Unit testing

• Testing ensures software meets design requirements (SPECification)
• Finds Bugs - Logic errors

• But what about Syntax errors?

• Unit - Smallest components of a program that can be tested

• e.g. Loop, Function, etc.
• Usually automated - much faster so allows more testing
• Test Cases (Chapter 1)
• Unit test is just another piece of code!
• Passes parameters (Arguments) to the Function
• Unit Test calculates (or holds) the "Expected Value"
• Function returns the "Actual Value"
• Unit test code must be written independently
• Otherwise it's a pointless exercise (Programmers' Bias)

Simple Unit Test

print("Unit testing")
print("============")

def volumeOfCylinder(radiusIN, heightIN):
    volume = 3.14 * (radiusIN ** 2) * heightIN
    return volume
def unitTest():
    testR = 2
    testH = 1
    expectedVal = 3.14 * (testR ** 2) * testH
    actualVal = volumeOfCylinder(testR, testH)
    passed = True
    if expectedVal != actualVal:
        passed = False
    return passed
print(f"Test passed {unitTest()}")

Automated Unit Test with 25 cases

print("Function TEST")
def addNums(x,y):
    return(x+y)

print("i    j    Expected    Actual")
testPass = True
for i in range(5):
    for j in range(5):
        expectedResult = i + j
        actualResult = addNums(i,j)
        print(i, " ", j, "    ", expectedResult, "     ", actualResult)
        if expectedResult != actualResult:
            testPass = False
print("Test passed? ", testPass)

Automated Unit test with Array of cases

print("UnitTest_ReturnValue1") 
print("Unit Test Demo")

#First let's define the volume() Function def volumeOfCylinder (radius IN, heightIN): volume = 3.14 * (radiusIN ** 2)* height IN return volume

#Now let's define the unitTest() Function 
def VolumeOfCylinder(radiusIN, heightIN):
    volume = 3.14 * (radiusIN ** 2) * heightIN
    return volume

def unitTest():
    testRs = [2, 4, 6, 10]
    testHs = [1, 2, 3, 5]
    success = 0
    successful = ""

    for i in range (len(testRs)): 
        testR = testRs[i] 
        testH = testHs[i] 
        expectedVal = 3.14 * (testR ** 2) * testH 
        actualVal = volumeOfCylinder (testR, testH) 
        if expectedVal == actualVal:
            success = success + 1 
    successful = str(success) + "/" + str(len(testRs))

    return successful
#Now we need to call the unitTest() Function

#This is the only code in the Program Body! 
print("Test passed: ", unitTest())