### Question:
Datapoint { public String toString() { return "X=" + mX + ", Y=" + mY; } Datapoint();  Datapoint(long x, long y); String toString(); public long mX; public long mY; }### Answer:
@Test public void toStringReturnsValue() throws Exception { Datapoint p1 = new Datapoint(); Datapoint p2 = new Datapoint(12, 45); String s1 = p1.toString(); String s2 = p2.toString(); assertTrue(p1.mX == 0); assertTrue(p1.mY == 0); assertTrue(s1.equals("X=" + p1.mX + ", Y=" + p1.mY)); assertTrue(s2.equals("X=" + p2.mX + ", Y=" + p2.mY)); }