[BUGFIX release] QP's bug for intermediate transitions

[rreckonerr]

Information

This is to make sure that emberjs/router.js#308 covers bug that resulted in missing query params in certain scenarios. Since there's a bunch of issues related to this bug we should write and combine failing tests together in this PR and land them after emberjs/router.js#308 is released.

Related issues

• Bug: updating one query param causes the other QP to reset to its default value #14438
• Failing test to demonstrate query params bug #16986
• Sticky query params broken with loading substate #12107
• Dynamic Segments / Query Params / Loading State Produces error with cacheValuePrefix #11857

TODOs

• Tests for link-to component (rebased Failing test to demonstrate query params bug #16986)
• Tests for for Bug: updating one query param causes the other QP to reset to its default value #14438
• Upgrade router.js

[rwjblue]

Great work, thanks for working through this!

[rreckonerr]

My pleasure :)

[sly7-7]

@rwjblue The tests are not enough here, and unfortunately, there is still a bug somewhere, but I think it's hard to reproduce in tests. I've investigated a bit, and found that during an intermediate transition (at least when I have an explicit loading template), although the url is still with the correct qp values, the controller properties of these qps are reset to their default values, and thus update the (parent) template. When the 'loading' transition is over, then the qps are back to their expected 'updated' values, and the templates update accordingly.

As a workaround, I've removed the loading template, and used a loading action to manually manage a loading flag in the parent controller, and conditionnaly display either the {{outlet}} or a loading component.