content: package com._17od.upm.util;
  
  import junit.framework.TestCase;
  
  public class ValidatorTest extends TestCase {
  
      private static final String errorMsg = "There is a problem with the provided argument";
      
      public void testTrueConditionDoesntThrowError() {
          Validator.checkArgument(5 > 2, errorMsg);
      }
      
      public void testFalseConditionThrowsError() {
          try {
              Validator.checkArgument(-1 > 2, errorMsg);
              fail("No error was thrown, but expected IllegalArg");
          } catch (IllegalArgumentException e) {
              // Do nothing, it was thrown as expected
          }
      }
      
      public void testNonNullDoesntThrowError() {
          Validator.checkNotNull("I'm not null", errorMsg);
      }
      
      public void testNullThrowsError() {
          try {
              Validator.checkNotNull(null, errorMsg);
              fail("No error was thrown, but expected IllegalArg");
          } catch (IllegalArgumentException e) {
              // Do nothing, it was thrown as expected
          }
      }
  }
  