@Test public void testSum() { assertEquals(5, calculator.sum(2, 3)); }
int sum(int a, int b) { return a + b; }
Calculator { int sum(int a, int b) { return a + b; } }
Calculator { int sum(int a, int b) { return a + b; }  }
Calculator { int sum(int a, int b) { return a + b; }   }
Calculator { int sum(int a, int b) { return a + b; }    }