### Question:
ParamChecker { public static <T> T notNull(T t, String paramName) { if (t == null) { throw new IllegalArgumentException(paramName + " cannot be NULL"); } return t; }  static T notNull(T t, String paramName); static String notEmpty(String s, String paramName); static List<T> notNulls(List<T> l, String paramName); static int greaterEqualZero(int i, String paramName); static int greaterThan(int i, int base, String paramName); static long greaterEqualZero(long i, String paramName); static long greaterThan(long i, long base, String paramName); static void asserts(boolean b, String msg);  }### Answer:
@Test public void testNotNullOK() { Object o = new Object(); Assert.assertSame(o, ParamChecker.notNull(o, "o")); }
@Test(expected = IllegalArgumentException.class) public void testNotNullFail() { ParamChecker.notNull(null, "o"); }
@Test public void testNotEmptyOK() { String s = "a"; Assert.assertSame(s, ParamChecker.notNull(s, "s")); }