Test coverage of branches and loops

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. A program has an if, an elif and an else. Which set of tests gives full branch coverage?

A At least one test that runs the if, one that runs the elif and one that runs the else

B Three tests that all run the if branch with different numbers

2. Code: if mark >= 50: print('Pass') else: print('Fail'). A student only tests mark = 80. What is untested?

A The else branch

B The if branch

3. Which loop test checks that a for loop copes with an empty list?

A Running it many times

B Running it zero times

4. Full loop coverage means testing a loop running...

A only the maximum number of times

B zero times, once and many times

5. After testing, the coverage check shows one line inside an elif was never run. What does this tell you?

A That line is untested and could hide a bug

B That line must be correct because it never caused an error

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1if mark >= 50: print("Pass") else: print("Fail")		AThe loop was only tested running many times. It was never tested running zero times (count = 0) or once (count = 1), so edge bugs could be missed.
2for item in cart: total += item		BTest the loop with an empty list (zero times), a one-item list (once) and a longer list (many times).
3Every branch of an if/elif/else needs its own test value, so three branches need at least three tests.		Cif score >= 80: grade = "A" elif score >= 50: grade = "B" else: grade = "C"
4A loop that never runs when given an empty list shows the zero-times case, and any code inside it stays untested.		DOnly age 20 was tested, so the else branch never ran. The Minor line is untested code. Add a test such as age 10.
5# Tests run: age = 20 only if age >= 18: print("Adult") else: print("Minor")		ENeeds at least two tests for full branch coverage: one mark that is 50 or more and one that is below 50.
6# Tests run: count = 5 only while count > 0: count -= 1		Ffor n in []: print(n)

Definitions

test coverage

Fill in the Blanks

Complete each line of code by filling in the missing parts.

if mark >= 50: print("Pass") ____:

items = [] ___ x in items: print(x)

count = 0 for i in range(_): count += 1

for n in [2, 4, 6]: total __ n print(total)

if age < 13: print("Child") ____ age < 20:

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A def sign(n):

B if n > 0

C return 'pos'

D elif n < 0:

E return 'neg'

F return 'zero'

Question 2

A items = []

B total = 1

C for x in items:

D total += x

E print(total)

Question 3

A def count_pos(nums):

B c = 0

C for n in nums:

D if n < 0:

E c += 1

F return c

Question 4

A def total(nums):

B t = 0

C for n in nums:

D t = n

E return t

F print(total([]))

Question 5

A mark = 75

B if mark => 80:

C print('High')

D else:

E print('Low')

Answer Key

Test coverage of branches and loops

Section A: Quick Questions

A — At least one test that runs the if, one that runs the elif and one that runs the else

A — The else branch

B — Running it zero times

B — zero times, once and many times

A — That line is untested and could hide a bug

Section B: Match the Pairs

if mark >= 50: print("Pass") else: print("Fail") → Needs at least two tests for full branch coverage: one mark that is 50 or more and one that is below 50.

for item in cart: total += item → Test the loop with an empty list (zero times), a one-item list (once) and a longer list (many times).

Every branch of an if/elif/else needs its own test value, so three branches need at least three tests. → if score >= 80: grade = "A" elif score >= 50: grade = "B" else: grade = "C"

A loop that never runs when given an empty list shows the zero-times case, and any code inside it stays untested. → for n in []: print(n)

# Tests run: age = 20 only if age >= 18: print("Adult") else: print("Minor") → Only age 20 was tested, so the else branch never ran. The Minor line is untested code. Add a test such as age 10.

# Tests run: count = 5 only while count > 0: count -= 1 → The loop was only tested running many times. It was never tested running zero times (count = 0) or once (count = 1), so edge bugs could be missed.

Section C: Definitions

test coverage — Testing so that every if/elif/else branch runs at least once and every loop is tried running zero times, once and many times. Any code never run is untested.

Section D: Fill in the Blanks

if mark >= 50:
    print("Pass")
else:

items = []
for x in items:
    print(x)

count = 0
for i in range(1):
    count += 1

for n in [2, 4, 6]:
    total += n
print(total)

if age < 13:
    print("Child")
elif age < 20:

Section E: Spot the Error

B — An if statement must end with a colon, so this line should be 'if n > 0:'. Once it is fixed, full branch coverage needs tests such as 5, -3 and 0 so every branch runs.

B — A total must start at 0. With an empty list the loop runs zero times, so the program would print 1 instead of 0. It should be 'total = 0'. This is why testing the zero-times case matters.

D — The function should count positive numbers, so the condition must be 'n > 0'. Tests with [], [4] and [3, -1, 5] (loop zero, once and many times) would show the wrong counts.

D — 't = n' replaces the total each time instead of adding to it. It should be 't += n'. A test with one item would still pass, so only a loop-many-times test such as [2, 3, 4] reveals the bug.

B — '=>' is not a valid Python operator. It should be '>='. Testing with 75 only runs the else branch, so a second test such as 80 or more is needed to cover the if branch.