add e2e tests

Author: iamzili

vertical-pod-autoscaler/enhancements/8515-support-custom-request-to-limit-ratio/README.md

@@ -19,6 +19,7 @@
       - [When Disabled](#when-disabled)
     - [Kubernetes Version Compatibility](#kubernetes-version-compatibility)
     - [Test Plan](#test-plan)
+      - [E2E](#e2e)
     - [Examples](#examples)
   - [Implementation History](#implementation-history)
 <!-- /toc -->
@@ -154,8 +155,13 @@ The behavior after implementing this feature is as follows:
 ### Test Plan
 
 * Implement comprehensive unit tests to cover all new functionality.  
-* e2e tests: TODO
 
+#### E2E
+
+* e2e tests with `InPlaceOrRecreate` VPA mode:
+  1. Add a test case where the QoS class **changes**. In this scenario, we expect the updater to evict the affected Pods, since the QoS field is immutable.
+  2. Add a test case where the QoS class **does not change**. In this scenario the updater should apply the new ratio using the in-place update mechanism.
+* Add a test case to verify that when `RequestToLimitRatio` is specified for a container, the ratio from the Workload API (i.e. Deployment) is ignored and no longer considered.
 
 ### Examples