HierarchyNode implements Serializable { public boolean containsDependency(File dependency) { Validate.notNull(dependency, "Dependency can't be null"); return dependencies.contains(new File(dependency)); } HierarchyNode(File file, HierarchyNode parent); void addDependency(HierarchyNode node); void addMissingDependency(String name); boolean hasDependencies(); File getFile(); Set<File> getDependencies(); Set<String> getMissingDependencies(); boolean containsDependency(File dependency); @Override int hashCode(); @Override boolean equals(Object obj); @Override String toString();  }
@Test(expected = IllegalArgumentException.class) public void containsDependency() { root.containsDependency(null); }