I have the functional requirement to build an algorithm that takes any real number and gives back a tuple of the closest number in the Fibonacci sequence and the next one.

Please write me a couple of unit tests for this requirement using xunit and shouldly.
I can suggest the following unit tests using xunit and shouldly for the requirement you provided:

public class FibonacciTests
{
    [Fact]
    public void TestClosestFibonacciNumbers()
    {
        //Arrange
        int inputNumber = 31;
        int expectedFirstNumber = 21;
        int expectedSecondNumber = 34;

        //Act
        Tuple<int, int> result = Fibonacci.GetClosestFibonacciNumbers(inputNumber);

        //Assert
        result.Item1.ShouldBe(expectedFirstNumber);
        result.Item2.ShouldBe(expectedSecondNumber);
    }

    [Fact]
    public void TestInputIsFibonacci()
    {
        //Arrange
        int inputNumber = 55;
        int expectedFirstNumber = 55;
        int expectedSecondNumber = 89;

        //Act
        Tuple<int, int> result = Fibonacci.GetClosestFibonacciNumbers(inputNumber);

        //Assert
        result.Item1.ShouldBe(expectedFirstNumber);
        result.Item2.ShouldBe(expectedSecondNumber);
    }
}
In these tests, we are testing the functionality of the Fibonacci.GetClosestFibonacciNumbers() method.

The first test case verifies that the method returns the correct tuple of the closest number in the Fibonacci sequence and the next one for a given number.

The second test case verifies that the method returns the correct tuple for an input number that is already in the Fibonacci sequence.


here are some examples of unit tests that can be used to test the algorithm that takes any real number and gives back a tuple of the closest number in the Fibonacci sequence and the next one.

public class FibonacciSequenceTests
{
    private readonly FibonacciSequence _fibonacci;

    public FibonacciSequenceTests()
    {
        _fibonacci = new FibonacciSequence();
    }

    [Fact]
    public void GivenNumber0_ReturnsTupleOf1And1()
    {
        var result = _fibonacci.GetClosestFibonacci(0);

        result.Item1.ShouldBe(1);
        result.Item2.ShouldBe(1);
    }

    [Fact]
    public void GivenNumber6_ReturnsTupleOf5And8()
    {
        var result = _fibonacci.GetClosestFibonacci(6);

        result.Item1.ShouldBe(5);
        result.Item2.ShouldBe(8);
    }

    [Fact]
    public void GivenNumber13_ReturnsTupleOf13And21()
    {
        var result = _fibonacci.GetClosestFibonacci(13);

        result.Item1.ShouldBe(13);
        result.Item2.ShouldBe(21);
    }

    [Fact]
    public void GivenNumber89_ReturnsTupleOf89And144()
    {
        var result = _fibonacci.GetClosestFibonacci(89);

        result.Item1.ShouldBe(89);
        result.Item2.ShouldBe(144);
    }
}
In the example above, we created a test class called FibonacciSequenceTests that contains four unit tests.

The first test is for when the number to be tested is 0, the second test is for when the number is 6, the third test is for when the number is 13, and the fourth test is for when the number is 89. In each test, the expected result is compared to the actual result.