Levels of Testing

 The Levels of Testing:-

1. Unit Testing

• Testing individual small parts (functions or modules)
• Done by developers

Example: Test only login function

2. Integration Testing

• Testing combined modules together
• Checks data flow between modules

Example: Login module + Database connection

Basic Approaches of Integration Testing

1.Top-Down Approach

• Testing starts from top module to lower modules
• Uses stubs for lower modules
• Main functionality tested early

2. Bottom-Up Approach

• Testing starts from lower modules to top modules
• Uses drivers to test lower modules
• Core logic tested first

3. Big Bang Approach

• All modules integrated at once
• No stubs or drivers used
• Difficult to find exact bug location

4. Critical Path Approach

• Test most important user flow first
• Focus on business-critical features
• Reduces major business risk

Simple Comparison

• Approach Starts From              Uses                          Best For
• Top-Down Top module             Stubs                          Checking main flow early
• Bottom-Up Lower modules     Drivers                  Testing core logic first
• Big Bang         All modules             None                          Small projects
• Critical Path Important flow     Focus testing          Business-critical apps

3. System Testing

• Testing the complete application
• Done by testing team

Example: Test full online shopping website

4. User Acceptance Testing (UAT)

• Testing by end users or clients
• Checks if software meets business needs

Example: Client checks if website works as per requirement

Types of User Acceptance Testing (UAT)

1. Alpha Testing

• Done by internal team at company site
• Performed before release

Example: Company staff test new shopping app

2. Beta Testing

• Done by real users in real environment
• Performed after alpha testing

Example: Limited users test new mobile app before official launch

One Line:
Alpha is internal testing, Beta is external testing.