ms  Map.Keyboard arrow keys move the map west                                                                                     
305ms  Map.Keyboard plus/minus keys zoom out                                                                                         
305ms  Map.Keyboard arrow keys move the map east                                                                                     
305ms  Map.Keyboard arrow keys move the map north                                                                                    
303ms  Map.Keyboard arrow keys move the map south                                                                                    
297ms  Map.ScrollWheelZoom zooms in while firing 'wheel' event                                                                       
266ms  Map #containerPointToLayerPoint return point relative to LayerPoint                                                           
263ms  Map.DoubleClickZoom doubleClickZoom: 'center'                                                                                 
260ms  Map.DoubleClickZoom zooms out while dblclick and holding shift                                                                
256ms  Map #layerPointToContainerPoint return point relative to ContainerPoint                                                       
252ms  TileLayer #setUrl fires only one load event                                                                                   
244ms  Map.DoubleClickZoom zooms in while dblclick                                                                                   
220ms  Control.Layers sortLayers keeps original order by default                                                                     
193ms  Map.Drag touch events reset itself after touchend                                                                             
191ms  Map.TouchZoom Dragging is possible after pinch zoom            

It would be nice to fix some of these if they don’t depend on such a long running length. Faster test suite means less friction when developing.

[rjackson]

I think this is all the savings I’ve found from all >100ms tests. The ones that remain I believe are bottlenecked by animation frames, as mentioned above.

Reductions so far:

Test	Before	After	Reduction
Popup L.Map#openPopup keepInView (speed up one test, add another 2)	812ms	802ms	10ms
Map.ScrollWheelZoomSpec	1881ms	332ms	1549ms
Map.DoubleClickZoomSpec	812ms	47ms	765ms
Path #events can add a layer while being inside a moveend handler	611ms	5ms	606ms
Map #layerPointToContainerPoint return point relative to ContainerPoint	269ms	1ms	268ms
Map #containerPointToLayerPoint return point relative to LayerPoint	258ms	1ms	257ms
TileLayer #setUrl fires only one load event	251ms	13ms	238ms
Marker #setIcon pan map to focus marker with no iconSize	103ms	1ms	102ms
Marker #setIcon pan map to focus marker	102ms	1ms	101ms
Total (sum of above)	5099ms	1204ms	3895ms

[rjackson]

A good chunk of our tests appear bottlenecked by the speed that Chrome running in headless mode will deliver animation frames. I’ve noticed this looking into tests using Leaflet/prosthetic-hand, as they seem to run twice as fast in a non-headless browser.

The tests overall do run a lot quicker in a windowed instance of Chrome. I suspect this is due to GPU acceleration.

npm run test -- --browsers Chrome

Test	Headless time	Headful time	Difference
Total time	11.465s	7.186s	1.59x
Net time	10.898s	6.763s	1.61x
Slowest tests
GridLayer number of 256px tiles loaded in synchronous animated grid @800x600px Loads 290, unloads 275 tiles on MAD-TRD flyTo()	2700ms	1349ms	2.00x
TileLayer number of kittens loaded Loads 290, unloads 275 kittens on MAD-TRD flyTo()	2678ms	1344ms	1.99x
Popup L.Map#openPopup moves on setLatLng after initial autopan	531ms	515ms	(same)
Map #setMaxBounds avoid subpixel / floating point related wobble	303ms	302ms	(same)
Popup L.Map#openPopup moves the map over a short distance to the popup if it is not in the view (keepInView)	267ms	257ms	(same)
Map #containerPointToLayerPoint return point relative to LayerPoint	253ms	254ms	(same)
Canvas #events does fire mousedown on layer after dragging map	198ms	81ms	2.44x
Map.TouchZoom Dragging is possible after pinch zoom	196ms	89ms	2.20x
Map.Drag touch events reset itself after touchend	195ms	97ms	2.01x
Map #flyTo flyTo start latlng == end latlng	115ms	108ms	(same)

I’m not sure if we want to do anything with this information. I don’t think it’s practical to run a windowed version of Chrome every time we run the tests, as the window popping up is quite disruptive. Nevertheless I wanted to document the finding 😃