package org.junit.tests;
   
   import static org.hamcrest.CoreMatchers.is;
   import static org.junit.Assert.assertThat;
   import static org.junit.Assume.assumeNotNull;
   import static org.junit.Assume.assumeThat;
   
   import java.lang.reflect.Method;
   
  import org.junit.Test;
  import org.junit.Test.None;
  import org.junit.experimental.theories.DataPoints;
  import org.junit.experimental.theories.Theories;
  import org.junit.experimental.theories.Theory;
  import org.junit.runner.RunWith;
  import org.junit.runners.model.FrameworkMethod;
  
  @RunWith(Theories.class)
  public class ObjectContractTest {
      @DataPoints
      public static Object[] objects = {new FrameworkMethod(toStringMethod()),
              new FrameworkMethod(toStringMethod()), 3, null};
  
      @Theory
      @Test(expected = None.class)
      public void equalsThrowsNoException(Object a, Object b) {
          assumeNotNull(a);
          a.equals(b);
      }
  
      @Theory
      public void equalsMeansEqualHashCodes(Object a, Object b) {
          assumeNotNull(a, b);
          assumeThat(a, is(b));
          assertThat(a.hashCode(), is(b.hashCode()));
      }
  
      private static Method toStringMethod() {
          try {
              return Object.class.getMethod("toString");
          } catch (SecurityException e) {
          } catch (NoSuchMethodException e) {
          }
          return null;
      }
  }