### Question:
Index { @Override public int hashCode() { return 17 * row + 37 * column; } Index();  Index(int row, int column); int getRow(); int getColumn(); boolean isDiagonal(); @Override int hashCode(); @Override boolean equals(Object other); @Override String toString();  }### Answer:
@Test public void testEquality() { Index a = new Index(0, 12); Index b = new Index(0, 12); assertEquals(a.hashCode(), b.hashCode()); assertEquals(a, b); }