public virtual void test_andThen()
        {
            ObjDoubleFunction <int, string> fn1 = (a, b) => a + "=" + b;
            ObjDoubleFunction <int, string> fn2 = fn1.andThen(str => "[" + str + "]");

            assertEquals(fn1.apply(2, 3.2d), "2=3.2");
            assertEquals(fn2.apply(2, 3.2d), "[2=3.2]");
        }
//JAVA TO C# CONVERTER TODO TASK: Most Java annotations will not have direct .NET equivalent attributes:
//ORIGINAL LINE: @Test(expectedExceptions = NullPointerException.class) public void test_andThen_null()
        public virtual void test_andThen_null()
        {
            ObjDoubleFunction <int, string> fn1 = (a, b) => a + "=" + b;

            fn1.andThen(null);
        }