Lecture 1 for Chapter 9, Testing

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Transcript Lecture 1 for Chapter 9, Testing

Chapter 11: Testing

Outline

       Terminology Types of errors Dealing with errors Quality assurance vs Testing Component Testing 

Unit testing



Integration testing

Testing Strategy Design Patterns & Testing  System testing 

Function testing



Structure Testing



Performance testing



Acceptance testing



Installation testing Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 2

Terminology

   

Reliability:

behavior of a system confirms to some specification of its behavior.

The measure of success with which the observed

Failure:

Any deviation of the observed behavior from the specified behavior.

Erroneous State:

The system is in a state such that further processing by the system will lead to a failure.

Fault (Bug):

The mechanical or algorithmic cause of an error.

There are many different types of errors and different ways how we can deal with them.

3 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Examples of Faults and Errors

  Faults in the Interface specification 

Mismatch between what the client needs and what the server offers



Mismatch between requirements and implementation

Algorithmic Faults 

Missing initialization



Branching errors (too soon, too late)



Missing test for nil

  Mechanical Faults (very hard to find) 

Documentation does not match actual conditions or operating procedures

Errors 

Stress or overload errors



Capacity or boundary errors



Timing errors



Throughput or performance errors 4 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Dealing with Faults

  

Fault avoidance

(without execution): 

Use good programming methodology



Use version control to prevent inconsistent system



Perform inspections and verification to catch algorithmic bugs

Fault detection

(through system execution): 

Testing: Create failures in a planned way



Debugging: Start with an unplanned failures



Monitoring: Deliver information about state. Find performance bugs

Fault tolerance

(recover from failure once the system is released): 

Data base systems (atomic transactions)



Modular redundancy



Recovery blocks 5 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Testing

   Testing is NOT the process of demonstrating that faults are not present.

Testing is the systematic method of detecting faults by creating failures and erroneous states in a planned way.



It is impossible to completely test any nontrivial module or any system



Testing can only show the presence of bugs, not their absence (Dijkstra)

Other validation methods: 

Inspections and reviews detect faults by using a structured approach to reading the code and design artifacts.



Formal verification detects faults through mathematical proofs of correctness.

6 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Testing takes creativity

     Testing often viewed as dirty work.

To develop an effective test, one must have:   

Detailed understanding of the system Knowledge of the testing techniques Skill to apply these techniques in an effective and efficient manner

Testing is done best by independent testers 

We often develop a certain mental attitude that the program should in a certain way when in fact it does not.

Programmer often stick to the data set that makes the program work 

"Don’t mess up my code!"

A program often does not work when tried by somebody else.



Don't let this be the end-user.

Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 7

Testing Activities

Subsystem Code Subsystem Code Subsystem Code Unit Test

Tested Subsystem

Unit Test

Tested Subsystem

System Design Document Requirements Analysis Document Integration Test

Integrated Subsystems

Functional Test

Tested Subsystem

Unit Test All tests by developer User Manual

Functioning System

8 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Testing Activities continued

Global Requirements Client’s Understanding of Requirements User Environment

Functioning System

Performance Test

Validated System

Acceptance Test

Accepted System

Installation Test

Tests by developer Modified from Bruegge & Dutoit’s originals Tests by client

Usable System

User’s understanding Tests (?) by user Object-Oriented Software Engineering: Using UML, Patterns, and Java

System in Use

Fault Handling Techniques

Fault Handling Fault Avoidance Fault Detection Design Methodology Reviews Verification Configuration Management Testing Fault Tolerance Atomic Transactions Debugging Modular Redundancy Unit Testing Integration Testing System Testing Correctness Debugging Performance Debugging Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 10

Quality Assurance encompasses Testing

Quality Assurance Scenario Testing Usability Testing Prototype Testing Product Testing Fault Avoidance Verification Configuration Management Fault Detection Fault Tolerance Atomic Transactions Modular Redundancy Reviews Walkthrough Inspection Unit Testing Modified from Bruegge & Dutoit’s originals Debugging Testing Integration Testing System Testing Correctness Debugging Object-Oriented Software Engineering: Using UML, Patterns, and Java Performance Debugging 11

Design and Code Review or Inspection

     A formalized procedure for reading design and code artifacts with the purpose of detecting faults.

Involves a team of developers in the role of reviewers.

Traditional steps:    

Preparation – reviewers become familiar with the design or code and record any issues found in the process Meeting – a reader paraphrases the design or code and the reviewers raise issues as the reader proceeds at a measured reading rate; a moderator controls the pace of the meeting and keeps discussions focused Rework – the author resolves the issues and repairs the faults Follow-up – the moderator checks the rework and determines the disposition of the inspection (accept, accept with fixes, re-review)

Inspections are usually done at the unit or component level Inspections complement unit testing as they tend to find different types of faults

12 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Types of Testing

  Unit Testing:  

Individual subsystem Carried out by developers



Goal: Confirm that subsystems is correctly coded and carries out the intended functionality

Integration Testing:   

Groups of subsystems (collection of classes) and eventually the entire system Carried out by developers Goal: Test the interface among the subsystem Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 13

System Testing

  System Testing: 

The entire system



Carried out by developers



Goal: Determine if the system meets the requirements (functional and global)

Acceptance Testing: 

Evaluates the system delivered by developers



Carried out by the client. May involve executing typical transactions on site on a trial basis



Goal: Demonstrate that the system meets customer requirements and is ready to use

 Implementation (Coding) and testing go hand in hand

Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 14

Unit Testing

   Informal: 

Incremental coding

Static Analysis:    

Hand execution: Reading the source code Walk-Through (informal presentation to others) Code Inspection (formal presentation to others) Automated Tools checking for



syntactic and semantic errors



departure from coding standards

Dynamic Analysis:   

Black-box testing (Test the input/output behavior) White-box testing (Test the internal logic of the subsystem or object) Data-structure based testing (Data types determine test cases) 15 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Black-box Testing

  Focus: I/O behavior. If for any given input, we can predict the output, then the module passes the test.



Almost always impossible to generate all possible inputs ("test cases")

Goal: Reduce number of test cases by equivalence partitioning: 

Divide input conditions into equivalence classes



Choose test cases for each equivalence class. (Example: If an object is supposed to accept a negative number, testing one negative number is enough) Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 16

Black-box Testing (Continued)

  Selection of equivalence classes (No rules, only guidelines): 

Input is valid across range of values. Select test cases from 3 equivalence classes:

  

Below the range Within the range Above the range



Input is valid if it is from a discrete set. Select test cases from 2 equivalence classes:

 

Valid discrete value Invalid discrete value

Another solution to select only a limited amount of test cases: 

Get knowledge about the inner workings of the unit being tested => white-box testing 17 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

White-box Testing

  Focus: Thoroughness (Coverage). Every statement in the component is executed at least once.

Types of white-box testing 

Statement Testing



Loop Testing



Path Testing



Branch Testing



State-based Testing Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 18

White-box Testing (Continued)

    Statement Testing (Algebraic Testing): Test single statements (Choice of operators in polynomials, etc) Loop Testing:   

Cause execution of the loop to be skipped completely. (Exception: Repeat loops) Loop to be executed exactly once Loop to be executed more than once

Path testing: 

Make sure all paths in the program are executed

Branch Testing (Conditional Testing): Make sure that each possible outcome from a condition is tested at least once

if ( i = TRUE) printf("YES\n"); Test cases: 1) i = TRUE; 2) i = FALSE Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 19

White-box Testing Example

FindMean(float Mean, FILE ScoreFile) { SumOfScores = 0.0; NumberOfScores = 0; Mean = 0; Read(ScoreFile, Score); /*Read in and sum the scores*/ while (! EOF(ScoreFile) { if ( Score > 0.0 ) { } SumOfScores = SumOfScores + Score; NumberOfScores++; } Read(ScoreFile, Score); } /* Compute the mean and print the result */ if (NumberOfScores > 0 ) { Mean = SumOfScores/NumberOfScores; printf("The mean score is %f \n", Mean); } else printf("No scores found in file\n"); Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 20

White-box Testing Example: Determining the Paths

FindMean (FILE ScoreFile)

{

2 float SumOfScores = 0.0; int NumberOfScores = 0; float Mean=0.0; float Score;

Read(ScoreFile, Score); while (! EOF(ScoreFile) {

if (Score > 0.0 ) {

5 1

SumOfScores = SumOfScores + Score; NumberOfScores++; } }

7 4

Read(ScoreFile, Score);

} /* Compute the mean and print the result */ if (NumberOfScores > 0) { Mean = SumOfScores / NumberOfScores; printf(“ The mean score is %f\n”, Mean); } else printf (“No scores found in file\n”);

9 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 21 8

Constructing the Logic Flow Diagram

Start 1 4 F 2 T T 3 F 6 5 T 7 F 8 9 Exit

Object-Oriented Software Engineering: Using UML, Patterns, and Java Modified from Bruegge & Dutoit’s originals 22

Finding the Test Cases

(Positive score) c (Data set must be empty) 4 f d Start 1 a (Covered by any data) 2 b (Data set must contain at least one value) 3 6 e (Negative score) 5 g h (Reached if either f or e is reached) (Total score < 0.0) 8 i k 7 Exit l j (Total score > 0.0) 9

23 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Test Cases

   Test case 1 : ? (To execute loop exactly once) Test case 2 : ? (To skip loop body) Test case 3: ?,? (to execute loop more than once) These 3 test cases cover all control flow paths

Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 24

Dealing with Polymorphism

  Polymorphism enables invocations to be bound to different methods based on the class of the target 

Leads to compact code and increased reuse



Introduces many new cases to test

Strategy 

Consider all possible dynamic bindings and convert the invocation into an if-then-else statement for each potential dynamic binding



Perform path testing Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 25

State-Based Testing

    Instead of comparing actual and expected outputs, state-based testing compares resulting state with expected state Each test case consists of starting state, stimuli, expected next state Useful for classes with complex state transition diagrams Steps 

Derive test cases from the statechart model



For each state, derive equivalence classes of stimuli to activate each transition



Instrument each attribute of the class in order to compute the new state of the class 26 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Example Statechart Diagram

pressButtonL pressButtonR 3.pressButtonsLAndR

MeasureTime SetTime 6.

pressButtonL pressButtonR 4.after 2 min.

5.pressButtonsLAndR/beep 7.after 20 years 8.after 20 years DeadBattery

Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 27

Comparison of White & Black-box Testing

  White-box Testing:   

Potentially infinite number of paths have to be tested White-box testing often tests what is done, instead of what should be done Cannot detect missing use cases

Black-box Testing:   

Potential combinatorical explosion of test cases (valid & invalid data) Often not clear whether the selected test cases uncover a particular error Does not discover extraneous use cases ("features")

   Both types of testing are needed White-box testing and black box testing are the extreme ends of a testing continuum. Any choice of test case lies in between and depends on the following:    

Number of possible logical paths Nature of input data Amount of computation Complexity of algorithms and data structures 28 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

The 4 Testing Steps

1. Select what has to be measured 

Analysis: Completeness of requirements



Design: tested for cohesion



Implementation: Code tests

2. Decide how the testing is done 

Code inspection



Proofs (Design by Contract)



Black-box, white box,



Select integration testing strategy (big bang, bottom up, top down, sandwich)

3. Develop test cases 

A test case is a set of test data or situations that will be used to exercise the unit (code, module, system) being tested or about the attribute being measured

4. Create the test oracle 

An oracle contains of the predicted results for a set of test cases



The test oracle has to be written down before the actual testing takes place Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 29

Guidance for Test Case Selection

  Use

analysis knowledge

about functional requirements (black-box testing): 

Use cases

 

Expected input data Invalid input data

Use

design knowledge

about system structure, algorithms, data structures (white-box testing): 

Control structures



Test branches, loops, ...



Data structures



Test records fields, arrays, ...

 Use

implementation knowledge

about algorithms: 

Examples:



Force division by zero



Use sequence of test cases for interrupt handler Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 30

Unit-testing Heuristics

1. Create unit tests as soon as object design is completed: 

Black-box test: Test the use cases & functional model



White-box test: Test the dynamic model



Data-structure test: Test the object model

2. Develop the test cases 

Goal: Find the minimal number of test cases to cover as many paths as possible

3. Cross-check the test cases to eliminate duplicates 

Don't waste your time!

4. Desk check your source code 

Reduces testing time

5. Create a test harness 

Test drivers and test stubs are needed for integration testing

6. Describe the test oracle 

Often the result of the first successfully executed test

7. Execute the test cases  

Don’t forget regression testing Re-execute test cases every time a change is made.

8. Compare the results of the test with the test oracle 

Automate as much as possible Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 31

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

32 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

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 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 33

Example: Three Layer Call Hierarchy

A B C D Layer I Layer II E F G Layer III Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 34

Integration Testing: Big-Bang Approach

Unit Test A Unit Test B Unit Test C Unit Test D Unit Test E Unit Test F Don’t try this!

System Test 35 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

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 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 36

Bottom-up Integration

Test E Test F Test B, E, F Test C E B F A C D G Layer I Layer II Layer III Test A, B, C, D, E, F, G Test D,G Test G Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 37

Pros and Cons of bottom up integration testing

  Tests some important subsystems (user interface) last Useful for integrating the following systems 

Object-oriented systems



real-time systems



systems with strict performance requirements Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 38

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.

SeatDriver (simulates VIP) Seat Interface (in Vehicle Subsystem) Seat Implementation Modified from Bruegge & Dutoit’s originals Stub Code Simulated Seat (SA/RT) Object-Oriented Software Engineering: Using UML, Patterns, and Java Real Seat 39

Top-down Integration Testing

E B F A C D G Layer I Layer II Layer III Test A Layer I Test A, B, C, D Test A, B, C, D, E, F, G Layer I + II All Layers Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 40

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

Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 41

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



Write drivers and stubs for target layer



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

Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 42

Sandwich Testing Strategy

E B F A C Test E Bottom Layer Tests Test F Test B, E, F Test D,G Test G Test A,B,C, D Top Layer Tests Test A Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java D G Layer I Layer II Layer III Test A, B, C, D, E, F, G 43

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

Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 44

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)

Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 45

Modified Sandwich Testing Strategy

Triple Test I Test E Test F Test B Test B, E, F Triple Test I E B F A C Double Test I Layer I D Layer II G Layer III Double Test II Double Test II Test D Test D,G Test A, B, C, D, E, F, G Test G Test A,C Test A Test C Double Test I Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 46

Scheduling Sandwich Tests: Example of a Dependency Chart

Unit Tests Modified from Bruegge & Dutoit’s originals Double Tests Triple Tests Object-Oriented Software Engineering: Using UML, Patterns, and Java SystemTests 47

Steps in Integration-Testing

1. Based on the integration strategy,

select a component

component.

to be tested. Unit test all the classes in the .

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 4. Do

structural testing:

component Define test cases that exercise the selected 5. Execute

performance tests

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.

48 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Which Integration Strategy should you use?

  Factors to consider 

Amount of test harness (stubs &drivers)



Location of critical parts in the system



Availability of hardware



Availability of components



Scheduling concerns

Bottom up approach 

good for object oriented design methodologies



Test driver interfaces must match component interfaces



...

 

...Top-level components are usually important and cannot be neglected up to the end of testing



Detection of design errors postponed until end of testing

Top down approach 

Test cases can be defined in terms of functions examined



Need to maintain correctness of test stubs



Writing stubs can be difficult 49 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

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: 50 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

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.

Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 51

Functional 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 user-oriented test cases have to be developed as well.

Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 52

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 53 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

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?

54 Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java

Acceptance Testing

  Goal: Demonstrate system is ready for operational use 

Choice of tests is made by client/sponsor



Many tests can be taken from integration testing



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 two kinds of additional tests:  

Alpha test:



Sponsor uses the software at the

developer’s site.



Software used in a controlled setting, with the developer always ready to fix bugs.

Beta test:



Conducted at

sponsor’s site

(developer is not present)



Software gets a realistic workout in target environ ment



Potential customer might get discouraged Modified from Bruegge & Dutoit’s originals Object-Oriented Software Engineering: Using UML, Patterns, and Java 55

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

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Test Team

Analyst Professional Tester

Programmer

too familiar with code

User

Test Team

System Designer

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Configuration Management Specialist

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Test Plan

          Introduction Relationship to other documents System overview (overview of components, esp. for unit test) Test coverage (features to be tested/not to be tested) Pass/Fail criteria Approach Suspension and resumption Testing materials (hardware/software requirements) Test cases Testing schedule

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Test Case Specification

       Test case specification identifier Test items Input specifications Output specifications Environmental needs Special procedural requirements Intercase dependencies

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Test Automation

      Regression testing – verify that changes to the system do not lead to new failures and erroneous states.

re-running system and integration tests to In practice, many tests need to be repeatedly run as part of regression testing.

Test automation can save a significant amount of testing effort and staff needs.

Test cases – specified in terms of sequence of inputs and their expected outputs Test harness – automatically executes the test cases and compares actual output with expected output This requires an investment to develop.

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Automated Test Infrastructure Example: JUnit

TestResult Test run(TestResult) TestCase testName:String run(TestResult) setUp() tearDown() runTest() TestSuite run(TestResult) addTest() ConcreteTestCase setUp() tearDown() runTest()

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Using JUnit

     Write new test case by subclassing from TestCase Implement setUp() and tearDown() methods to initialize and clean up Implement runTest() method to run the test harness and compare actual with expected values Test results are recorded in TestResult A collection of tests can be stored in TestSuite.

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Summary

    Testing is still a black art, but many rules and heuristics are available Testing consists of component-testing testing) and system testing ( unit testing, integration Design Patterns can be used for integration testing Testing has its own lifecycle

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