title: Testing API which returns multiple values with JUnit
body: <p>I would like to test an API, which received one argument and returns a set. The test  invokes the API with an argument and checks if the returned set contains expected values.</p>
  
  <p>Suppose, I have to test the API with arguments <code>arg1</code>, <code>arg2</code>, and <code>arg3</code> and check if values <code>a</code>, <code>b</code>, <code>c</code> appear in the returned set. That is, my test case looks as follows:</p>
  
  <ul>
  <li>invoke the API with <code>arg1</code> and check if <code>a</code>,
  <code>b</code>, <code>c</code> appear in the returned set.</li>
  <li>invoke the API with <code>arg2</code> and check if <code>a</code>,
  <code>b</code>, <code>c</code> appear in the returned set.</li>
  <li>invoke the API with <code>arg3</code> and check if <code>a</code>,
  <code>b</code>, <code>c</code> appear in the returned set.</li>
  </ul>
  
  <p>How to develop this test case with <code>Junit 4</code> ? What if I have to add <code>arg4</code> ? What if I have to check if value <code>d</code> appear in the returned set ? Can I read the list of arguments and expected values from the configuration? </p>