Using hamcrest to assert that I get a collection of Objects back and that one of them has a property set to a particular value?

Question

I just started using Hamcrest, so I'm probably doing it all wrong.

I have a List<Foo> foos and the Foo interface looks a bit like this:

public abstract interface Foo {

  public String getBar();

}

It is implemented by impl.FooImpl:

public class FooImpl implements Foo {

  protected String _bar = "some value";

  public String getBar() {
    return _bar;
  }

}

My assert looks like this:

assertThat(
  foos, 
  Matchers.hasItem(
    Matchers.<Foo> hasProperty(
      "bar", 
      equalTo("some value")
    )
  )
);

Unfortunately, JUnit/Hamcrest isn't happy:

java.lang.AssertionError: 
Expected: a collection containing hasProperty("bar", "someValue")
     got: <[com.example.impl.FooImpl@2c78bc3b]>

Any idea what I need to do to fix this?

Update: My "test" class is here:

public class FooTest {
  public static void main(String... args) throws Exception {
    List<Foo> foos = Arrays.<Foo> asList(new FooImpl());
      assertThat(
        foos, 
        Matchers.<FooImpl> hasItem(Matchers.hasProperty("bar", equalTo("some value")))
      );
  }
}

Clearly, what I'd like to see is that assert pass without getting an exception... :)

Update: this is now fixed; I just set up a blank maven project in IntelliJ and it ran fine. It might have been down to a typo, or me importing the wrong method in Eclipse, but it's a OSI Layer 8 problem for sure. I asked for the conversation to be closed. Sorry everyone, and thanks for your help.

Answer 1

The code you posted works fine. The error you have is due to a mismatch between "someValue" and "some value" in the code you're running locally. Upgrade to Hamcrest 1.3 and you'll get a clearer error message:

Expected: a collection containing hasProperty("bar", "someValue")
    but: property 'bar' was 'some value'

Since you may be getting different results, here's a full example that passes, with JUnit 4.11 and Hamcrest 1.3. In Foo.java:

public class Foo {
    public String getBar() {
        return "some value";
    }
}

And in FooTest.java:

import static org.junit.Assert.assertThat;

import java.util.Arrays;
import java.util.List;

import org.hamcrest.Matchers;
import org.junit.Test;

public class FooTest {
    @Test
    public void test() {
        List<Foo> foos = Arrays.asList(new Foo());

        assertThat(foos,
                Matchers.<Foo>hasItem(Matchers.hasProperty("bar", Matchers.equalTo("some value"))));
    }
}

If I intentionally break this test by changing the property name in the test to "notbar" then I get:

java.lang.AssertionError: 
Expected: a collection containing hasProperty("notbar", "some value")
     but: No property "notbar"

If, instead, I break it by expecting "some other value", then I get:

java.lang.AssertionError: 
Expected: a collection containing hasProperty("bar", "some other value")
     but: property 'bar' was "some value"

If you're getting different, or less clear, errors, you may have a separate issue.