### Question:
Foo { public int foo(int n) { if (n > 0) { n--; } else { n++; } return n; }  int foo(int n);  }### Answer:
@Test public void test01() { assertEquals(9, new Foo().foo(10)); }
@Test public void test02() { assertEquals(99, new Foo().foo(100)); }
@Test public void test03() { assertEquals(0, new Foo().foo(0)); }
@Test public void test04() { assertEquals(-9, new Foo().foo(-10)); }