Path Coverage

測試code所有可能的路徑

Example 1

if x > 3:
	print "Hi"
else:
	print "Bye"
if y = 5:
	print "Good"
else:
	print "Bad"

Path coverage

總共會有4個test cases => 每個path都要清到

Example 2

input A & B
C = A + B
if C > 100:
	print "ITS DONE"

if A > 50:
	print "ITS PENDING"
END IF

Path coverage

總共會有4個test cases => 每個path都要清到

1. A = 60, B = 50
2. A = 20, B = 100
3. A = 60, B = 10
4. A = 20, B = 10

Example 3

def foo(x, y):
	for i in range(x):
		something()
	if y:
		somethingElse()

Path coverage

以這種情形來說，沒有辦法去測試所有的Path，因為可能有無限個X的值，所以沒辦法達到100% Path coverage
這種情形又稱為 exhaustive testing，所以大多數的時候，Path coverage 100% 是沒有辦法達到的

Modified Condition Decision Coverage (MCDC)

• 是condition Coverage和Decision Coverage的混合
• 在safety-critical application中是必要的
• IDEA: 只測試重要的condition的組合和limit testing cost
• 通常是用在有很多的condition的情形，並且不知道要測哪些才算有效的測試
• 以結果論來說4個條件我們會有5個test cases, 10個條件會有11個test cases而不是1024個

Example 1

def x(a, b, c):
	if a & b & c:
		print("Hi")

MCDC Coverage

可能的測項

這時我們要找一個條件是會影響到outcome的

• TC1和TC5符合我們測試A的要求，並且BC不變
• TC1和TC3符合我們測試B的要求，並且AC不變
• TC1和TC2符合我們測試C的要求，並且AB不變

所以總結來說，我們只要測試以下測項就能達到100% MCDC Coverage

Example 2

def x(a, b, c):
	if a | b & c:
		print("Hi")

MCDC Coverage

可能的測項

• TC2和TC6符合我們測試A的要求，並且BC不變
• TC5和TC7符合我們測試B的要求，並且AC不變
• TC5和TC6符合我們測試C的要求，並且AB不變

所以總結來說，我們只要測試以下測項就能達到100% MCDC Coverage

Loop Testing

• 通常是用在當有loop在code裡面

Example1

count = int(input("enter your number"))
while (couont < 20) & (count > 0):
	print(f"The count is: {count}")
	count = count + 1
print("Good bye!")

Loop Coverage

Steps:

1. Skip the entire loop: count = 20
2. Make 1 passes through the loop: count = 19
3. Make 2 passes through the loop: count = 18
4. Make a random number of passes through the loop: count = 10
5. Make n, n-1, n+1 passed through the loop:
   couont = 1, count = 0, count = 2

Example2

count_1 = int(input("enter first number"))
count_2 = int(input("enter second number"))
for i in range(count_1):
	for j in range(count_2):
		print(i, j)
		if i > 20 or j > 20:
			break
print("Good bye!")

Loop Coverage

Steps:

1. Skip the entire loop: count_1 = 1, count_2 = 0
2. Make 1 passes through the loop: count_1 = 1, count_2 = 1
3. Make 2 passes through the loop: count_1 = 1, count_2 = 2
4. Make a random number of passes through the loop: count_1 = 1, count_2 = 5
5. Make n, n-1, n+1 passed through the loop: 可以為無限值

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