Using UML Patterns and Java ObjectOriented Software Engineering
Using UML, Patterns, and Java Object-Oriented Software Engineering Chapter 11, Testing Integration, System, and Acceptance Testing
Component-Based Testing Strategy ¨ ¨ The entire system is viewed as a collection of subsystems (sets of classes) determined during the system and object design. Once faults in each component have been removed and the test cases do not reveal any new fault components they are ready to be integrated in a larger subsystems or system. The order in which the subsystems are selected for testing and integration determines the testing strategy w Big bang integration (Non-incremental) w Bottom up integration w Top down integration w Sandwich testing w Variations of the above For the selection use the system decomposition from the System Design Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 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) Stub Code Bernd Bruegge & Allen Dutoit Seat Implementation Simulated Seat (SA/RT) Object-Oriented Software Engineering: Using UML, Patterns, and Java Real Seat 3
Example of a hierarchal system decomposition with three layers (UML class diagram, layers represented by packages). Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 4
Example: Three Layer Call Hierarchy A C B E Bernd Bruegge & Allen Dutoit Layer I F D Layer II G Layer III Object-Oriented Software Engineering: Using UML, Patterns, and Java 5
Integration Testing: Big-Bang Approach Unit Test UI (A) Don’t try this! Unit Test Billing (B) Unit Test Learning (D) Unit Test Event Service (C) System Test PAID Unit Test Network (F) Unit Test Database (E) Unit Test Database (G) Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 6
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: w A routine that calls a particular subsystem and passes a test case to it ¨ Note that no test stub are necessary. Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 7
Bottom-up Integration A Triple Test C B Test E E Layer I F D G Layer III Test B, E, F Test C Test A, B, C, D, E, F, G Test D, G Test G Double Test Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 8
Pros and Cons of bottom up integration testing ¨ ¨ Bad for functionally decomposed systems: w Tests the most important subsystem last Useful for integrating the following systems w Object-oriented systems w real-time systems with strict performance requirements Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 9
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 : w 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 Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 10
Top-down Integration Testing A C B E Test A, B, C, D Layer I D G F Layer III Test A, B, C, D, E, F, G Layer I + II All Layers Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 11
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. Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 12
Sandwich Testing Strategy ¨ ¨ ¨ Combines top-down strategy with bottom-up strategy The system is view as having three layers w A target layer in the middle w A layer above the target w A layer below the target w Testing converges at the target layer How do you select the target layer if there are more than 3 layers? w Heuristic: Try to minimize the number of stubs and drivers Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 13
Sandwich Testing Strategy A Target layer Bottom Layer Tests C B E Test E Layer I F D G Layer III Test B, E, F Test D, G Test A, B, C, D, E, F, G Test G Top Layer Tests Bernd Bruegge & Allen Dutoit Test A Object-Oriented Software Engineering: Using UML, Patterns, and Java 14
Pros and Cons of Sandwich Testing ¨ ¨ ¨ Top and Bottom Layer Tests can be done in parallel Does not test the individual subsystems of the target layer thoroughly before integration Solution: Modified sandwich testing strategy Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 15
Modified Sandwich Testing Strategy ¨ ¨ Test in parallel: w Middle layer (or target layer) with drivers and stubs w Top layer with stubs w Bottom layer with drivers The combined layer tests consist of two tests: w Top layer accesses target layer. This test can reuse the target layer tests from the individual layer tests, replacing the drivers with components from the top layer. w Bottom is accessed by the target layer. This test can reuse the target tests from the individual layer tests, replacing the stud with component from the bottom layer. Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 16
An example of modified sandwich testing strategy layers A C B E Bernd Bruegge & Allen Dutoit F Object-Oriented Software Engineering: Using UML, Patterns, and Java Layer I D Layer II G Layer III 17
Scheduling the sandwich tests in the Test Plan Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 18
Steps in Component-Based Testing 1. Based on the integration strategy, select a component to be tested. Unit test all the classes in the component. 2. . Put selected component together; do any preliminary fix-up necessary to make the integration test operational (drivers, stubs) 3. Do functional testing: Define test cases that exercise all uses cases with the selected component Bernd Bruegge & Allen Dutoit 4. Do structural testing: Define test cases that exercise the selected component 5. Execute performance tests 6. Keep records of the test cases and testing activities. 7. Repeat steps 1 to 7 until the full system is tested. The primary goal of integration testing is to identify errors in the (current) component configuration. Object-Oriented Software Engineering: Using UML, Patterns, and Java 19
Which Integration Strategy should you use? ¨ Factors to consider w Amount of test harness (stubs &drivers) w Location of critical parts in the system w Availability of hardware w Availability of components w Scheduling concerns ¨ Bottom up approach w good for object oriented design methodologies w Test driver interfaces must match component interfaces w. . . Bernd Bruegge & Allen Dutoit w. . . Top-level components are usually important and cannot be neglected up to the end of testing w Detection of design errors postponed until end of testing ¨ Top down approach w Test cases can be defined in terms of functions examined w Need to maintain correctness of test stubs w Writing stubs can be difficult Object-Oriented Software Engineering: Using UML, Patterns, and Java 20
System Testing ¨ ¨ ¨ Functional Testing Structure Testing Performance Testing Acceptance Testing Installation Testing Impact of requirements on system testing: w The more explicit the requirements, the easier they are to test. w Quality of use cases determines the ease of functional testing w Quality of subsystem decomposition determines the ease of structure testing w Quality of nonfunctional requirements and constraints determines the ease of performance tests Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 21
Functional Testing or requirements 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) w Instantiate use cases to derive test cases (use cases instances are scenarios …). scenarios (use case instances) can be achieved by applying w Different black box techniques (e. g. , equivalence class and boundary value analysis) to the input data ¨ ¨ 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 Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 22
Structure Testing ¨ Essentially ¨ the same as white box testing. Goal: Cover all paths in the system design w Exercise all input and output parameters of each component. w Exercise all components and all calls (each component is called at least once and every component is called by all possible callers. ) w Use conditional and iteration testing as in unit testing. Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 23
Performance Testing ¨ ¨ Stress Testing w Stress limits of system (maximum # of users, peak demands, extended operation) ¨ ¨ Environmental test w Test tolerances for heat, humidity, motion, portability ¨ Quality testing w Test reliability, maintainability & availability of the system ¨ Compatibility test w Test backward compatibility with existing systems ¨ ¨ Configuration testing w Test the various software and hardware configurations ¨ w Evaluate response times and time to perform a function Volume testing w Test what happens if large amounts of data are handled Timing testing Security testing Recovery testing w Tests system’s response to presence of errors or loss of data. ¨ Human factors testing w Tests user interface with user w Try to violate security requirements Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 24
Test Cases for Performance Testing ¨ ¨ Can be derived from the SDD and RAD. Push the (integrated) system to its limits. Goal: Try to break the subsystem Test how the system behaves when overloaded. w Can bottlenecks be identified? (First candidates for redesign in the next iteration ¨ Try unusual orders of execution w Call a receive() before send() ¨ Check the system’s response to large volumes of data w 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? w Are typical cases executed in a timely fashion? Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 25
Acceptance Testing ¨ Goal: ¨ Demonstrate system is ready for operational use w Choice of tests is made by client/sponsor w Many tests can be taken from integration testing w Acceptance test is performed by the client, not by the developer. Majority of all bugs in software is typically found by the client after the system is in use, not by the developers or testers. Therefore we can use a pilot test: w Alpha test w Beta test Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 26
Pilot testing ¨ ¨ ¨ The system is installed and used by a selected set of users The users freely use the system This kind of testing is often used when a system is developed without a specific set of requirements w The pilot test is carried out for a limited time ¨ ¨ Feedbacks should be provided by the users An alpha test is a pilot test with users exercising the system in the development environment w Controlled w Developer are always ready to fix bugs ¨ In the beta test end users perform the acceptance test in the target environment. w To distribute a software Internet is a good tool Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 27
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 Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 28
Test Team Professional Tester Programmer too familiar with code Analyst User Test Team System Designer Configuration Management Specialist Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 29
Summary ¨ Testing is still a black art, but many rules and heuristics are available ¨ Testing consists of component-testing (unit testing, integration testing) and system testing Design Patterns can be used for component-based testing Testing has its own lifecycle ¨ ¨ Bernd Bruegge & Allen Dutoit Object-Oriented Software Engineering: Using UML, Patterns, and Java 30
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