CH01. L03. 7 testing principles

Summary

The video script discusses the 7 Testing Principles, emphasizing early testing to detect defects, avoiding the fallacy of absence of errors, focusing on defect discovery, recognizing testing's context dependency, and addressing principles like defect clustering, the pesticide paradox, and the impossibility of exhaustive testing. It encourages understanding each principle to guide effective software testing.

Takeaways

• 📅 Early testing is crucial for identifying defects early in the software development lifecycle.
• 🙅‍♂️ The Absence-of-errors fallacy highlights that a system based on wrong requirements is unacceptable, regardless of the number of defects found.
• 🔎 The primary goal of testing is to find defects, not to prove the absence of them.
• 🌐 Testing is context dependent, meaning the approach varies based on the type of software and business domain.
• 🚨 Defect clustering suggests focusing testing efforts on modules expected to have more defects, following the 80/20 Pareto principle.
• 🐞 The Pesticide paradox warns against using the same test cases repeatedly, as they may become ineffective over time.
• 🔄 To overcome the Pesticide paradox, test cases should be modified to uncover new bugs that were previously undetected.
• ❌ Exhaustive testing is impossible due to the vast number of input combinations and preconditions.
• 🔍 Risk analysis and prioritization are used instead of exhaustive testing to identify high-risk modules for focused testing efforts.
• 📚 Reviewing the '7 Testing Principles' document is essential for a deeper understanding of each principle.

Q & A

What are the 7 Testing Principles mentioned in the script?

The 7 Testing Principles are: 1) Early testing, 2) Absence-of-errors fallacy, 3) Testing shows presence of defects, 4) Testing is context dependent, 5) Defect clustering, 6) Pesticide paradox, and 7) Exhaustive testing is impossible.

What does the principle of 'Early testing' suggest?

The principle of 'Early testing' suggests that testing should start as early as possible in all stages of the software development life cycle to discover defects early.

What is the 'Absence-of-errors fallacy' and why is it important?

The 'Absence-of-errors fallacy' is the misconception that if no defects are found, the system is error-free. It's important because it emphasizes that a system based on wrong requirements is unacceptable, regardless of the number of defects found.

What is the main goal of testing according to the third principle?

The main goal of testing, according to the third principle, is to find defects, not to prove that there are no defects in the software.

What does 'Testing is context dependent' mean and why is it significant?

'Testing is context dependent' means that the testing approach varies based on the type of software and business domain. It's significant because it highlights the need for tailored testing strategies for different contexts, such as safety-critical software versus e-commerce sites.

Can you explain the 'Defect clustering' principle?

The 'Defect clustering' principle suggests focusing testing efforts on modules expected to have more defects, based on the Pareto principle, which states that 80% of problems are found in 20% of modules.

What is the 'Pesticide paradox' and how can it be overcome?

The 'Pesticide paradox' refers to the phenomenon where using the same test cases repeatedly on modified software fails to reveal new defects. It can be overcome by modifying the test cases to ensure they uncover new bugs.

Why is 'Exhaustive testing' considered impossible?

'Exhaustive testing' is considered impossible because it would require testing all combinations of inputs and preconditions, which is impractical. Instead, risk analysis and prioritization are used to focus on high-risk modules.

How does the script relate the Pareto principle to software testing?

The script relates the Pareto principle to software testing by suggesting that 80% of bugs are found in 20% of the modules, indicating that testing efforts should be concentrated on those areas.

What is the recommended approach to determine how much testing is needed, as mentioned in the script?

The recommended approach to determine how much testing is needed is through risk analysis and prioritization, focusing on modules with higher risk rather than attempting exhaustive testing.

Where can one find more information about 'How Much Testing is enough?' as mentioned in the script?

More information about 'How Much Testing is enough?' can be found in the syllabus, specifically in section 1.1.5.