Program Debugging

There are 3 different approaches to debugging and they includes:

• Induction Approach
• Deduction Approach
• Intuition Approach

Difficulties in Program Walkthrough

As testing should be done by someone else, some difficulties of a Program Walkthrough includes:

• cannot depend on human eyes
  
• Programmers would be reluctant
  
• difficulties in inviting external party
  
• resources

Structural Testing in SDLC

Continuing on the Structural Testing:

• More powerful form of test is Path Coverage
  
• This strategy ensures that all statements in the program are executed at least once and conditional statements are tested for both true and false cases
  
• The starting point is to derive a program flow graph
  
• A flow graph consists of nodes representing decisions and edges showing flow of control
  
• Tester must not be seduced into thinking that such testing is adequate
  
• Cyclomatic complexity is a measure of the program's control complexity. The data complexity is not taken into account
  
• Program fragments which are equivalent in function may not have the same cyclomatic complexities
  
• It is generally true that the # of paths through a program is proportional to its size. Thus, as modules are integrated into systems, it is unfeasible to use structural testing techniques.

What is Structural Testing

Structural Testing includes:

• Cover structure, quality and style.
  
  
• Implementation based.
  
  
• Best done by programmer.
  
  
• Not aiming at testing functions or detecting missing functions.
  
  
• The tester analyses the code and use knowledge about the structure of a component to derive the test data.
  
  
• Simplest form of testing includes:
  - Statement coverage
  - Branch coverage

Cause-effect Analysis

Another analysis you should consider in Functional Testing is Cause-effect Analysis. This includes:

• Even when a program operates successfully for individual test inputs, combinations of these inputs may detect program errors.
  
  
• Involves examining the output and analysing to see if combinations of input partitions always cause outputs in the same output partition to be producted.
  
  
• The causes of these effects used as test cases.
  

Boundary Value Analysis

In Functional Testing, one of the consideration is Boundary Value Analysis. This includes:

• Input conditions are 'edges' of equivalence class.
  
  
• Values like above and below range, minimum and maximum number and up to the array limit.

What is Equivanlence Testing

Equivalence Testing is:

• Input conditions are partitioned into Equivalence Classes.
  
  
• Classes like specific numeric value, range of values and set of related values.

Example:

A database state that the product must be able to handle any no of records from 0 to 100,000.

Art of Testing in SDLC

Art of testing is to set up a small, manageable set of test cases in such a way as to maximize the chances of detecting a fault while minimizing the chances of wasting a test case by having the same fault detected by more than one test case.

The technique use is Equivalence Testing + Boundary Vaule Analysis + Cost Effect Analysis

Functional Testing - SDLC

What is Functional Testing?

• It is function oriented.
  
  
• Test cases prepared by looking at logic from outside just as though it was a black box.
  
  
• Concentration on the verification process.
  
  

So what should be considered in this functional testing black box?

• Under waht conditions would we not perform the test?
  
  
• What should we know and need to know about the input and output?
  
  
• What can we state about our assumptions and expectations?
  
  
• How much must we know about the intended use of the system?
  
  
• How important are the various attributes and how much can we trade one off again another?
  
  
• What is the one factor against wich all others can be judged?

Module Testing

For testing, there are 2 ways of systematically contructing test data to test a module. These include:

• Functional Test
  To test according to the specification.
  
  
• Structural Test
  Testing on the code.