[fix][test] Fix flaky IsolatedBookieEnsemblePlacementPolicyTest.testBookieInfoChange

[merlimat]

Motivation

IsolatedBookieEnsemblePlacementPolicyTest.testBookieInfoChange is flaky because initialize() loads the bookie rack configuration asynchronously. When newEnsemble() runs before the async load completes, cachedRackConfiguration is null, no bookie isolation is applied, and the ensemble may include bookies from the wrong group.

Stack trace

IsolatedBookieEnsemblePlacementPolicyTest > testBookieInfoChange FAILED
    java.lang.AssertionError: expected [true] but found [false]
        at org.testng.Assert.fail(Assert.java:110)
        at org.testng.Assert.failNotEquals(Assert.java:1577)
        at org.testng.Assert.assertTrue(Assert.java:56)
        at org.testng.Assert.assertTrue(Assert.java:66)
        at IsolatedBookieEnsemblePlacementPolicyTest.testBookieInfoChange(IsolatedBookieEnsemblePlacementPolicyTest.java:390)

Modifications

Add an Awaitility wait after initialize() to ensure the async cache load has completed before calling newEnsemble().

Documentation

• doc-not-needed