either(...).or(...) broken for null values

[marksarnold]

Hello,

please take a look at the below test. I would expect all checks to succeed. However, the second and third do fail with:

java.lang.AssertionError: 
Expected: ("" or null)
     but: was null

The complete test code is this:

package zzz_small_tests;

import static org.hamcrest.CoreMatchers.equalTo;
import static org.hamcrest.CoreMatchers.nullValue;
import static org.hamcrest.core.CombinableMatcher.either;

import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ErrorCollector;

public class HamcrestEitherOrTest {
    @Rule
    public ErrorCollector collector= new ErrorCollector();


    @Test 
    public void testEitherOr() {
        String _s1 = "";
        collector.checkThat(_s1, either(equalTo("")).or(nullValue()));
        String _s2 = null;
        collector.checkThat(_s2, either(equalTo("")).or(nullValue()));
        collector.checkThat(_s2, either(equalTo("")).or(nullValue(String.class)));
    }
}

[UrsMetz]

I guess this addresses the situation as issue #49.

[marksarnold]

True. So I guess, the most sensible workaround for now would be using anyOf(equalTo(""), nullValue())...

If a fix can not be implemented in the next release, then at least the API doc of CombinableEitherMatcher and the respective either() and or() methods should warn about this!?

[StarBax89]

This is caused by this little pice of code in TypeSafeDiagnosingMatcher

@Override
    @SuppressWarnings("unchecked")
    public final boolean matches(Object item) {
        return item != null
            && expectedType.isInstance(item)
            && matchesSafely((T) item, new Description.NullDescription());
    }

The item != null and expectedType.isInstance(item) is false for item = null

This can be fixed by adding this dirty hack to CombinableMatcher

@Override
  public final boolean matches(Object item) {
    if(this.matcher instanceof AnyOf)
    {
      AnyOf anyOf = (AnyOf) this.matcher;
      List<Matcher<T>> matchers = (List<Matcher<T>>) anyOf.getMatchers();
      Boolean matches = false;
      for(Matcher eachMatcher : matchers)
      {
        if(eachMatcher.matches(item))
        {
          matches = true;
        }
      }
      return matches;
    }
    else {
      return super.matches(item);
    }
  }

Therefore TypeSafeDiagnosingMatcher's matches method must be non final and ShortcutCombination needs a getter for matchers.

I know this is really dirty, maybe someone can make a fix with this information. I'll also try to write a better fix for that.

EDIT: I also wrote a test private static final CombinableMatcher<String> EMPTY_STRING_OR_NULL = CombinableMatcher.either(equalTo("")).or(nullValue());

@Test public void
    acceptNullOrEmptyString() {
        assertMatches("or didn't pass", EMPTY_STRING_OR_NULL, null);
        assertMatches("either didn't pass", EMPTY_STRING_OR_NULL, "");
    }

[ScottG489]

Just ran into this issue. It's been 5 years after the initial report or even last comment so I wanted to bring attention to this again. Thank you for the workaround @marksarnold which I was able to use.

[Lms24]

I also ran into this issue today. Has there been any progress on this, given that the issue was raised 5 years ago?