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// SPDX-License-Identifier: BUSL-1.1
pragma solidity ^0.8.13;

contract Fibonacci {
    /*
        This exercise assumes you understand what Fibonacci sequence is.
        1. Function `fibonacci` takes a uint256 as argument and returns nth fibonacci number.
        
        Fibonacci sequence are 0,1,1,2,3,5,8,13,....
        
        calling fibonacci(6) would return 8, because the 6th Fibonacci number is 8.
    */

    function fibonacci(uint256 _position) public view returns (uint256) {
        // your code here
    }
}

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    function fibonacci(uint256 _position) public view returns (uint256) {
        // your code here
        if (_position == 0) {
            return 0;
        }else if (_position == 1) {
            return 1;
        }else{
            return fibonacci(_position-1) + fibonacci(_position - 2);
        }
    }

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// SPDX-License-Identifier: BUSL-1.1
pragma solidity ^0.8.13;

import "forge-std/Test.sol";
import "../src/Fibonacci.sol";

contract FibonacciTest is Test {
    Fibonacci public fibonacci;

    function setUp() public {
        fibonacci = new Fibonacci();
    }

    function testFibonacci() external {
        uint256 result = fibonacci.fibonacci(4);
        uint256 result1 = fibonacci.fibonacci(10);
        uint256 result2 = fibonacci.fibonacci(20);
        uint256 result3 = fibonacci.fibonacci(1);

        assertEq(result, 3, "expected result to be 3");
        assertEq(result1, 55, "expected result to be 55");
        assertEq(result2, 6765, "expected result to be 6765");
        assertEq(result3, 1, "expected result to be 1");
    }
}