Defect density and detection rate in Testing Fundamentals - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to calculate defect density given total defects and size.

Testing Fundamentals

defect_density = total_defects / [1]

Drag options to blanks, or click blank then click option'

Asize

Btotal_defects

Ctime

Dtest_cases

Attempts:

3 left

💡 Hint

Common Mistakes

Dividing defects by time instead of size.

Using total defects twice in the calculation.

Defect density is calculated as total defects divided by the size of the software (e.g., lines of code).

2fill in blank

medium

Complete the code to calculate defect detection rate given defects found and total defects.

Testing Fundamentals

detection_rate = defects_found / [1]

Drag options to blanks, or click blank then click option'

Adefects_found

Btotal_defects

Ctest_cases

Dtime_spent

Attempts:

3 left

💡 Hint

Common Mistakes

Dividing defects found by defects found (always 1).

Using test cases or time instead of total defects.

Defect detection rate is the ratio of defects found to total defects present.

3fill in blank

hard

Fix the error in the code to calculate defect density correctly.

Testing Fundamentals

defect_density = [1] / size

Drag options to blanks, or click blank then click option'

Asize

Bdefects_found

Ctime

Dtotal_defects

Attempts:

3 left

💡 Hint

Common Mistakes

Using size as numerator causing density to be 1.

Using defects found instead of total defects.

The numerator should be total defects, not size or other values, to calculate defect density.

4fill in blank

hard

Fill both blanks to calculate defect detection rate as a percentage.

Testing Fundamentals

detection_rate = ([1] / [2]) * 100

Drag options to blanks, or click blank then click option'

Adefects_found

Btotal_defects

Ctest_cases

Dtime_spent

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping numerator and denominator.

Using test cases or time instead of defects counts.

Defect detection rate is defects found divided by total defects, multiplied by 100 to get percentage.

5fill in blank

hard

Fill all three blanks to create a dictionary with defect density and detection rate.

Testing Fundamentals

metrics = {"density": [1] / [2], "detection": ([3] / total_defects) * 100}

Drag options to blanks, or click blank then click option'

Atotal_defects

Bsize

Cdefects_found

Dtime_spent

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up variables for density and detection.

Using time_spent instead of size or defects.

The dictionary calculates defect density as total defects over size, and detection rate as defects found over total defects times 100.

Practice

1. What does defect density measure in software testing?

easy

A. Percentage of passed test cases

B. Total number of test cases executed

C. Number of defects per size of software

D. Time taken to fix defects

Solution

1. Step 1: Understand the definition of defect density

   Defect density is defined as the number of defects found divided by the size of the software (e.g., lines of code or function points).

2. Step 2: Compare options with the definition

   Only Number of defects per size of software correctly describes defect density as defects per size of software.

3. Final Answer:

   Number of defects per size of software -> Option C

4. Quick Check:

   Defect density = Defects / Size [OK]

Hint: Defect density = defects divided by software size [OK]

Common Mistakes:

• Confusing defect density with total defects
• Mixing defect density with test case count
• Thinking defect density measures fix time

2. Which formula correctly calculates the detection rate during testing?

easy

A. (Number of defects found) / (Total defects present)

B. (Total defects present) / (Number of defects found)

C. (Number of test cases passed) / (Total test cases)

D. (Number of defects fixed) / (Number of defects found)

Solution

1. Step 1: Recall detection rate meaning

   Detection rate measures how many defects testing finds out of all defects present.

2. Step 2: Match formula to definition

   (Number of defects found) / (Total defects present) correctly shows detection rate as defects found divided by total defects present.

3. Final Answer:

   (Number of defects found) / (Total defects present) -> Option A

4. Quick Check:

   Detection rate = Found / Total [OK]

Hint: Detection rate = defects found ÷ total defects [OK]

Common Mistakes:

• Reversing numerator and denominator
• Confusing detection rate with pass rate
• Using fixed defects instead of found defects

3. A software module has 5000 lines of code and 25 defects found. What is the defect density?

medium

A. 0.5 defects per line

B. 0.05 defects per line

C. 2 defects per line

D. 0.005 defects per line

Solution

1. Step 1: Apply defect density formula

   Defect density = Number of defects / Size of software = 25 / 5000.

2. Step 2: Calculate the value

   25 divided by 5000 equals 0.005 defects per line.

3. Final Answer:

   0.005 defects per line -> Option D

4. Quick Check:

   25 ÷ 5000 = 0.005 [OK]

Hint: Divide defects by lines of code for defect density [OK]

Common Mistakes:

• Multiplying instead of dividing
• Using wrong units or decimal places
• Confusing defect density with total defects

4. During testing, 40 defects were found but the total defects present were 50. The detection rate was calculated as 1.25. What is the error?

medium

A. Detection rate cannot be greater than 1

B. Detection rate should be less than 0.5

C. Detection rate equals defects fixed, not found

D. Detection rate is unrelated to defects

Solution

1. Step 1: Understand detection rate limits

   Detection rate is defects found divided by total defects, so it must be between 0 and 1.

2. Step 2: Check given value

   Given detection rate is 1.25, which is greater than 1, so it is invalid.

3. Final Answer:

   Detection rate cannot be greater than 1 -> Option A

4. Quick Check:

   Detection rate ≤ 1 [OK]

Hint: Detection rate max is 1 (100%) [OK]

Common Mistakes:

• Allowing detection rate > 1
• Mixing detection rate with fixed defects
• Ignoring ratio limits

5. A project has 10,000 lines of code with 80 defects found during testing. Later, 20 more defects were discovered after release. What is the updated defect density and detection rate?

hard

A. Defect density: 0.008; Detection rate: 1.0

B. Defect density: 0.01; Detection rate: 0.8

C. Defect density: 0.01; Detection rate: 1.0

D. Defect density: 0.008; Detection rate: 0.8

Solution

1. Step 1: Calculate total defects and defect density

   Total defects = 80 found + 20 discovered = 100. Defect density = total defects / lines of code = 100 / 10,000 = 0.01.

2. Step 2: Calculate detection rate

   Detection rate = defects found / total defects = 80 / 100 = 0.8.

3. Step 3: Match calculations to options

   Defect density is 0.01 and detection rate is 0.8, but Defect density: 0.008; Detection rate: 0.8 shows defect density as 0.008 which is incorrect. Defect density: 0.01; Detection rate: 0.8 shows correct defect density but detection rate 0.8. Defect density: 0.008; Detection rate: 0.8 has defect density 0.008 which is wrong. Defect density: 0.01; Detection rate: 0.8 matches defect density 0.01 and detection rate 0.8 correctly.

4. Final Answer:

   Defect density: 0.01; Detection rate: 0.8 -> Option B

5. Quick Check:

   Defect density = 100/10000=0.01; Detection rate = 80/100=0.8 [OK]

Hint: Add all defects for density; found ÷ total for detection rate [OK]

Common Mistakes:

• Using only found defects for defect density
• Ignoring defects found after release
• Mixing detection rate numerator and denominator