docs(core): provide note for unit test changes with the `ng-star-inse…

…rted` className (#21450)

PR Close #21450

CHANGELOG.md

@@ -9,6 +9,7 @@
 * **benchpress:** work around missing events from Chrome 63 ([#21396](https://github.com/angular/angular/issues/21396)) ([fa03ae1](https://github.com/angular/angular/commit/fa03ae1))
 * **common:** export currencies via `getCurrencySymbol` ([#20983](https://github.com/angular/angular/issues/20983)) ([fecf768](https://github.com/angular/angular/commit/fecf768))
 
+Note: Due to an animation fix back in 5.1.1 ([c2b3792](https://github.com/angular/angular/commit/c2b3792a3b5fa5215fe2ef7e0ac6511086ffe4c1)) which allows for nested :leave queries to work within animation sequences, all elements that are dynamically inserted (*ngIf, *ngFor, etc…) now contain the special CSS class: “ng-star-inserted”. This may cause failures within unit tests if there are any assertions that match against element.className directly. (An easy fix for this is to match using a regular expression instead of asserting the className string directly.)
 
 <a name="5.2.0-rc.0"></a>
 # [5.2.0-rc.0](https://github.com/angular/angular/compare/5.2.0-beta.1...5.2.0-rc.0) (2018-01-04)