2. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 1 Software Engineering: A Practitioner’s Approach, 6/e Chapter 14 Software Testing Techniques Software Engineering: A Practitioner’s Approach, 6/e Chapter 14 Software Testing Techniques copyright © 1996, 2001, 2005 R.S. Pressman & Associates, Inc. For University Use Only May be reproduced ONLY for student use at the university level when used in conjunction with Software Engineering: A Practitioner's Approach. Any other reproduction or use is expressly prohibited.

3. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 2 What is a “Good” Test? A good test has a high probability of finding an error A good test has a high probability of finding an error A good test is not redundant. A good test is not redundant. A good test should be “best of breed” A good test should be “best of breed” A good test should be neither too simple nor too complex A good test should be neither too simple nor too complex

4. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 3 Test Case Design "Bugs lurk in corners and congregate at boundaries..." Boris Beizer OBJECTIVE CRITERIA CONSTRAINT to uncover errors in a complete manner with a minimum of effort and time

5. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 4 Software Testing Methods Strategies white-box methods black-box methods

6. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 5 White-Box Testing... our goal is to ensure that all statements and conditions have been executed at least once...

7. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 6 Exhaustive Testing loop < 20 X There are 10 possible paths! If we execute one test per millisecond, it would take 3,170 years to test this program!! 14

8. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 7 Selective Testing loop < 20 X Selected path

9. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 8 Why Cover? logic errors and incorrect assumptions are inversely proportional to a path's execution probability we often believe believe that a path is not that a path is not likely to be executed; in fact, reality is often counter intuitive typographical errors are random; it's likely that untested paths will contain some

10. 4.4 Basis Path Testing White-box testing by McCabe in 1976 White-box testing by McCabe in 1976 Derive a logical complexity of the design Derive a logical complexity of the design Guide to define a basis set of execution path Guide to define a basis set of execution path Guarantee to execute each statement at least once. Guarantee to execute each statement at least once. Flow graph Flow graph Nodes – statements Nodes – statements Predicate nodes – conditions Predicate nodes – conditions Compound conditions need to be separated. Compound conditions need to be separated. Edges – flow of control Edges – flow of control Each edge must terminate at a node Each edge must terminate at a node These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 9

11. Basis Path Testing Control Structure – Flow Graph These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 10 sequence while If-then-else caseDo-until

12. 1 2 3 6 78 4 5 9 10 11 1 2,3 6 78 9 10 11 4,5 Node Edge R3 R2 R1 R4 Region Basis Path Testing Flow Graph

13. Basis Path Testing Independent Program Paths Independent path: a path that includes at least one edge that is not covered by other paths. Independent path: a path that includes at least one edge that is not covered by other paths. Basis set: a set of independent paths that guarantees that when they are executed, every statement in the program is executed at least one time. Basis set: a set of independent paths that guarantees that when they are executed, every statement in the program is executed at least one time. There may be more than one basis set. There may be more than one basis set. How many independent paths may exist in a program? How many independent paths may exist in a program? Cyclomatic complexity Cyclomatic complexity A measure of design complexity of a module A measure of design complexity of a module Upper bound for the number of independent paths in a basis set. Upper bound for the number of independent paths in a basis set. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 12

14. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 13 Basis Path Testing Cyclomatic Complexity A number of industry studies have indicated that the higher V(G), the higher the probability or errors. V(G) modules modules in this range are more error prone

15.  Number of regions The flow graph has 4 regions The flow graph has 4 regions  V(G) = E – N + 2 E : Number of flow graph edges E : Number of flow graph edges N : Number of flow graph nodes N : Number of flow graph nodes V(G) = 11 edges – 9 nodes + 2 = 4 V(G) = 11 edges – 9 nodes + 2 = 4  V(G) = P + 1 P : # of simple predicate nodes P : # of simple predicate nodes V(G) = 3 predicate nodes + 1 = 4 V(G) = 3 predicate nodes + 1 = 4 Basis Path Testing Cyclomatic Complexity 1 2,3 6 78 9 10 11 4,5 R3 R2 R1 R4

16. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 15 Basis Path Testing Cyclomatic Complexity Three ways to compute the cyclomatic complexity: 1. number of simple decisions + 1 2. number of enclosed areas + 1 In this case, V(G) = 4 3. # of edges - # of nodes + 2

17. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 16 Basis Path Testing Deriving Independent Paths Next, we derive the independent paths: Since V(G) = 4, there are four paths Path 1: 1,2,3,6,7,8 Path 2: 1,2,3,5,7,8 Path 3: 1,2,4,7,8 Path 4: 1,2,4,7,2,4,...7,8 Finally, we derive test cases to exercise these paths. 1 2 3 4 56 7 8

18. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 17 Control Structure Testing Condition testing — a test case design method that exercises the logical conditions contained in a program module Condition testing — a test case design method that exercises the logical conditions contained in a program module Data flow testing — selects test paths of a program according to the locations of definitions and uses of variables in the program Data flow testing — selects test paths of a program according to the locations of definitions and uses of variables in the program

19. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 18 Loop Testing NestedLoops Concatenated Loops Loops Unstructured Loops Simpleloop

20. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 19 Loop Testing: Simple Loops Minimum conditions—Simple Loops 1. skip the loop entirely 2. only one pass through the loop 3. two passes through the loop 4. m passes through the loop m < n 5. (n-1), n, and (n+1) passes through the loop where n is the maximum number of allowable passes

21. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 20 Loop Testing: Nested Loops Start at the innermost loop. Set all outer loops to their minimum iteration parameter values. Test the min+1, typical, max-1 and max for the innermost loop, while holding the outer loops at their minimum values. Move out one loop and set it up as in step 2, holding all other loops at typical values. Continue this step until the outermost loop has been tested. If the loops are independent of one another then treat each as a simple loop then treat each as a simple loop else* treat as nested loops else* treat as nested loops endif* for example, the final loop counter value of loop 1 is used to initialize loop 2. Nested Loops Concatenated Loops

22. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 21 Black-Box Testing requirements events input output

23. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 22 Black-Box Testing How is functional validity tested? How is functional validity tested? How is system behavior and performance tested? How is system behavior and performance tested? What classes of input will make good test cases? What classes of input will make good test cases? Is the system particularly sensitive to certain input values? Is the system particularly sensitive to certain input values? How are the boundaries of a data class isolated? How are the boundaries of a data class isolated? What data rates and data volume can the system tolerate? What data rates and data volume can the system tolerate? What effect will specific combinations of data have on system operation? What effect will specific combinations of data have on system operation?

24. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 23 Graph-Based Methods To understand the objects that are modeled in software and the relationships that connect these objects In this context, we consider the term “objects” in the broadest possible context. It encompasses data objects, traditional components (modules), and object-oriented elements of computer software.

25. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 24 Equivalence Partitioning userqueries mousepicks outputformats prompts FKinput data

26. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 25 Sample Equivalence Classes user supplied commands responses to system prompts file names computational data physical parameters physical parameters bounding values bounding values initiation values initiation values output data formatting responses to error messages graphical data (e.g., mouse picks) data outside bounds of the program physically impossible data proper value supplied in wrong place Valid data Invalid data

27. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 26 Boundary Value Analysis userqueries mousepicks outputformats prompts FKinput data outputdomain input domain

28. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 27 Comparison Testing Used only in situations in which the reliability of software is absolutely critical (e.g., human-rated systems) Used only in situations in which the reliability of software is absolutely critical (e.g., human-rated systems) Separate software engineering teams develop independent versions of an application using the same specification Separate software engineering teams develop independent versions of an application using the same specification Each version can be tested with the same test data to ensure that all provide identical output Each version can be tested with the same test data to ensure that all provide identical output Then all versions are executed in parallel with real-time comparison of results to ensure consistency Then all versions are executed in parallel with real-time comparison of results to ensure consistency

29. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 28 OOT—Test Case Design Berard [BER93] proposes the following approach: 1.Each test case should be uniquely identified and should be explicitly associated with the class to be tested, 2.The purpose of the test should be stated, 3.A list of testing steps should be developed for each test and should contain [BER94]: a.a list of specified states for the object that is to be tested b.a list of messages and operations that will be exercised as a consequence of the test c.a list of exceptions that may occur as the object is tested d.a list of external conditions (i.e., changes in the environment external to the software that must exist in order to properly conduct the test) e.supplementary information that will aid in understanding or implementing the test.

30. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 29 Testing Methods Fault-based testing Fault-based testing The tester looks for plausible faults (i.e., aspects of the implementation of the system that may result in defects). To determine whether these faults exist, test cases are designed to exercise the design or code. The tester looks for plausible faults (i.e., aspects of the implementation of the system that may result in defects). To determine whether these faults exist, test cases are designed to exercise the design or code. Class Testing and the Class Hierarchy Class Testing and the Class Hierarchy Inheritance does not obviate the need for thorough testing of all derived classes. In fact, it can actually complicate the testing process. Inheritance does not obviate the need for thorough testing of all derived classes. In fact, it can actually complicate the testing process. Scenario-Based Test Design Scenario-Based Test Design Scenario-based testing concentrates on what the user does, not what the product does. This means capturing the tasks (via use-cases) that the user has to perform, then applying them and their variants as tests. Scenario-based testing concentrates on what the user does, not what the product does. This means capturing the tasks (via use-cases) that the user has to perform, then applying them and their variants as tests.

31. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 30 OOT Methods: Random Testing Random testing Random testing identify operations applicable to a class identify operations applicable to a class define constraints on their use define constraints on their use identify a minimum test sequence identify a minimum test sequence an operation sequence that defines the minimum life history of the class (object) an operation sequence that defines the minimum life history of the class (object) generate a variety of random (but valid) test sequences generate a variety of random (but valid) test sequences exercise other (more complex) class instance life histories exercise other (more complex) class instance life histories

32. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 31 OOT Methods: Partition Testing Partition Testing Partition Testing reduces the number of test cases required to test a class in much the same way as equivalence partitioning for conventional software reduces the number of test cases required to test a class in much the same way as equivalence partitioning for conventional software state-based partitioning state-based partitioning categorize and test operations based on their ability to change the state of a class categorize and test operations based on their ability to change the state of a class attribute-based partitioning attribute-based partitioning categorize and test operations based on the attributes that they use categorize and test operations based on the attributes that they use category-based partitioning category-based partitioning categorize and test operations based on the generic function each performs categorize and test operations based on the generic function each performs

33. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 32 OOT Methods: Inter-Class Testing Inter-class testing Inter-class testing For each client class, use the list of class operators to generate a series of random test sequences. The operators will send messages to other server classes. For each client class, use the list of class operators to generate a series of random test sequences. The operators will send messages to other server classes. For each message that is generated, determine the collaborator class and the corresponding operator in the server object. For each message that is generated, determine the collaborator class and the corresponding operator in the server object. For each operator in the server object (that has been invoked by messages sent from the client object), determine the messages that it transmits. For each operator in the server object (that has been invoked by messages sent from the client object), determine the messages that it transmits. For each of the messages, determine the next level of operators that are invoked and incorporate these into the test sequence For each of the messages, determine the next level of operators that are invoked and incorporate these into the test sequence

34. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 33 OOT Methods: Behavior Testing Accout { Accout { Open() Open() Setup() Setup() Deposit() Deposit() Withdraw() Withdraw() Balance() Balance() Summarize() Summarize() Creditlimit() Creditlimit() Close() Close()}

35. OOT Methods: Behavior Testing These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 34 Test cases cover all states Test cases cover all states Testcase 1 Testcase 1 Open,setup,deposit(initial),withdraw(final)close. Open,setup,deposit(initial),withdraw(final)close. Testcase 2 Testcase 2 Open,setup,deposit(initial),deposit, withdraw, withdraw(final)close. Open,setup,deposit(initial),deposit, withdraw, withdraw(final)close. Partition Testing Partition Testing Operations that cause state changes Operations that cause state changes Operations that cause no state change Operations that cause no state change

36. These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 35 Testing Patterns Pattern name: pair testing Abstract: A process-oriented pattern, pair testing describes a technique that is analogous to pair programming (Chapter 4) in which two testers work together to design and execute a series of tests that can be applied to unit, integration or validation testing activities. Pattern name: scenario testing Abstract: Once unit and integration tests have been conducted, there is a need to determine whether the software will perform in a manner that satisfies users. The scenario testing pattern describes a technique for exercising the software from the user’s point of view. A failure at this level indicates that the software has failed to meet a user visible requirement. [KAN01]