package org.junit.tests.experimental.theories.runner;
   
   import static org.hamcrest.CoreMatchers.containsString;
   import static org.hamcrest.CoreMatchers.everyItem;
   import static org.hamcrest.CoreMatchers.is;
   import static org.hamcrest.CoreMatchers.not;
   import static org.hamcrest.CoreMatchers.nullValue;
   import static org.junit.Assert.assertThat;
   import static org.junit.experimental.results.PrintableResult.testResult;
  import static org.junit.experimental.results.ResultMatchers.isSuccessful;
  import static org.junit.tests.experimental.theories.TheoryTestUtils.potentialAssignments;
  
  import java.util.ArrayList;
  import java.util.Date;
  import java.util.List;
  
  import org.hamcrest.Matcher;
  import org.junit.Test;
  import org.junit.experimental.theories.DataPoint;
  import org.junit.experimental.theories.Theories;
  import org.junit.experimental.theories.Theory;
  import org.junit.runner.JUnitCore;
  import org.junit.runner.RunWith;
  import org.junit.runner.notification.Failure;
  
  public class WithDataPointMethod {
      @RunWith(Theories.class)
      public static class HasDataPointMethod {
          @DataPoint
          public static int oneHundred() {
              return 100;
          }
  
          @Theory
          public void allIntsOk(int x) {
          }
      }
  
      @Test
      public void pickUpDataPointMethods() {
          assertThat(testResult(HasDataPointMethod.class), isSuccessful());
      }
  
      @RunWith(Theories.class)
      public static class DataPointMethodReturnsMutableObject {
          @DataPoint
          public static List<Object> empty() {
              return new ArrayList<Object>();
          }
  
          @DataPoint
          public static int ONE = 1;
  
          @DataPoint
          public static int TWO = 2;
  
          @Theory
          public void everythingsEmpty(List<Object> first, int number) {
              assertThat(first.size(), is(0));
              first.add("a");
          }
      }
  
      @Test
      public void mutableObjectsAreCreatedAfresh() {
          assertThat(failures(DataPointMethodReturnsMutableObject.class), empty());
      }
  
      @RunWith(Theories.class)
      public static class HasDateMethod {
          @DataPoint
          public static int oneHundred() {
              return 100;
          }
  
          public static Date notADataPoint() {
              return new Date();
          }
  
          @Theory
          public void allIntsOk(int x) {
          }
  
          @Theory
          public void onlyStringsOk(String s) {
          }
  
          @Theory
          public void onlyDatesOk(Date d) {
          }
      }
  
      @Test
      public void ignoreDataPointMethodsWithWrongTypes() throws Throwable {
          assertThat(potentialAssignments(
                  HasDateMethod.class.getMethod("onlyStringsOk", String.class))
                  .toString(), not(containsString("100")));
      }
  
     @Test
     public void ignoreDataPointMethodsWithoutAnnotation() throws Throwable {
         assertThat(potentialAssignments(
                 HasDateMethod.class.getMethod("onlyDatesOk", Date.class))
                 .size(), is(0));
     }
 
     private List<Failure> failures(Class<?> type) {
         return JUnitCore.runClasses(type).getFailures();
     }
 
     private Matcher<Iterable<Failure>> empty() {
         return everyItem(nullValue(Failure.class));
     }
 }