Another Solution: test more exceptions

def fib(n):
    var_type = type(n).__name__
    if var_type != 'int':
        raise ValueError(f'Invalid value type of "{n}" is "{var_type}"')
    if n < 1:
        raise ValueError(f'Invalid parameter {n} is negative')
    a, b = 1, 1
    for _ in range(1, n):
        a, b = b, a+b
    return a

import pytest
from fibonacci import fib

def test_fib():
    assert fib(10) == 55

def test_fib_negative():
    with pytest.raises(Exception) as err:
        fib(-1)
    assert err.type == ValueError
    assert str(err.value) == 'Invalid parameter -1 is negative'

def test_fib_negative_again():
    with pytest.raises(ValueError) as err:
        fib(-1)
    assert str(err.value) == 'Invalid parameter -1 is negative'

def test_fib_floating_point():
    with pytest.raises(ValueError) as err:
        fib(3.5)
    assert str(err.value) == 'Invalid value type of "3.5" is "float"'

def test_fib_small_floating_point():
    with pytest.raises(ValueError) as err:
        fib(0.5)
    assert str(err.value) == 'Invalid value type of "0.5" is "float"'

def test_fib_big_floating_point():
    with pytest.raises(ValueError) as err:
        fib(3.0)
    assert str(err.value) == 'Invalid value type of "3.0" is "float"'

Output:

============================= test session starts ==============================
platform linux -- Python 3.13.7, pytest-9.0.2, pluggy-1.6.0
rootdir: /home/gabor/github/code-maven.com/python.code-maven.com
configfile: pyproject.toml
plugins: anyio-4.12.0, cov-7.0.0
collected 6 items

test_fibonacci.py ......                                                 [100%]

============================== 6 passed in 0.04s ===============================