different
        // lengths.  We want to report this only after we've already
        // checked the main tree for equality, though, so it doesn't
        // mask more interesting errors.
        assert_equals(actualRoots.length, expectedRoots.length,
          "Actual and expected DOMs were broken up into a different number of pieces by cloneContents() (this probably means you created or detached nodes when you weren't supposed to)");
      }
    }
  });
  domTests[i].done();

  positionTests[i].step(func