""""
Ex. 3.7 from "A Primer on...".
Write a function sum_1k(M) that computes and
returns a sum, and write a test function 
test_sum_1k()
"""

def sum_1k(M):
    s = 0
    for k in range(1,M+1):
        s += 1/k
    return s

#print(sum_1k(3))
    
# sum = 1 + 1/2 + 1/3 = 11/6

def test_sum_1k():
    M = 3
    tol = 1e-12

    expected = 11/6
    computed = sum_1k(M)
    #use a tolerance since we compare floats:
    success = abs(expected - computed) < tol
    assert success



#call the test function (should give no output if test passes):
test_sum_1k()

"""
Terminal> python sum_1k.py 
"""

"""
Alternatively, use pytest to run the test. Then you don't need 
the explicit call to the test function above, since pytest will
automatically find and run all test functions:
Terminal> pytest sum_1k.py 
===================================== test session starts ======================================
platform darwin -- Python 3.9.7, pytest-6.2.4, py-1.10.0, pluggy-0.13.1
rootdir: /Users/sundnes/Desktop/IN1900_9sep
plugins: anyio-2.2.0, mock-3.10.0, cov-3.0.0
collected 1 item                                                                               

sum_1k.py .                                                                              [100%]

====================================== 1 passed in 0.01s =======================================

"""