Exploring Software Testing

Software Testing

• Computer programs are designed and developed by human beings and hence are prone to errors.
• Unchecked, they can lead to a lot of problems, including social implications. 
• Testing the software becomes an essential part of the software development lifecycle.
• Carrying out the testing activities for projects has to be practiced with proper planning and must be implemented correctly.
• “Testing is the process of executing a program with the intention of finding errors.” – Myers
• “Testing can show the presence of bugs but never their absence.” – Dijkstra

Most Common Software Problems

• Incorrect calculation
• Incorrect data edits & ineffective data edits
• Incorrect matching and merging of data
• Data searches that yield incorrect results
• Incorrect processing of data relationship
• Incorrect coding/implementation of business rules
• Inadequate software performance
• Confusing or misleading data
• Software usability by end users & Obsolete Software
• Inconsistent processing
• Unreliable results or performance
• Inadequate support of business needs
• Incorrect or inadequate interfaces with other systems
• Inadequate performance and security controls Incorrect file handling

Need of Software Testing

• Executing a program with the intent of finding an error.
• To check if the system meets the requirements and be executed successfully in the Intended environment.
• To check if the system is “ Fit for purpose”.
• To check if the system does what it is expected to do.
• A good test case is one that has a probability of finding an as-yet-undiscovered error.
• A successful test is one that uncovers a yet undiscovered error.
• A good test is not redundant.
• A good test should be “best of breed”.
• A good test should neither be too simple nor too complex.

Types of Software Testing

1. Manual Testing

• Manual testing includes testing a software manually, i.e., without using any automated tool or any script.
• In this type, the tester takes over the role of an end-user and tests the software to identify any unexpected behavior or bug.
• There are different stages for manual testing such as unit testing, integration testing, system testing, and user acceptance testing.
• Testers use test plans, test cases, or test scenarios to test software to ensure the completeness of testing.
• Manual testing also includes exploratory testing, as testers explore the software to identify errors in it.

2. Automation Testing

• Automation testing, which is also known as Test Automation, is when the tester writes scripts and uses another software to test the product.
• This process involves the automation of a manual process.
• Automation Testing is used to re-run the test scenarios that were performed manually, quickly, and repeatedly.

Software Testing Methods

1. Black Box Testing

• Incorrect or missing functions, Interface errors, Errors in data structures or external database access, Performance errors, Initialization and termination errors
• Black box / Functional testing
  • Based on requirements and functionality
  • Not based on any knowledge of internal design or code
  • Covers all combined parts of a system
  • Tests are data-driven
• Black Box Testing method is applicable to the following levels of software testing:
  • Integration Testing
  • System Testing
  • Acceptance Testing
• Example: A tester, without knowledge of the internal structures of a website, tests the web pages by using a browser; providing inputs (clicks, keystrokes) and verifying the outputs against the expected outcome.

2. White Box Testing

• Knowledge of the internal program design and code required.
• Tests are based on coverage of code statements, branches, paths, conditions.
• Incorrect or missing functions, Interface errors, Errors in data structures or external database access, Performance errors, Initialization and termination errors
• White box testing / Structural testing
  • Based on the knowledge of the internal logic of an application's code
  • Based on the coverage of code statements, branches, paths, conditions
  • Tests are logically driven
• White Box Testing method is applicable to the following levels of software testing:
  • Unit Testing: For testing paths within a unit.
  • Integration Testing: For testing paths between units.
  • System Testing: For testing paths between subsystems.
• Example: A tester, usually a developer as well, studies the implementation code of a certain field on a webpage, determines all legal (valid and invalid) AND illegal inputs and verifies the outputs against the expected outcomes, which is also determined by studying the implementation

3. Grey-Box Testing

• It combines the concept of both Black box as well as white box testing.
• In Grey box testing, the inside of your product is partly known to the tester.
• This has partial access to data-structures residing internally for designing different test cases, but at the same time tests from a user's perspective or like a black-box tester.
• Grey box testing has its name grey because from a tester's eye, it's like a semi-transparent box and also combining the color of black and white gives the shades of grey.
• Main features:
  • test design is based on the data structures and algorithms knowledge
  • actual tests are conducted using the exposed interfaces
  • a tester can have access to the source code for test cases design
• Test design techniques based on grey box testing:
  • matrix testing
  • regression testing
  • orthogonal array testing
  • pattern testing

Levels of Software Testing

• Levels of testing include different methodologies that can be used while conducting software testing.
• The main levels of software testing are −
• Functional Testing
  • Unit Testing
  • Integration Testing
  • System Testing
  • Regression Testing
  • Acceptance Testing
  • Alpha Testing
  • Beta Testing
• Non-functional Testing
• Performance Testing
  • Load Testing
  • Stress Testing
• Usability Testing
• Security Testing
• Portability Testing