Defect metrics in Testing Fundamentals - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Defect Density

Which formula correctly calculates defect density in a software project?

A Number of defects fixed divided by the total number of defects reported

B Total number of test cases executed divided by the number of defects found

C Number of defects found divided by the size of the software (e.g., lines of code or function points)

D Total number of defects found divided by the number of testers involved

💡 Hint

Think about how many defects appear relative to the size of the software.

Defect density measures how many defects exist per unit size of software, helping to understand quality relative to software size.

🧠 Conceptual

intermediate

Interpreting Defect Leakage

What does defect leakage indicate in software testing?

A Defects that remain undetected and are found by users after release

B Defects found by the testing team during test execution

C Defects fixed but reintroduced in later versions

D Defects reported but rejected as invalid

💡 Hint

Consider defects that escape the testing process and reach the users.

Defect leakage measures the number of defects missed during testing but found by users, indicating gaps in testing.

❓ Predict Output

advanced

Calculate Defect Removal Efficiency (DRE)

Given the following data, what is the Defect Removal Efficiency (DRE)?

DRE = (Defects found before release) / (Defects found before release + Defects found after release)

Defects found before release = 120
Defects found after release = 30

A 0.80

B 0.85

C 0.75

D 0.70

💡 Hint

Calculate the ratio of defects found before release to total defects found.

DRE = 120 / (120 + 30) = 120 / 150 = 0.80.

❓ assertion

advanced

Assertion on Defect Arrival Rate

Which assertion correctly describes the defect arrival rate during testing?

A It is the ratio of defects reopened to defects closed

B It is the number of defects found per unit time during testing

C It is the number of defects fixed per day after release

D It is the total number of defects found divided by total test cases executed

💡 Hint

Think about how quickly defects are discovered over time.

Defect arrival rate measures how many defects are found in a given time period during testing.

🔧 Debug

expert

Identify the Incorrect Defect Metric Calculation

Which option shows an incorrect calculation of a defect metric?

A Defect Arrival Rate = Defects found per day during testing

B Defect Leakage = Defects found after release / Total Defects found

C Defect Density = Total Defects / Total Lines of Code

D Defect Removal Efficiency = Defects found after release / Total Defects found

💡 Hint

Review the formula for Defect Removal Efficiency carefully.

Defect Removal Efficiency is the ratio of defects found before release to total defects found, not defects found after release.