Chapter 11: Integrationand System Testing

Transcription

1 Object-Oriented Software Engineering Using UML, Patterns, and Java Chapter 11: Integrationand System Testing Integration Testing Strategy The entire system is viewed as a collection of subsystems (sets of classes) determined during the system and object design. The order in which the subsystems are selected for testing and integration determines the testing strategy Big bang integration (Nonincremental) Bottom up integration Top down integration Sandwich testing Variations of the above For the selection use the system decomposition from the System Design Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 2

2 Using the Bridge Pattern to enable early Integration Testing Use the bridge pattern to provide multiple implementations under the same interface. Interface to a component that is incomplete, not yet known or unavailable during testing VIP Seat Interface (in Vehicle Subsystem) Seat Implementation Stub Code Simulated Seat (SA/RT) Real Seat Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 3 Example: Three Layer Call Hierarchy A Layer I B C D Layer II E F G Layer III Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 4

3 Integration Testing: Big-Bang Approach Unit Test A Unit Test B Unit Test C Unit Test D Unit Test E Don t try this! System Test Unit Test F Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 5 Bottom-up Testing Strategy The subsystem in the lowest layer of the call hierarchy are tested individually Then the next subsystems are tested that call the previously tested subsystems This is done repeatedly until all subsystems are included in the testing Special program needed to do the testing, Test Driver: A routine that calls a subsystem and passes a test case to it SeatDriver (simulates VIP) Seat Interface (in Vehicle Subsystem) Seat Implementation Stub Code Simulated Seat (SA/RT) Real Seat Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 6

4 Bottom-up Integration A Layer I B C D Layer II Test E E F G Layer III Test B, E, F Test F Test C Test A, B, C, D, E, F, G Test G Test D,G Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 7 Pros and Cons of bottom up integration testing Bad for functionally decomposed systems: Tests the most important subsystem (UI) last Useful for integrating the following systems Object-oriented systems real-time systems systems with strict performance requirements Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 8

5 Top-down Testing Strategy Test the top layer or the controlling subsystem first Then combine all the subsystems that are called by the tested subsystems and test the resulting collection of subsystems Do this until all subsystems are incorporated into the test Special program is needed to do the testing, Test stub : A program or a method that simulates the activity of a missing subsystem by answering to the calling sequence of the calling subsystem and returning back fake data. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 9 Top-down Integration Testing A Layer I B C D Layer II E F G Layer III Test A Test A, B, C, D Test A, B, C, D, E, F, G Layer I Layer I + II All Layers Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 10

6 Pros and Cons of top-down integration testing Test cases can be defined in terms of the functionality of the system (functional requirements) Writing stubs can be difficult: Stubs must allow all possible conditions to be tested. Possibly a very large number of stubs may be required, especially if the lowest level of the system contains many methods. One solution to avoid too many stubs: Modified top-down testing strategy Test each layer of the system decomposition individually before merging the layers Disadvantage of modified top-down testing: Both, stubs and drivers are needed Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 11 Sandwich Testing Strategy Combines top-down strategy with bottom-up strategy The system is view as having three layers A target layer in the middle A layer above the target A layer below the target Testing converges at the target layer How do you select the target layer if there are more than 3 layers? Heuristic: Try to minimize the number of stubs and drivers Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 12

7 Sandwich Testing Strategy A Layer I B C D Layer II Test E E F G Layer III Bottom Layer Tests Test F Test G Test B, E, F Test D,G Test A, B, C, D, E, F, G Test A,B,C, D Top Layer Tests Test A Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 13 Pros and Cons of Sandwich Testing Top and Bottom Layer Tests can be done in parallel Does not test the individual subsystems thoroughly before integration Solution: Modified sandwich testing strategy Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 14

8 Modified Sandwich Testing Strategy Test in parallel: Middle layer with drivers and stubs Top layer with stubs Bottom layer with drivers Test in parallel: Top layer accessing middle layer (top layer replaces drivers) Bottom accessed by middle layer (bottom layer replaces stubs) Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 15 Modified Sandwich Testing Strategy Test B Test E Triple Triple Triple Triple Test Test B, E, F Test II Test Test II Test F E A Double Double Test Test II Layer I B C D Layer II F G Layer III Double Double Test Test II II Double Double Test Test II II Test D Test G Test D,G Test A, B, C, D, E, F, G Test A,C Test A Test C Double Double Test Test II Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 16

9 Scheduling Sandwich Tests: Example of a Dependency Chart Unit Tests Double Tests Triple Tests SystemTests Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 17 Steps in Integration-Testing Based on on the the integration strategy, select a component to to be be tested. Unit Unit test test all all the the classes in in the the component Put Put selected component together; do do any anypreliminary fix-up necessary to to make the the integration test test operational (drivers, stubs) Do Dofunctional testing: Define test test cases that that exercise all all uses uses cases with with the the selected component Do Do structural testing: Define test test cases that that exercise the the selected component Execute performance tests tests Keep Keep records of of the the test test cases and and testing activities Repeat steps steps 1 to to 7 until until the the full full system is is tested. The The primary goal goal of of integration testing is is to to identify errors in in the the (current) component configuration. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 18

10 Which Integration Strategy should you use? Factors to to consider Amount of of test test harness (stubs &drivers) Location of of critical parts in in the the system Availability of of hardware Availability of of components Scheduling concerns Bottom up up approach good good for for object oriented design methodologies Test Test driver interfaces must match component interfaces top-level components are are usually important and and cannot be be neglected up up to to the the end end of of testing Detection of of design errors postponed until until end end of of testing Top Top down approach Test Test cases can can be be defined in in terms of of functions examined Need to to maintain correctness of of test test stubs Writing stubs can can be be difficult Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 19 System Testing Functional Testing Structure Testing Performance Testing Acceptance Testing Installation Testing Impact of requirements on system testing: The more explicit the requirements, the easier they are to test. Quality of use cases determines the ease of functional testing Quality of subsystem decomposition determines the ease of structure testing Quality of nonfunctional requirements and constraints determines the ease of performance tests: Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 20

11 Structure Testing Essentially the same as white box testing. Goal: Cover all paths in the system design Exercise all input and output parameters of each component. Exercise all components and all calls (each component is called at least once and every component is called by all possible callers.) Use conditional and iteration testing as in unit testing. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 21 Functional Testing Essentially. the same as black box testing Goal: Test functionality of system Test cases are designed from the requirements analysis document (better: user manual) and centered around requirements and key functions (use cases) The system is treated as black box. Unit test cases. can be reused, but in end user oriented new test cases have to be developed as well. Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 22

12 Performance Testing Stress Testing Stress limits of system (maximum # of users, peak demands, extended operation) Volume testing Test what happens if large amounts of data are handled Configuration testing Test the various software and hardware configurations Compatibility test Test backward compatibility with existing systems Security testing Try to violate security requirements Timing testing Evaluate response times and time to perform a function Environmental test Test tolerances for heat, humidity, motion, portability Quality testing Test reliability, maintain- ability & availability of the system Recovery testing Tests system s response to presence of errors or loss of data. Human factors testing Tests user interface with user Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 23 Test Cases for Performance Testing Push the (integrated) system to its limits. Goal: Try to break the subsystem Test how the system behaves when overloaded. Can bottlenecks be identified? (First candidates for redesign in the next iteration Try unusual orders of execution Call a receive() before send() Check the system s response to large volumes of data If the system is supposed to handle 1000 items, try it with 1001 items. What is the amount of time spent in different use cases? Are typical cases executed in a timely fashion? Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 24

13 Acceptance Testing Goal: Demonstrate system is is ready for for operational use Choice of of tests tests is is made by by client/sponsor Many tests tests can can be be taken from integration testing Acceptance test test is is performed by by the the client, not not by by the the developer. Majority of of all all bugs bugs in in software is is typically found by by the the client after after the the system is is in in use, use, not not by by the the developers or or testers. Therefore two two kinds of of additional tests: tests: Alpha test: Sponsor uses uses the the software at at the the developer s site. site. Software used used in in a controlled setting, with with the the developer always ready to to fix fix bugs. Beta test: Conducted at at sponsor s site site (developer is is not not present) Software gets gets a realistic workout in in target environment Potential customer might get get discouraged Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 25 Testing has its own Life Cycle Establish the test objectives Design the test cases Write the test cases Test the test cases Execute the tests Evaluate the test results Change the system Do regression testing Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 26

14 Test Team Analyst Professional Tester Programmer too familiar with code User Test Team System Designer Configuration Management Specialist Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 27 Summary Testing is is still a black art, but many rules and heuristics are are available Testing consists of ofcomponent-testing (unit testing, integration testing) and system testing Design Patterns can be be used for for integration testing Testing has its its own lifecycle Bernd Bruegge & Allen H. Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 28