System testing in Testing Fundamentals - Full Explanation

Introduction

Imagine building a complex machine with many parts. You want to make sure the whole machine works well together before using it. System testing solves this problem by checking the entire software system as one complete unit.

Explanation

Purpose of System Testing

System testing checks the complete and integrated software to verify it meets the specified requirements. It ensures that all parts of the software work together correctly as a whole. This testing happens after unit and integration testing are done.

System testing validates the entire software system's behavior against requirements.

Types of System Testing

There are many types of system testing, such as functional testing, performance testing, security testing, and usability testing. Each type focuses on a different aspect of the system to ensure it works well under various conditions and meets user expectations.

System testing includes multiple testing types to cover all aspects of the software.

Environment for System Testing

System testing is performed in an environment that closely resembles the real production environment. This helps catch issues that might only appear when the software runs in conditions similar to actual use.

Testing in a realistic environment helps find real-world problems before release.

Difference from Other Testing Levels

Unlike unit testing, which tests small parts, and integration testing, which checks combined parts, system testing tests the entire system as one. It focuses on overall behavior rather than individual components.

System testing looks at the software as a whole, not just parts or connections.

Real World Analogy

Think of assembling a new car. After building each part and connecting them, you take the whole car for a test drive to see if everything works together smoothly. This final test drive is like system testing for software.

Purpose of System Testing → Taking the fully assembled car for a test drive to check overall performance.

Types of System Testing → Checking the car’s speed, safety features, fuel efficiency, and comfort during the test drive.

Environment for System Testing → Driving the car on roads and conditions similar to where it will be used.

Difference from Other Testing Levels → Testing the whole car instead of just individual parts like the engine or brakes.

Diagram

Diagram

┌───────────────┐
│   Unit Test   │
│ (Individual   │
│   parts)      │
└──────┬────────┘
       │
┌──────▼────────┐
│ Integration   │
│   Test        │
│ (Combined     │
│  parts)       │
└──────┬────────┘
       │
┌──────▼────────┐
│ System Test   │
│ (Whole system)│
└───────────────┘

This diagram shows the testing levels from unit testing to integration testing, and finally system testing of the whole software.

Key Facts

System Testing → Testing the complete and integrated software system to verify it meets requirements.

Functional Testing → A type of system testing that checks if software functions work as expected.

Performance Testing → System testing that measures how well software performs under load.

Testing Environment → The setup where system testing is performed, ideally similar to production.

Integration Testing → Testing combined parts of software before system testing.

Common Confusions

System testing is the same as integration testing.

System testing is the same as integration testing. System testing checks the entire software as a whole, while integration testing focuses on interactions between combined parts.

System testing can be done without a realistic environment.

System testing can be done without a realistic environment. System testing should be done in an environment close to real use to catch practical issues.

Summary

System testing checks the entire software system to ensure it meets all requirements.

It includes various types like functional and performance testing to cover different aspects.

System testing is done after unit and integration testing, in an environment similar to real use.

Practice

1. What is the main purpose of system testing in software development?

easy

A. To write code for new features

B. To test individual units or components separately

C. To test the complete software as a whole to verify it meets requirements

D. To deploy the software to users

Solution

1. Step 1: Understand system testing scope

   System testing tests the entire software system together, not parts separately.

2. Step 2: Compare options with system testing goal

   Only To test the complete software as a whole to verify it meets requirements describes testing the complete software to check requirements.

3. Final Answer:

   To test the complete software as a whole to verify it meets requirements -> Option C

4. Quick Check:

   System testing = whole software check [OK]

Hint: System testing checks the whole software, not parts [OK]

Common Mistakes:

• Confusing system testing with unit testing
• Thinking system testing is done before integration testing
• Believing system testing involves coding or deployment

2. Which of the following is the correct sequence of testing phases including system testing?

easy

A. Unit testing -> Integration testing -> System testing -> Acceptance testing

B. System testing -> Unit testing -> Integration testing -> Acceptance testing

C. Integration testing -> Unit testing -> System testing -> Acceptance testing

D. Acceptance testing -> System testing -> Integration testing -> Unit testing

Solution

1. Step 1: Recall testing order

   Testing starts with unit testing, then integration, then system, and finally acceptance testing.

2. Step 2: Match sequence with options

   Only Unit testing -> Integration testing -> System testing -> Acceptance testing matches the correct order.

3. Final Answer:

   Unit testing -> Integration testing -> System testing -> Acceptance testing -> Option A

4. Quick Check:

   Testing order = Unit -> Integration -> System -> Acceptance [OK]

Hint: Remember testing flows from small parts to whole system [OK]

Common Mistakes:

• Mixing up the order of integration and system testing
• Thinking system testing happens before unit testing
• Confusing acceptance testing with system testing

3. Consider this test scenario during system testing:
Test if the login page accepts valid username and password and redirects to the dashboard.
What is the expected result if the system works correctly?

medium

A. The login page shows an error message for valid credentials

B. The user is redirected to the dashboard after successful login

C. The system crashes after submitting credentials

D. The login page reloads without any message

Solution

1. Step 1: Understand the test scenario

   The test checks if valid login credentials allow access to the dashboard.

2. Step 2: Identify correct expected behavior

   On valid login, the user should be redirected to the dashboard, which is The user is redirected to the dashboard after successful login.

3. Final Answer:

   The user is redirected to the dashboard after successful login -> Option B

4. Quick Check:

   Valid login -> dashboard redirect [OK]

Hint: Valid login should lead to dashboard, not errors [OK]

Common Mistakes:

• Expecting error messages for valid inputs
• Confusing page reload with successful login
• Ignoring redirection behavior in system testing

4. During system testing, a tester finds that the software crashes when clicking the 'Submit' button on a form. What should the tester do next?

medium

A. Ignore the crash and continue testing other features

B. Restart the software and try again without reporting

C. Fix the code themselves immediately

D. Report the defect with steps to reproduce and environment details

Solution

1. Step 1: Identify correct tester action

   Testers should report defects with clear reproduction steps and environment info.

2. Step 2: Evaluate options

   Only Report the defect with steps to reproduce and environment details describes proper defect reporting. Others ignore or bypass the issue.

3. Final Answer:

   Report the defect with steps to reproduce and environment details -> Option D

4. Quick Check:

   Tester reports bugs properly [OK]

Hint: Always report bugs with clear details, never ignore [OK]

Common Mistakes:

• Ignoring critical crashes during testing
• Trying to fix code without developer role
• Not providing reproduction steps in bug reports

5. A software system has passed unit and integration tests. During system testing, it fails to handle simultaneous user logins correctly, causing data conflicts. What is the best approach to solve this issue?

hard

A. Add concurrency control mechanisms and retest the system

B. Skip system testing and release the software anyway

C. Only fix the user interface without changing backend logic

D. Reduce the number of users allowed to login simultaneously

Solution

1. Step 1: Analyze the problem cause

   Data conflicts on simultaneous logins indicate concurrency issues in backend logic.

2. Step 2: Choose appropriate fix

   Adding concurrency control (like locks or transactions) addresses the root cause and requires retesting.

3. Step 3: Evaluate other options

   Skipping testing or only fixing UI won't solve backend conflicts; limiting users is impractical.

4. Final Answer:

   Add concurrency control mechanisms and retest the system -> Option A

5. Quick Check:

   Fix concurrency bugs before release [OK]

Hint: Fix backend concurrency issues, then retest system [OK]

Common Mistakes:

• Ignoring concurrency problems during system testing
• Trying to fix only UI for backend issues
• Releasing software without fixing critical bugs