Question

Q2. Booleans and testing (a) Define the following function. 4 marks def valid(x, y, z): #valid takes three numbers and it returns True iff #at least one of them is positive and at most one of them is negative (b) Define the following function. 6 marks def test_valid(): #test_valid returns True iff valid is correct test_valid should perform a set of well-chosen tests on valid, with at least eight tests.

Hi, This question is from python unit

Answer 1

def valid(x,y,z):
    positives = 0
    negatives = 0
    if(x>0):
        positives+=1
    if (y > 0):
        positives += 1
    if (z > 0):
        positives += 1
    if (x < 0):
        negatives += 1
    if (y < 0):
        negatives += 1
    if (z < 0):
        negatives += 1
    if(positives>=1 and negatives<=1):
        return True
    else:
        return False
    
def test_valid():
    print(valid(1,2,3))
    print(valid(-1, -2, -3))
    print(valid(-1, -2, 3))
    print(valid(-1, 2, 3))
    print(valid(1, -2, -3))
    print(valid(1, -2, 0))
    print(valid(1, 0, 0))
    print(valid(0, 5, 0))