title: setUp/tearDown (@Before/@After) why we need them in JUnit?
body: <p>I believe that we are all know that  setUp (@Before) will execute before any test method and tearDown(@After) will execute after test method.</p>
  
  <p>Also we know that Junit will create one instance of Test <strong>per test method</strong>. </p>
  
  <p>my question is that can we just move  setUp method content to class Constructor and remove setUp method? is there any specific reason to keep setUp method?</p>