Defect classification (severity, priority) in Testing Fundamentals - Build an Automation Script

Classify defects by severity and priority

Preconditions (2)

Step 1: Review each defect description

Step 2: Assign a severity level: Critical, Major, Minor, or Trivial

Step 3: Assign a priority level: High, Medium, or Low

Step 4: Verify that severity and priority are assigned correctly according to rules

Step 5: Rules: Critical severity means High priority, Minor severity means Low priority, Major severity usually Medium priority

✅ Expected Result: Each defect is correctly classified with severity and priority matching the rules

Automation Requirements - pytest

Assertions Needed:

Assert severity is one of ['Critical', 'Major', 'Minor', 'Trivial']

Assert priority is one of ['High', 'Medium', 'Low']

Assert priority matches severity rules

Best Practices:

Use parameterized tests for multiple defects

Use clear assertion messages

Keep classification logic separate from test code

Automated Solution

Testing Fundamentals

import pytest

# Function to classify priority based on severity

def classify_priority(severity: str) -> str:
    severity = severity.lower()
    if severity == 'critical':
        return 'High'
    elif severity == 'major':
        return 'Medium'
    elif severity == 'minor':
        return 'Low'
    elif severity == 'trivial':
        return 'Low'
    else:
        raise ValueError(f"Unknown severity level: {severity}")

# Sample defects data
sample_defects = [
    {'id': 1, 'description': 'App crashes on launch', 'severity': 'Critical', 'priority': 'High'},
    {'id': 2, 'description': 'UI alignment issue', 'severity': 'Minor', 'priority': 'Low'},
    {'id': 3, 'description': 'Slow response time', 'severity': 'Major', 'priority': 'Medium'},
    {'id': 4, 'description': 'Typo in help text', 'severity': 'Trivial', 'priority': 'Low'}
]

@pytest.mark.parametrize('defect', sample_defects)
def test_defect_classification(defect):
    severity = defect['severity']
    priority = defect['priority']

    # Check severity is valid
    assert severity in ['Critical', 'Major', 'Minor', 'Trivial'], \
        f"Severity '{severity}' is not valid"

    # Check priority is valid
    assert priority in ['High', 'Medium', 'Low'], \
        f"Priority '{priority}' is not valid"

    # Check priority matches severity rules
    expected_priority = classify_priority(severity)
    assert priority == expected_priority, \
        f"Priority '{priority}' does not match expected '{expected_priority}' for severity '{severity}'"

This test script uses pytest to automate defect classification verification.

The classify_priority function defines the expected priority for each severity level. This keeps logic separate and clear.

The sample_defects list contains example defects with their severity and priority.

The test test_defect_classification runs for each defect using pytest.mark.parametrize. It asserts that severity and priority values are valid and that priority matches the expected value based on severity.

This approach is simple, clear, and easy to extend with more defects.

Common Mistakes - 3 Pitfalls

Hardcoding priority values in test without using a classification function

Not validating severity and priority values before assertions

Using print statements instead of assertions for verification

Bonus Challenge

Now add data-driven testing with 3 different defect inputs including edge cases

Show Hint

Practice

1.

What does severity indicate in defect classification?

easy

A. How serious or harmful the defect is

B. How soon the defect should be fixed

C. Who reported the defect

D. The number of times the defect occurred

Solution

1. Step 1: Understand the meaning of severity

   Severity measures the impact or seriousness of a defect on the system or user.

2. Step 2: Differentiate severity from priority

   Priority is about scheduling the fix, not the defect's impact.

3. Final Answer:

   How serious or harmful the defect is -> Option A

4. Quick Check:

   Severity = seriousness [OK]

Hint: Severity = impact level, not fix timing [OK]

Common Mistakes:

• Confusing severity with priority
• Thinking severity means who found the bug
• Assuming severity counts defect occurrences

2.

Which of the following is the correct way to classify a defect with high severity and low priority?

easy

A. A defect that is not serious and can be ignored

B. A defect that causes major system failure but can be fixed later

C. A minor UI glitch that must be fixed immediately

D. A defect that is serious and must be fixed immediately

Solution

1. Step 1: Understand high severity

   High severity means the defect causes major problems or failures.

2. Step 2: Understand low priority

   Low priority means the defect fix can be delayed or scheduled later.

3. Final Answer:

   A defect that causes major system failure but can be fixed later -> Option B

4. Quick Check:

   High severity + low priority = serious but delayed fix [OK]

Hint: High severity ≠ immediate fix if priority is low [OK]

Common Mistakes:

• Assuming high severity always means high priority
• Mixing up severity and priority meanings
• Ignoring the priority when severity is high

3.

Consider this defect list with severity and priority:
defects = [{'id':1, 'severity':'High', 'priority':'Low'}, {'id':2, 'severity':'Low', 'priority':'High'}, {'id':3, 'severity':'Medium', 'priority':'Medium'}]
Which defect should be fixed first based on priority?

medium

A. Defect with id 2

B. Defect with id 1

C. Defect with id 3

D. All defects have same priority

Solution

1. Step 1: Check priority values of each defect

   Defect 1 has priority Low, Defect 2 has priority High, Defect 3 has priority Medium.

2. Step 2: Determine which priority is highest

   High priority means fix first, so Defect 2 should be fixed first.

3. Final Answer:

   Defect with id 2 -> Option A

4. Quick Check:

   Highest priority = fix first [OK]

Hint: Fix defects with highest priority first [OK]

Common Mistakes:

• Choosing based on severity instead of priority
• Assuming Medium priority is higher than High
• Ignoring priority values

4.

Find the error in this defect classification code snippet:

def classify_defect(severity, priority):
    if severity == 'High' and priority == 'High'
        return 'Fix Immediately'
    else:
        return 'Schedule Fix'

medium

A. Function missing return statement

B. Wrong comparison operator used

C. Missing colon after if condition

D. Indentation error in else block

Solution

1. Step 1: Check syntax of if statement

   The if statement lacks a colon at the end of the condition line.

2. Step 2: Verify other parts of the function

   Return statements and else block indentation are correct.

3. Final Answer:

   Missing colon after if condition -> Option C

4. Quick Check:

   if condition must end with ':' [OK]

Hint: Check colons after if/else statements [OK]

Common Mistakes:

• Forgetting colon after if condition
• Misplacing indentation in else block
• Assuming missing return statement

5.

You have a list of defects with severity and priority:
defects = [{'id':101, 'severity':'Medium', 'priority':'High'}, {'id':102, 'severity':'High', 'priority':'Low'}, {'id':103, 'severity':'Low', 'priority':'Medium'}]
Write a Python expression using dictionary comprehension to create a dictionary mapping defect id to 'Fix Immediately' if priority is High, else 'Fix Later'.

hard

A. {d['id']: ('Fix Immediately' if d['priority'] == 'High') else 'Fix Later' for d in defects}

B. {d['id']: 'Fix Immediately' if d['priority'] == 'High' for d in defects}

C. {d['id']: 'Fix Immediately' if d['priority'] = 'High' else 'Fix Later' for d in defects}

D. {d['id']: ('Fix Immediately' if d['priority'] == 'High' else 'Fix Later') for d in defects}

Solution

1. Step 1: Understand dictionary comprehension syntax

   It uses {key: value for item in iterable} with conditional expressions inside value.

2. Step 2: Check conditional expression correctness

   {d['id']: ('Fix Immediately' if d['priority'] == 'High' else 'Fix Later') for d in defects} correctly uses parentheses and '==' for comparison inside the expression.

3. Final Answer:

   {d['id']: ('Fix Immediately' if d['priority'] == 'High' else 'Fix Later') for d in defects} -> Option D

4. Quick Check:

   Correct dict comprehension with conditional [OK]

Hint: Use parentheses around if-else in dict comprehension [OK]

Common Mistakes:

• Using single '=' instead of '==' in condition
• Missing parentheses around conditional expression
• Placing else outside parentheses