Principles of Testing and Analysis

 1) What : The quality process

Quality Process : Set of activities and responsibilities

• Focused primarily on ensuring adequate dependability.
• concerned with project schedule or with product usability.

The quality process provides a framework for

• selecting and arranging activities.
• considering interactions and trade-offs with other important goals.

Process Quality

• Repeatability, Timeliness, Cost.

Product Quality

• Internal Qualities: Reusability, Manageability, Maintainability, Modifiability.
• External Qualities: 
  - Dependability qualities : Availability, correctness, reliability, safety, robustness.
  - Usefulness qualities : Usability, Performance, Security, Portability, Interoperability.

2) Where : Focusing on problematic constructs and modules most likely to contain bugs.

• Floating points numbers:
  Inherently imprecise. The imprecision may lead to invalid comparisons
  Sequences of computations may lose precision.
  
  
• Pointers(C/ C++):
  Pointers referring to the wrong memory areas can corrupt data.
  Aliasing can make programs difficult to understand and change.
  
  
• Parallelism:
  Can result in subtle timing errors because of unforeseen interaction between parallel processes
  Can result in deadlock if synchronization is used incorrectly.
  
  
• Numeric Limits/Boundaries:
  Very large values for integers/floats
  Boundary values for relational expressions.
  
  
• Interrupts:
  Interrupts can cause a critical operation to be terminated and back make a program difficult to understand.
  Interrupts are comparable to goto statements.
  
  
• Complex boolean expression:
  Nested boolean operators can be difficult to understand.
  
  
• Casts and conversions between types:
  Especially numeric types : can lose precision or overflow

3) When : Performing testing as early and often as possible.
It involves V model

V Model:

It is a model of software development which pairs phases. Each phase on the left side of the V generates test planning for an accompanying phase on the right side.

Validation:

• Confirms that the software performs to the user's satisfaction.
• Assuring that the software system meets the user's needs.
• Answering "Are we building the right product?"

Verification: 

• Confirms that the software performs and conforms to its specification.
• Answering "Are we building the product right?"

4) Who : Structuring organization for effective testing.

5) How : Strategies for effective testing

• Scope of tests
  
• Purpose of tests
• Testing techniques
• Visibility : Observability, State exposure, Logging
• Repeatability
• Redundancy
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