Defect density and detection rate in Testing Fundamentals - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Defect Density Calculation

Imagine a software module has 50 defects found during testing. The module size is 10,000 lines of code. What is the defect density?

A 0.5 defects per line of code

B 0.005 defects per line of code

C 0.05 defects per line of code

D 5 defects per line of code

💡 Hint

Defect density = Number of defects / Size of code.

Defect density is calculated by dividing the number of defects by the size of the code. Here, 50 defects / 10,000 lines = 0.005 defects per line.

🧠 Conceptual

intermediate

Calculating Defect Detection Rate

A testing team found 80 defects in the first week and 40 defects in the second week. If the total defects found after two weeks is 120, what is the defect detection rate for the second week?

A 40%

B 50%

C 66.7%

D 33.3%

💡 Hint

Defect detection rate = (Defects found in period / Total defects found) * 100%

Second week detection rate = (40 / 120) * 100% = 33.3%

❓ Predict Output

advanced

Output of Defect Density Calculation Code

What is the output of this Python code?

Testing Fundamentals

def calculate_defect_density(defects, lines_of_code):
    return defects / lines_of_code

result = calculate_defect_density(25, 5000)
print(f"Defect Density: {result:.4f}")

A Defect Density: 0.0250

B Defect Density: 0.0500

C Defect Density: 0.0050

D Defect Density: 0.0005

💡 Hint

Divide defects by lines of code and format to 4 decimals.

25 defects / 5000 lines = 0.005. Formatted to 4 decimals: 0.0050.

❓ assertion

advanced

Assertion for Defect Detection Rate

Which assertion correctly verifies that the defect detection rate is 40% when 20 defects are found out of 50 total defects?

Testing Fundamentals

defect_found = 20
total_defects = 50
detection_rate = (defect_found / total_defects) * 100

A assert detection_rate == 40

B assert detection_rate == 0.4

C assert detection_rate == 0.40

D assert detection_rate == 4

💡 Hint

Remember detection_rate is a percentage, not a fraction.

The detection_rate is (20/50)*100 = 40. So the assertion must check for 40, not 0.4.

🔧 Debug

expert

Debugging Defect Density Calculation Error

What error will this code raise when calculating defect density?

defect_count = '30'
lines_of_code = 10000
defect_density = defect_count / lines_of_code
print(defect_density)

Testing Fundamentals

defect_count = '30'
lines_of_code = 10000
defect_density = defect_count / lines_of_code
print(defect_density)

A TypeError: unsupported operand type(s) for /: 'str' and 'int'

B ZeroDivisionError: division by zero

C NameError: name 'defect_count' is not defined

D SyntaxError: invalid syntax

💡 Hint

Check the data types of variables used in division.

defect_count is a string, lines_of_code is an integer. Dividing string by int causes TypeError.