### Question:
Columns implements Iterable<Column> { public boolean contains(Column column) { return ArrayUtils.contains(columns, column); } Columns(Column... columns);  Columns(Collection<Column> columns); boolean contains(Column column); boolean contains(Columns columns); Iterator<Column> iterator(); int count(); String namesJoint(String separator); String namesJoint(String template, String separator); Columns exclude(Columns toexclude); @Override int hashCode(); @Override boolean equals(Object obj); @Override String toString();  }### Answer:
@Test public void contains_returnsTrue() { Columns columns = new Columns(NAME, BIRTH_DATE); assertTrue(columns.contains(NAME)); assertTrue(columns.contains(new Columns(NAME, BIRTH_DATE))); }
@Test public void contains_returnsFalse() { Columns columns = new Columns(NAME); assertFalse(columns.contains(BIRTH_DATE)); assertFalse(columns.contains(new Columns( new Column("unexistant", Column.Type.BOOLEAN), new Column("unexistant2", Column.Type.DATETIME)))); }