cs 211 juint

• The goal of testing is to gain assurance about the quality of your programs
• The testing you do for your class assignments is more likely to be debugging oriented
• Testing


  • Running a program on various inputs
  • Any human or computer assessment of quality
  • Evaluations before writing code
• The earlier we find a problem, the easier and cheaper it is to fix
• Maintenance activities consume 70-90% of the total cost of software
• Some software engineering approaches advocate writing test cases BEFORE you even write any code
• The earlier you find a defect, the cheaper it is to fix
• Modern day testing is preventive
• Software maintenance


  • Modifying a program after it has been put into use
  • Maintenance does not normally involve major changes to the system's architecture
  • Changes are implemented by modifying existing components and adding new components to the system
  • Maintenance requires program understanding
• When the transition from development to evolution is not seamless, the process of changing the software after delivery is often called software maintenance
• Importance of maintenance


  • Organizations have huge investments in their software systems - they are critical business assets
  • To maintain the value of these assets to the business, they must be changed and updated
  • Much of the software budget in large companies is for modifying existing software
• We cannot avoid changing software
• A key problem for organizations is implementing and managing change to their existing software systems
• Review


  • A meeting in which several people examine a design document or section of code
  • It is a common and effective form of human-based testing
  • Presenting a design or code to others makes us think more carefully about it and provides an outside perspective
• Test case


  • A set of input and user actions, coupled with the expected results
  • Often test cases are organized formally into test suites which are stored and reused as needed (like JUnit)
  • For medium and large systems, testing must be a carefully managed process
  • Many organizations have a separate Quality Assurance (QA) department to lead testing efforts
• Defect testing


  • The execution of test cases to find errors
  • The act of fixing an error may introduce new errors
  • After fixing a set of errors we should perform regression testing - running previous test suites to ensure new errors haven't been introduced
• It is not possible (in general) to create test cases for all possible input and user actions
• Black-box testing


  • Test cases are developed without considering the internal logic
  • They are based on the input and expected output
  • Input can be organized into equivalence categories
  • Two input values in the same equivalence category would produce similar results
  • A good test suite will cover all equivalence categories and focus on the boundaries between categories
• White-box testing


  • Focuses on the internal structure of the code
  • The goal is to ensure that every path through the code is tested
  • Paths through the code are governed by any conditional or looping statements in a program
  • A good testing effort will include both black-box and white-box tests
• Defining what correctness means is a tough problem
• JUnit


  • Unit testing for Java
  • Provides individual test cases that target specific units of code, usually a specific method or a specific branch of code
  • Offers a form of regression testing: make a few changes, re-run all JUnit tests to check if we broke previously-tested code
• JUnit test methods


  • assertTrue(boolExpr)
  • assertEquals(Object expected, Object actual)
  • assertNotNull(Object o)
• JUnit integrates very well with IDEs (also works on command-line)
• The goal of testing is to gain assurance about the quality of your programs
• The testing you do for your class assignments is more likely to be debugging oriented
• Testing


  • Running a program on various inputs
  • Any human or computer assessment of quality
  • Evaluations before writing code
• The earlier we find a problem, the easier and cheaper it is to fix
• Maintenance activities consume 70-90% of the total cost of software
• Some software engineering approaches advocate writing test cases BEFORE you even write any code
• The earlier you find a defect, the cheaper it is to fix
• Modern day testing is preventive
• Software maintenance


  • Modifying a program after it has been put into use
  • Maintenance does not normally involve major changes to the system's architecture
  • Changes are implemented by modifying existing components and adding new components to the system
  • Maintenance requires program understanding
• Organizations have huge investments in their software systems - they are critical business assets
• Much of the software budget in large companies is for modifying existing software
• We cannot avoid changing software
• Reasons for software changes

  • New requirements emerge when the software is used
  • The business environment changes
  • Faults must be repaired
  • New computers and equipment is added to the system
  • The performance or reliability of the system may have to be improved
• A key problem for organizations is implementing and managing change to their existing software systems
• Review

  • A meeting in which several people examine a design document or section of code
  • It is a common and effective form of human-based testing
  • Presenting a design or code to others makes us think more carefully about it and provides an outside perspective
• Test case


  • A set of input and user actions, coupled with the expected results
  • Often test cases are organized formally into test suites which are stored and reused as needed (like JUnit)
• For medium and large systems, testing must be a carefully managed process