import junit.framework.TestCase;

public class FibonacciTest extends TestCase {

    private long fib(final int index) {
        final long[] prevTwo = previousTwoFibonacciNumbers(index);
        assertEquals(2, prevTwo.length);
        return prevTwo[0] + prevTwo[1];
    }

    private long[] previousTwoFibonacciNumbers(final int index) {
        switch (index) {
            case 0:
                return new long[]{0, 0};
            case 1:
            case 2:
                return new long[]{0, 1};
            default:
                final long[] prevTwo = previousTwoFibonacciNumbers(index - 1);
                return new long[]{prevTwo[1], prevTwo[0] + prevTwo[1]};
        }
    }

    public void test0() {
        assertEquals(0, fib(0));
    }

    public void test1() {
        assertEquals(1, fib(1));
    }

    public void test2() {
        assertEquals(1, fib(2));
    }

    public void test3() {
        assertEquals(2, fib(3));
    }

    public void test4() {
        assertEquals(3, fib(4));
    }

    public void test5() {
        assertEquals(5, fib(5));
    }

    public void test6() {
        assertEquals(8, fib(6));
    }

    public void testX() {
        final long[] values = new long[]{
                0L,
                1L,
                1L,
                2L,
                3L,
                5L,
                8L,
                13L,
                21L,
                34L,
                55L,
                89L,
                144L,
                233L,
                377L,
                610L,
                987L,
                1597L,
                2584L,
                4181L,
                6765L,
                10946L,
                17711L,
                28657L,
                46368L,
                75025L,
                121393L,
                196418L,
                317811L,
                514229L,
                832040L,
                1346269L,
                2178309L,
                3524578L,
                5702887L,
                9227465L,
                14930352L,
                24157817L,
                39088169L,
                63245986L,
                102334155L,
                165580141L,
                267914296L,
                433494437L,
                701408733L,
                1134903170L,
                1836311903L,
                2971215073L,
                4807526976L,
                7778742049L,
                12586269025L,
                20365011074L,
                32951280099L,
                53316291173L,
                86267571272L,
                139583862445L,
                225851433717L,
                365435296162L,
                591286729879L,
                956722026041L,
                1548008755920L,
                2504730781961L,
                4052739537881L,
                6557470319842L,
                10610209857723L,
                17167680177565L,
                27777890035288L,
                44945570212853L,
                72723460248141L,
                117669030460994L,
                190392490709135L,
                308061521170129L,
                498454011879264L,
                806515533049393L,
                1304969544928657L,
                2111485077978050L,
                3416454622906707L,
                5527939700884757L,
                8944394323791464L,
                14472334024676221L,
                23416728348467685L,
                37889062373143906L,
                61305790721611591L,
                99194853094755497L,
                160500643816367088L,
                259695496911122585L,
                420196140727489673L,
                679891637638612258L,
                1100087778366101931L,
                1779979416004714189L,
                2880067194370816120L,
                4660046610375530309L,
                7540113804746346429L
        };
        int index = 0;
        for (long value : values) {
            assertEquals("fib(" + index + ")", value, fib(index));
            ++index;
        }
    }

}