Failing test for issue with controllerName + queryParams + transitionTo

[cafreeman]

When using the controllerName property to share a controller across a parent and child route, RouterService#transitionTo fails when attempting to transition to the route that that is "sharing" via controllerName.

For example, parent has a controller that defines queryParams as ['foo'], and parent.child uses controllerName: 'parent' to share the controller. Attempting to call RouterService#transitionTo('parent.child') will throw the following error:

Assertion Failed: You passed the `parent:foo` query parameter during a transition into parent.child, please update to foo

Based on the digging I've done so far, I can tell you that this assertion is happening in router.js here, and appears to be failing due to parentProp being undefined.

There appears to be prior discussion/work on this issue, as seen in the following commits/issues:

• 1c8c6ec
• 3b9489c
• Ember 2.16 router service unable to transition without all query parameters present #15725

However, I haven't found anything related specifically to the controllerName issue, though the same assertion is being triggered in all cases.

Here is a twiddle that demonstrates the issue.

Fixes #14560.

[locks]

@cafreeman are you able to rebase this PR?

[cafreeman]

@locks just rebased

[btecu]

@cafreeman Is this no longer an issue?