COEN 286: Software Quality Assurance and Testing -- fall, 2001

Testing Objectives

Prof. John Noll

Santa Clara University

1. Objectives

1.1 What can be achieved?

• Complete testing is not possible.
• Testing ``completely'' means that there are no more undiscovered errors. Not possible:
  • too many inputs;
  • too many paths;
  • too complex ui.

1.2 The purpose of testing

The purpose of testing is to find problems.

• ``A test that reveals a problem is a success.''
• ``A test that did not reveal a problem was a waste of time.'' But, it does show that the specific problem is absent. Not a complete waste of time.

The purpose of finding problems is to get them fixed.

2. Test types

2.1 Verification

• Inspection of specifications.
• Is the only kind of ``testing'' possible during early phases.
• Can be done by machines for certain kinds of inspection.

2.2 White box testing

Testing by execution using knowledge or design or implementation.

Coverage

    
      if (A > B && C == 0) {
         C = 1;
      }
      D = A / D;
  

• statement: all statements are executed at least once.

  This is harder than it sounds: defensive programming makes some code hard to get to.

  ---

          if (f = fopen(path)) {
             perror("fopen");
          }
     
  

  ---

• branch: all branches are taken.
• condition: all conditions on branches are evaluated true and false.

  Only this will catch bug above.

• cyclomatic.
• path: all paths are tested.

2.3 Black Box Testing

Functional testing of program features as specified.