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Advanced Material

Advanced Material. The following slides contain advanced material and are optional. Outline. Testing What is testing Unit testing Automatic testing. Program verification. Verification checks validity of a program by Testing (here, functional testing on class level) Proving Testing

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Advanced Material

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  1. Advanced Material The following slides contain advanced material and are optional.

  2. Outline • Testing • What is testing • Unit testing • Automatic testing

  3. Program verification • Verification checks validity of a program by • Testing (here, functional testing on class level) • Proving • Testing • Execute a program to check if it works • Verifies one particular execution of a program • Applicable to no/partial specification • Proving • Program is statically checked (not executed) • Verifies every possible execution • Needs complete specification

  4. Testing • Execute program • Manual testing • Unit testing • Automatic testing • If a test is successful: • The program works with exactly this input • The program could still fail with different input • If a test fails: • Bug found in program • A good test is a test that fails!

  5. Unit testing • Write test for a „unit“ of source code: • In object-oriented code, mostly per routine or class • Each test case has three steps • Prepare environment • Run test case • Evaluate output • Library support exists for all major languages

  6. Demo

  7. Automatic testing • Generate test cases automatically • Need a way to generate valid input data • Need a way to check validity of output data • Any ideas? • Input to a routine is valid if precondition is satisfied • Output of a routine is valid if postcondition is satisfied

  8. Automatic input generation • Create objects at random by • Calling a creation routine • Calling commands on the object • These objects can then be used to test a routine • Call routine with random input data (in case of basic types like integer) • Call routine with random objects, created as mentioned above

  9. Validate input • Check if randomly chosen objects satisfy precondition • If yes, this is a valid test case • If no, ignore this test case

  10. Evaluate output • For a valid test case, check if postcondition is satisfied • If yes, the test was successful • If no, there is a bug in the routine • Test also fails if • any exception happens during routine evaluation, e.g. Void-call or Precondition violation

  11. Demo

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