6. Testing and running solutions

6. Testing and running solutions

1. errors

   • syntax- error used in the programming language- e.g: missing braces, no semi-colon, missing parts of constructs
   • logical- caused by the mistakes in the design of the program, code will run but will not give the right results
   • run-time- happens while the program is running, syntax is fine but when run an error is found due to mistakes in the algorithm or an external reason- e.g.: out of memory, divide by 0...

2. testing

   • black box test data can be:
     • NORMAL- very surely and completely within the range (should be accepted)- makes sure that the program performs properly,
     • BORDERLINE- on the border of range (v. important)- most errors are when borderline data is not accepted,
     • INVALID- outside the range (should be rejected), should check all data to make sure program works properly
   • testing strategies:
     • BLACK BOX: inputs tested to see if they produce the outputs that should be, done by customers, all parts of test data is tested
       • What is done: requirements and specifications of the system examined, data checked to see if expected outputs are git, test cases created and executed, outputs compared, defects fixed and retested
       • Finds: incorrect/ missing functions, interface errors, data structure errors, performance errors, initialisation and termination
       • Advantages: does not need to know coding, less bias (third party), test cases can be tested as soon as spec is produced
       • Disadvantages: way program works is not considered, test cases are difficult to design, time consuming to test every input, white box has to still be carried out
     • WHITE BOX: testers test each line of code for logic and accuracy, normally tests extremes, done manually or debugging software
       • Advantages: helps optimize the code, can test effectively as it is easy to find the best data to use, tested by programmer so they know the program well
       • Disadvantages: Uses specific programming knowledge, Only works if the programmer know what the program actually does, Does not account for errors that are created from omission
     • ACCEPTANCE: done when the software is complete, programmer has to prove that the program fits all of the customers specification, can be done as alpha or beta testing
     • ALPHA: done in the company where employees who did not produce software test it
       • Advantages: uses both black box and white box testing, problems are sorted immediately
       • Disadvantages: doesn't check reliability robustness and security, requires testing environment, software might not be complete so might still contain errors
     • BETA: privileged customers test the software and give back constructive criticisms
       • Advantages: checks reliability robustness and security, can be done anywhere, software virtually complete but might sill have bugs
       • Disadvantages:uses only black box testing, problems implemented in future versions of software

3. dry runs(trace tables)

   • put each variable and track the value of each variable

4. debugging tools

   • translator diagnostics- points out if there are any errors in the code by saying which part of which line is wrong- error messages - syntax error
   • Break point- tell it to pause at a certain point in the code- can go through line by line after- can trace variables in a trace table- double click to add it- logical or run time
   • stepping- going through the code line by line- can do it at your speed- check variables- logical or run time
   • variable checks- trace tables- look at variables and their value at each point- can look at patterns to find errors- logical and run time error

5. purpose of an installation routine

   • Copy program from CD to computer
   • Copy any data files from the CD to computer
   • Copy and registered any library routines which are needed from CD to computer
   • Check for any dependencies
   • Check for space
   • Check for compatibility
   • Register the program in the computer
   • Enable the program to be uninstalled later
   • Initial user configuration is saved in a file
   • Provide an icon or shortcut so that the program can be run easily
   • Programs may need extracting from a compressed file

Bilder und Dateien der Mindmap