Week 1 - Introduction to Software Testing 

Overview of software testing

The importance of Quality Assurance and Testing

Roles in testing

Practice

Assignment

Tester Track

Learning Goals

• Explain what software testing is and why it matters
• Describe the main objectives of testing
• Explain the difference between testing and debugging
• Describe how testing contributes to product and business success
• Explain the relationship between error, defect, failure, and root cause
• Understand the seven principles of testing
• Distinguish between testing and quality assurance
• Describe key roles in testing, including the whole team approach and test independence

What is software testing?

Software testing is a set of activities used to evaluate the quality of software and related work products.

In simple words, testing helps us understand:

• whether the product works as expected
• whether it meets requirements
• whether it is fit for purpose
• whether important risks and defects are identified early

Testing includes both static and dynamic activities.

Static testing means checking work products without running the software. Examples include reviewing

requirements, user stories, test cases, design documents, and code.

Dynamic testing means running the software and observing how it behaves.

Testing is not only about finding bugs. It also helps teams understand quality, reduce risk, and make better

decisions.

Main objectives of testing

The main objectives of testing are to:

• evaluate work products such as requirements, code, and the system itself
• verify whether specified requirements are met
• validate whether the product is fit for purpose
• find defects and failures
• provide information for decision-making
• reduce quality risks
• build confidence in the quality of the product

Key takeaway: Testing is not just bug hunting. It is a structured activity that helps teams understand

quality, reduce risk, and make better decisions.

Self-check

• Is testing only about finding bugs?

https://www.youtube.com/watch?v=u6QfIXgjwGQ

Testing vs debugging

Testing and debugging are connected, but they are not the same.

Testing

Testing is the process of identifying defects, failures, and quality risks. Its purpose is to discover problems

and provide information about product quality.

Debugging

Debugging is the process of finding the cause of a defect, analyzing it, and fixing it. It is usually performed by developers.

Example

• A tester finds that the checkout total is incorrect when a discount is applied. This is testing.
• A developer investigates the calculation logic, finds the wrong formula, fixes the code, and checks the fix.

This is debugging.

Key takeaway: Testing shows that a problem exists. Debugging finds the cause and removes it.

Self-check

• Who usually performs testing?
• Who usually performs debugging?
• Why are these activities different?

How testing contributes to success

Software is part of daily life. People use it to pay bills, transfer money, communicate, study, travel, and work.

When software fails, the consequences can range from inconvenience to financial loss, reputational damage,

security issues, or even safety risks.

Testing contributes to success by:

• preventing important defects from reaching users
• helping teams understand product risks
• supporting better release decisions
• improving confidence in the product
• reducing the cost of fixing problems later

Cost of defects

In general, the later a defect is found, the more expensive it is to fix.

For example:

• a problem found in a requirement may take minutes to correct
• the same problem found after implementation may require rework from several team members
• the same problem found in production may affect users, support teams, reputation, and deadlines

This is why early testing matters.

Real-world impact

Software failures have caused:

• major financial losses in trading and payment systems
• privacy problems in communication platforms
• service outages in online products
• safety incidents in healthcare and industrial systems

Key takeaway: Testing helps teams catch important problems earlier, reduce business risk, and improve

product quality.

Self-check

• Why is early defect detection important?
• How can testing help a business succeed?

Errors, defects, failures, and root causes

These terms describe different parts of the same problem chain.

Error: a human mistake, such as misunderstanding a requirement or writing incorrect logic.

Defect: a flaw in code, documentation, or another work product caused by an error.

Failure: incorrect behavior observed when a defect is triggered during execution.

Root cause: the underlying reason why the problem happened in the first place.

Error → Defect → Failure

Example

A product manager gives an unclear requirement (possible root cause). A developer misunderstands it

(error). The wrong discount formula is implemented in the code (defect). The user sees the wrong total

during checkout (failure).

Why root cause matters

If teams only fix the visible defect but ignore the root cause, similar problems may happen again.

Common root causes include: