#exercise 3.7 from A primer...

#a) function for computing the sum:
def sum_1k(M):
    s = 0.0
    for k in range(1,M+1):
        s = s + 1.0/k
    return s

#b) test function
def test_sum_1k():
    expected = 11.0/6
    computed = sum_1k(3)
    tol = 1e-10
    success = abs(expected-computed) < tol
    msg = f'Expected {expected}, but got {computed}'
    assert success, msg

"""
About calling test functions:
If we include a call to the test function here, the test is run
when we type 'python sum_func.py' in the terminal window.
Alternatively, we can run 'pytest sum_func.py', which will run
all test functions found in the file, regardless of whether or not
they are called."""

test_sum_1k()

"""
Terminal> python sum_func.py
no output
"""