Error guessing in Testing Fundamentals - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Error guessing in software testing?

Error guessing is a testing technique where testers use their experience to guess the most error-prone areas of the software and design test cases to find defects there.

beginner

Why is experience important in error guessing?

Experience helps testers predict where errors are likely to occur based on past bugs, common mistakes, and tricky parts of the software.

intermediate

How does error guessing differ from formal test design techniques?

Error guessing is informal and based on intuition and experience, while formal techniques use systematic methods and rules to design tests.

beginner

Give an example of an error guessing test case.

If a form requires a date, an error guessing test might try entering an invalid date like February 30 or letters instead of numbers to check how the system handles it.

intermediate

What is a limitation of error guessing?

It depends heavily on tester skill and experience, so it might miss errors if the tester is not familiar with the application or common bugs.

What does error guessing rely on most?

A Automated tools

B Tester experience and intuition

C Formal test cases

D Random input generation

Error guessing depends on the tester's experience and intuition to find likely error spots.

Which of these is an example of error guessing?

A Following a test script exactly

B Testing boundary values systematically

C Trying invalid inputs based on past bugs

D Using a checklist for requirements

Trying invalid inputs based on past bugs is a classic error guessing approach.

Error guessing is best described as:

A A formal testing method

B A random testing technique

C A tool-based testing method

D An experience-based testing technique

Error guessing is based on tester experience and intuition.

What is a risk of relying only on error guessing?

A Missing defects due to lack of experience

B Too many automated tests

C Over-documentation of tests

D Ignoring user requirements

Without experience, testers may miss important defects.

Which is NOT a characteristic of error guessing?

A Systematic and rule-based

B Depends on tester knowledge

C Focuses on error-prone areas

D Uses tester intuition

Error guessing is informal and not systematic or rule-based.

Explain what error guessing is and why it is useful in software testing.

Think about how testers use their past knowledge to find bugs.

Describe a situation where error guessing might help find a bug that formal test cases miss.

Consider unusual or invalid inputs that testers might try based on experience.

Practice

1. What is the main idea behind Error guessing in software testing?

easy

A. Using formal test cases only

B. Writing automated tests for every function

C. Guessing where errors might occur based on experience

D. Ignoring past bugs and testing randomly

Solution

1. Step 1: Understand the concept of error guessing

   Error guessing is a technique where testers use their experience to predict where bugs might be.

2. Step 2: Compare options with the concept

   Only Guessing where errors might occur based on experience matches the idea of using experience to guess errors, others describe different testing methods.

3. Final Answer:

   Guessing where errors might occur based on experience -> Option C

4. Quick Check:

   Error guessing = Experience-based bug prediction [OK]

Hint: Error guessing is about experience, not formal rules [OK]

Common Mistakes:

• Confusing error guessing with automated testing
• Thinking error guessing ignores tester knowledge
• Believing error guessing is random testing

2. Which of the following is a correct example of an error guessing test case?

easy

A. Test all buttons for correct color

B. Test the software without any plan

C. Test only the homepage layout

D. Test input with empty fields to check validation

Solution

1. Step 1: Identify error guessing test case traits

   Error guessing focuses on inputs or actions likely to cause errors, like empty fields.

2. Step 2: Evaluate each option

   Test input with empty fields to check validation tests empty input, a common error source. Others are unrelated or random.

3. Final Answer:

   Test input with empty fields to check validation -> Option D

4. Quick Check:

   Empty input tests = Error guessing [OK]

Hint: Look for tests targeting likely error spots [OK]

Common Mistakes:

• Choosing tests unrelated to error conditions
• Confusing UI checks with error guessing
• Selecting random or unplanned tests

3. Given this scenario: A login form accepts username and password. Which input is best for error guessing?

medium

A. Username: 'admin', Password: '1234'

B. Username: '', Password: ''

C. Username: 'user1', Password: 'password'

D. Username: 'test', Password: 'test123'

Solution

1. Step 1: Identify inputs likely to cause errors

   Empty username and password fields often cause validation errors.

2. Step 2: Compare options for error likelihood

   Username: '', Password: '' uses empty inputs, which is a common error guess. Others are normal inputs.

3. Final Answer:

   Username: '', Password: '' -> Option B

4. Quick Check:

   Empty inputs = Common error guess [OK]

Hint: Empty or invalid inputs are classic error guesses [OK]

Common Mistakes:

• Choosing normal valid inputs
• Ignoring empty or boundary inputs
• Assuming random inputs are best

4. You wrote an error guessing test for a form but it never finds bugs. What is the most likely problem?

medium

A. You guessed errors in unlikely places

B. You wrote too many test cases

C. You automated all tests

D. You tested only the UI colors

Solution

1. Step 1: Understand error guessing effectiveness

   Error guessing works best when testers guess likely error spots based on experience.

2. Step 2: Analyze why tests fail to find bugs

   If guesses are in unlikely places, bugs won't be found. Other options don't explain this well.

3. Final Answer:

   You guessed errors in unlikely places -> Option A

4. Quick Check:

   Wrong guess spots = No bugs found [OK]

Hint: Guess where errors usually happen, not random places [OK]

Common Mistakes:

• Thinking more tests always find more bugs
• Believing automation replaces error guessing
• Focusing on UI style instead of error sources

5. You want to use error guessing to test a calculator app. Which combination of inputs is best to find errors?

hard

A. Very large numbers, zero, and dividing by zero

B. Random letters instead of numbers

C. Only positive integers

D. Normal numbers like 5 + 3, 10 - 2

Solution

1. Step 1: Identify error-prone inputs for calculator

   Calculators often fail with large numbers, zero, or division by zero.

2. Step 2: Evaluate options for error guessing effectiveness

   Very large numbers, zero, and dividing by zero targets these error-prone inputs, while others do not or are invalid inputs.

3. Final Answer:

   Very large numbers, zero, and dividing by zero -> Option A

4. Quick Check:

   Edge and invalid inputs = Best error guesses [OK]

Hint: Test edge cases and invalid inputs for errors [OK]

Common Mistakes:

• Testing only normal inputs
• Ignoring division by zero errors
• Using completely invalid inputs without context