### Question:
Columns implements Iterable<Column> { @Override public String toString() { return new StringBuilder(getClass().getSimpleName()) .append(Arrays.toString(columns)) .toString(); } 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 toString_returnsExpectedText() { assertEquals("MyColumns[name<T>, birth_date<D>]", new MyColumns().toString()); }