We have the following method.

public int Factorial(int number)
{
    int result = 1;
    for (int i = 1; i <= number; i++)
    {
        result *= i;
    }
    return result;
}

And we have two tests of this method.

[Fact]
void FactorialTest1()
{
    const int number = 4;

    int expectedResult = 1;
    for (int i = 1; i <= number; i++)
    {
        expectedResult *= i;
    }

    var actualResult = Factorial(number);

    Assert.Equal(expectedResult, actualResult);
}

[Fact]
void FactorialTest2()
{
    const int number = 4;
    const int expectedResult = 24;

    var actualResult = Factorial(number);

    Assert.Equal(expectedResult, actualResult);
}

Which of these tests is more correct?

The first test completely duplicates the code of the Factorial method. It seems wrong to me