Implementation Phase

1
Implementation Phase

• Programming-in-the-many
• Most real-life products are too large to be
  implemented by one programmer
• Implemented by a team
• Working at the same time on different components
  of the product
• Testing/Module reuse/CASE tool

2
Implementation Phase

• Fourth Generation Languages (4GL)
• 1GL a binary machine code
• 2GL assemblers (1940-50s)
• 3GL high level languages (FORTRAN, ALGOL 60,
  COBOL, etc)
• 4GL DB2, Oracle, PowerBuilder, SQL (1970s)
• shorter (30-50 MCI),
• easier to maintain/use,
• CASE Tool more productive, cost effective

3
Implementation Phase

• Good Programming Practice
• Use of consistent and meaningful identifier names
• Self-documenting code/documentation
• Use of Parameters
• Code layout for increased readability
• Coding style for incremental programming (Module
  reuse)

4
Implementation Phase (Types of Errors)

• Syntax Errors
• Logic/Algorithm Errors
• Branching too soon/ too late
• Testing the wrong condition
• Initialization errors
• Data type mismatch
• Incorrect formula or computation
• Documentation Errors - mismatch between
  documentation and code leads to difficulties
  especially during maintenance

5
Implementation Phase (Types of Errors)

• Capacity Errors - system performance degradation
  at capacity
• Hardware Errors
• Throughput/performance Errors
• Computation/precision Errors
• Stress/overload Errors
• Recovery Errors - error handling faults
• Standards/Procedures - created/introduced as the
  system is tested modified

6
Implementation Phase (Testing Principles)

• Process of finding errors
• Impossible to completely test software
• Creativity and hard work required
• Error prevention
• Independent testers

7
Implementation Phase (Testing Steps)

• Select what is to be measured by the test and
  decide how the code will be tested
• Develop the test cases for the code and
  determine the correct results for the test cases
• Execute the test cases and compare the actual
  results with the expected results
• Regression Testing -If errors are discovered,
  earlier test cases should be re-executed.

8
Black-box Testing

• focused on inputs and outputs of a module
  equivalence partitioning, equivalence class
  contains similar test cases (reduce redundancy)
• equivalence Testing Boundary Value Analysis
• If valid input is a range of values, there are a
  minimum of three equivalence classes one below
  the range, one within the range, and one above
  the range
• If valid input is a value from a discrete set of
  values, there are two equivalence classes valid,
  discrete values and any other input values.

9
Black-box Testing

• Functional Testing
• demonstrate that all functions work according to
  requirements and specification document
• determining all the functions of the module
• test data are devised to test each function
  separately
• If the module consists of a hierarchy of
  lower-level functions, functional testing
  proceeds recursively.
• OSBERT OGLES BY CASE STUDY (13.16)