How to target sibling class element in javascript

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Javascript

CSS

HTML

CSS3

suppose you have HTML DOM like this

<div class="test1">
       <div class="test2">
       </div>
       <div class="test3">
       </div>
</div>

<div class="test1">
       <div class="test2">
       </div>
       <div class="test3">
       </div>
</div>

on click of test 2 i want test 3 to be displayed else display none;

What I have tried:

i tried to use this but that can be applied only if same class is applied to both the sibling