Clean-up and Testing and Debugging

• You frequently see

  • 
      bool badData;
    
      ...
    
      badData = (0.0 == height); 

  • This is equivalent to

  •   bool badData;
    
      if (0.0 == height) {
          badData = true;
      } else {
          badData = false;
      } 

  • Due to operator precedence, badData = 0.0== height; works as well
• Short circuit evaluation
  • In a complex boolean expression, it is sometimes not necessary to evaluate the entire expression to find the final value.
    • true or anything = true
    • false and anything = false
  • so in the expression x < 3 and ... if x is not less than 3, the expression will be false.
  • in the expression x < 3 or ... if x is less than 3, the expression will be true.
  • In such cases, evaluation will stop as soon as the value of the expression can be determined.
  • This becomes important later when we use arrays and linked lists.
  • So REMEMBER the concept.
• Testing
  • If our program has branches, we need to make sure that we evaluate each of the paths through our program.
  • For the programs we are writing now, this is easier
  • For later program, this becomes more difficult or even impossible.
  • This is called code coverage or white box testing because we look at the code to decide what to test.
  • In data coverage or black box testing we do not look at the code but consider the classes of data.
  • Both of these are very difficult if not impossible, so a mixture is used.
    • Look at the code to see what decisions are made
    • Use this to break the input data into multiple classes
    • Develop test data for each class, along with border data.
  • A Test Plan is a document that specifies how a program will be tested.
  • For your current program my test plan might include

    Case	Input Values	Expected Output	Observed Output
    Misspelled Name	mars, Mxrs	New Weight: unknown
    Correct Name	Check for each planet, weight = 100	New Weight: xx.xxxx, check against table
    Floating point round off	Earth, weight 1.23456	New Weight: 1.2346

  • Note, this is a black box test, based on the data.
  • You should read chapter 5.