Chapter 11, Testing

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• Chapter 11, Testing

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• Tell me how are you going to test the CALCULATOR

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To Summarize the calculator example

• Valid Input
• Invalid Input
• Character A, B, C,
• Abnormal sequence
• Boundary test
• Large number
• Negative number
• zero
• Check internal implementation boundaries
• size of stack
• Non-functional test
• Performance test
• Appearance
• Usability
• Documentation
• Timing

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How to design test cases?

• Test the functional requirement
• Use case testing
• Black box testing
• Equivalence partition testing
• Boundary testing
• .
• Test the non-functional requirement
• Performance testing
• Acceptance testing
• Installation testing
• .

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Black box testing

• Also known as functional testing. A software
  testing technique whereby the internal workings
  of the item being tested are not known by the
  tester.
• For example, in a black box test on a software
  design the tester only knows the inputs and what
  the expected outcomes should be and not how the
  program arrives at those outputs.
• The tester does not ever examine the programming
  code and does not need any further knowledge of
  the program other than its specifications.

http//www.webopedia.com/TERM/B/Black_Box_Testing.
html
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Black box testing

• The advantages of this type of testing include
• The test is unbiased because the designer and the
  tester are independent of each other.
• The tester does not need knowledge of any
  specific programming languages.
• The test is done from the point of view of the
  user, not the designer.
• Test cases can be designed as soon as the
  specifications are complete.
• The disadvantages of this type of testing
  include
• The test can be redundant if the software
  designer has already run a test case.
• The test cases are difficult to design.
• Testing every possible input stream is
  unrealistic because it would take a inordinate
  amount of time therefore, many program paths
  will go untested.

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White box testing

• Also known as glass box, structural, clear box
  and open box testing. A software testing
  technique whereby explicit knowledge of the
  internal workings of the item being tested are
  used to select the test data.
• Unlike black box testing, white box testing uses
  specific knowledge of programming code to examine
  outputs. The test is accurate only if the tester
  knows what the program is supposed to do. He or
  she can then see if the program diverges from its
  intended goal.
• White box testing does not account for errors
  caused by omission, and all visible code must
  also be readable.

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Black box testing and white box testing compared

• White box testing is concerned only with testing
  the software product, it cannot guarantee that
  the complete specification has been implemented.
• Black box testing is concerned only with testing
  the specification, it cannot guarantee that all
  parts of the implementation have been tested.
• Thus black box testing is testing against the
  specification and will discover
  faults of omission, indicating that part of the
  specification has not been fulfilled.
• White box testing is testing against the
  implementation and will discover
  faults of commission, indicating that part of the
  implementation is faulty.
• In order to fully test a software product both
  black and white box testing are required.

http//www.scism.sbu.ac.uk/law/Section5/chap3/s5c3
p23.html
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Black box testing and white box testing compared

• White box testing is much more expensive than
  black box testing. It requires the source code to
  be produced before the tests can be planned and
  is much more laborious in the determination of
  suitable input data and the determination if the
  software is or is not correct.
• The advice given is to start test planning with a
  black box test approach as soon as the
  specification is available.
• White box planning should commence as soon as all
  black box tests have been successfully passed,
  with the production of flowgraphs and
  determination of paths. The paths should then be
  checked against the black box test plan and any
  additional required test runs determined and
  applied.

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Quality assurance vs. quality control

• The consequences of test failure at this stage
  may be very expensive.
• A failure of a white box test may result in a
  change which requires all black box testing to be
  repeated and the re-determination of the white
  box paths.
• The cheaper option is to regard the process of
  testing as one of quality assurance rather than
  quality control. The intention is that sufficient
  quality will be put into all previous design and
  production stages so that it can be expected that
  testing will confirm that there are very few
  faults present, quality assurance, rather than
  testing being relied upon to discover any faults
  in the software, quality control.

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Test Cases

• A test case is a set of input data and expected
  results that exercises a component with the
  purpose of causing failures and detecting faults.
• A test case has five attributes.

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Testing from the development process point of
view
Requirement
Final System
Implementation Testing
Design
Test case development Testing
Requirement
Final System
Design Implementation
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Review of last class
Case Study Example the calculator
Testing Computer Software, Cem Kaner, Jack Falk,
Hung Quoc Nguyen
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The objectives and limits of Testing

• You cant test a program completely
• You cant test the programs response to every
  possible Input
• Youd have to test all valid inputs
• Youd have to test all invalid inputs, e.g.,
  everything that you can enter at the keyboard
• Youd have to test all edited inputs the
  ltBackspacegt example
• Youd have to test all variations on input timing
• You cant test every path the program can take
• Myers simple program in 1979 20 lines of code,
  100 trillion paths a faster tester could test
  them in a billion years.
• Specifications often contain errors.
• You cant prove programs correct using logic
  how do you prove the proof procedure is correct.

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The objectives and limits of Testing

• The program doesnt work correctly
• Beizers review estimates the average number of
  errors in programs released to Testing at 1 to 3
  bugs per 100 executable statements -- These are
  public bugs
• Private bugs before releasing to the tester
  1.5 errors per executable statement. Most
  programmers catch and fix more than 99 of their
  mistakes before releasing a program for testing.
• Is testing a failure if the program doesnt work
  correctly
• We have seen project managers blame testers for
  continuing to find errors in a program thats
  behind schedule.
• Testers shouldnt want to verify that a program
  runs correctly
• If you think your task is to find problems, you
  will look harder for them than if you think your
  task is to verify that the program has none
  (Myers, 1979)

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So, Why Test?
The purpose of testing a program is to find
problems in it
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Outline

• Terminology
• Types of errors
• Dealing with errors
• Component Testing
• Unit testing
• Integration testing
• Testing Strategy

• System testing
• Function testing
• Structure Testing
• Performance testing
• Acceptance testing
• Installation testing

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What is this?
A failure?
An error?
A fault?
Need to specifythe desired behavior first!
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Terminology

• Failure Any deviation of the observed behavior
  from the specified behavior.
• Error 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.
• Reliability The measure of success with which
  the observed behavior of a system confirms to
  some specification of its behavior.
• Software reliability is the probability that a
  software system will not cause system failure for
  a specified time under specified conditions.
• There are many different types of errors and
  different ways how we can deal with them.

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How do we deal with Errors and Faults?
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Verification?
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Modular Redundancy?
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Declaring the Bug as a Feature?
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Patching?
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Testing?
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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

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Dealing with Errors

• Verification
• The assumptions made in verification might be
  wrong
• Proof might be buggy (omits important
  constraints simply wrong)
• Nevertheless, sometimes verification is required
• How do you test a surgery robot
• Modular redundancy
• Expensive
• Declaring a bug to be a feature
• Bad practice
• Patching
• Slows down performance
• Testing (this lecture)
• Testing is never good enough

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Another View on How to Deal with Errors

• Error prevention (before the system is released)
• Use good programming methodology to reduce
  complexity
• Use version control to prevent inconsistent
  system
• Apply verification to prevent algorithmic bugs
• Error detection (while system is running)
• Testing Create failures in a planned way
• Debugging Start with an unplanned failures
• Monitoring Deliver information about state. Find
  performance bugs
• Error recovery (recover from failure once the
  system is released)
• Data base systems (atomic transactions)
• Modular redundancy
• Recovery blocks

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Some Observations

• It is impossible to completely test any
  nontrivial module or any system
• Theoretical limitations Halting problem
• Practial limitations Prohibitive in time and
  cost
• Testing can only show the presence of bugs, not
  their absence (Dijkstra)

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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
• "Dont mess up my code!"
• A program often does not work when tried by
  somebody else.
• Don't let this be the end-user.

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Quiz 2
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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)

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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

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Are These Enough?

• Two Interesting Test Cases
• Create a folder named as CON (doesnt matter if
  capital letter or small letter)
• Open Microsoft Word and type rand(200,99)

• What is the best way to test these kinds of
  faults?
• Another solution to select only a limited amount
  of test cases
• Get knowledge about the inner workings of the
  unit being tested gt white-box testing

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Boundary Testing

• A special case of equivalence testing
• Focuses on the condition at the boundary of the
  equivalence classes.
• The assumption behind boundary testing is that
  developers often overlook special cases at the
  boundary of the equivalence classes (e.g., 0,
  empty strings, year 2000).

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White-box Testing

• Focus Thoroughness (Coverage). Every statement
  in the component is executed at least once.
• Types of white-box testing
• Path Testing
• Loop Testing
• State-Based testing

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White-box Testing (Continued)

• Path testing
• Make sure all paths in the program are executed
• 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

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Path testing

• The assumption behind path testing is that, by
  exercising all possible paths through the code at
  least once, most faults will trigger failures.
• The starting point for path testing is the flow
  graph.

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Calculating the minimal number of test cases
Number of independent paths through the flow
graph. This is defined as the cyclomatic
complexity CC CC number of edges number of
nodes 2 A path is linearly independent from
others means the path can not be expressed by
linear combinations of others.
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Path testing (continue)

• An example on book P. 456, 457,458
• Using graph theory, it can be shown that the
  number of independent paths through the flow
  graph.
• CC number of edges number of nodes 2

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For the example on book
Number of Test cases 18 14 2 6
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Loop Testing

• A white box testing technique that exercises
  program loops
• Loops are a highly fault-prone portion of source
  code.
• Concatenated loops
• Nested loops
• Horrible loops

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Loop Testing Example
FindMean(float Mean, FILE ScoreFile)
SumOfScores 0.0 NumberOfScores 0 Mean 0
/Read in and sum the scores/
Read(Scor
eFile, Score)
while (! EOF(ScoreFile)
if ( Score gt 0.0 )

SumOfScores SumOfScores Score

NumberOfScores


Read(ScoreFile, Score)

/ Compute the mean and print the result /
if (NumberOfScores gt 0 )

Mean SumOfScores/NumberOfScores
printf("The mean score is f \n", Mean)
else
printf("No scores found in file\n")

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White-box Testing Example Determining the Paths
FindMean (FILE ScoreFile) float SumOfScores
0.0 int NumberOfScores 0 float Mean0.0
float Score Read(ScoreFile, Score) while (!
EOF(ScoreFile) if (Score gt 0.0 ) SumOfScores
SumOfScores Score NumberOfScores Read(S
coreFile, Score) / Compute the mean and print
the result / if (NumberOfScores gt 0) Mean
SumOfScores / NumberOfScores printf( The mean
score is f\n, Mean) else printf (No scores
found in file\n)
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Constructing the Logic Flow Diagram
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Finding the Test Cases
Start
1
a (Covered by any data)
2
b
(Data set must contain at least
one value)
3
(Positive score)
d
e
(Negative score)
c
5
4
(Data set must
h
(Reached if either f or
g
f
be empty)
6
e is reached)
7
j
i
(Total score gt 0.0)
(Total score lt 0.0)
9
8
k
l
Exit
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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

Loop testing and path testing can work
together For the previous example path testing
13-112 4
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Calculating the minimal number of test cases
Number of independent paths through the flow
graph. This is defined as the cyclomatic
complexity CC CC number of edges number of
nodes 2 A path is linearly independent from
others means the path can not be expressed by
linear combinations of others.
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Constructing the Logic Flow Diagram
0
Test cases 11-102 3 P1 0, 1, 2, 3, 4, 6, 7,
8, 10 P2 0, 1, 2, 3, 5, 6, 7, 8, 10 P3 0, 1, 2,
3, 4, 6, 7, 9, 10 P4 0, 1, 2, 3, 5, 6, 7, 9,
10 P4 P3 P2 P1
10
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Constructing the Logic Flow Diagram
Test cases 13-112 4 P1 0, 1, 2, 3, 4, 6, 2,
7, 8, 10 P2 0, 1, 2, 3, 5, 6, 2, 7, 8, 10 P3 0,
1, 2, 7, 8, 10 P4 0, 1, 2, 7, 9, 10 P5 0, 1,
2, 3, 5, 6, 2, 7, 9, 10 P4 P2 P4 P3
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Test Cases
start
i0 xy

• testMethod( int y, int v)
• int i0
• int x y
• for (i0 ilt v i)
• if (xgt0)
• do A
• else
• do B
• System.out.println(finish method)

for loop
5
xgt0?
A
B
print
end
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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

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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

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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

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Testing Activities
Requirements Analysis Document
Subsystem Code
Requirements Analysis Document
Unit
System Design Document
T
est
Tested Subsystem
User Manual
Subsystem Code
Unit
T
est
Integration
Tested Subsystem
Functional
Test
Test
Functioning System
Integrated Subsystems
Tested Subsystem
Subsystem Code
Unit
T
est
All tests by developer
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Testing Activities continued
Clients Understanding of Requirements
User Environment
Global Requirements
Accepted System
Validated System
Functioning System
Performance
Acceptance
Installation
Test
Test
Test
Usable System
Tests by client
Tests by developer
Users understanding
System in
Use
Tests (?) by user
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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

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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

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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)

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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
• Dont 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

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Test Stubs and Drivers

• A test driver simulates the part of the system
  that calls the component under test.
• A test stub simulates components that are called
  by the tested component and must return a value
  compliant with the return result type of the
  methods type signature

Program to be tested
Driver
Stub
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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

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Example Three Layer Call Hierarchy
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Integration Testing Big-Bang Approach
Unit Test A
Dont try this!
Unit Test B
Unit Test C
Unit Test D
Unit Test E
Unit Test F
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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

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Bottom-up Integration
Test E
Test F
Test C
Test G
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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

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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.

70
Top-down Integration Testing
Test A
Layer I
71
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

72
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

73
Sandwich Testing Strategy
Test E
Test A, B, C, D, E, F, G
Test A,B,C, D
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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

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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)

76
Modified Sandwich Testing Strategy
77
Scheduling Sandwich Tests Example of a
Dependency Chart
SystemTests
Triple Tests
Unit Tests
Double Tests
78
Steps in Integration-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

• 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.

.
79
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
• ...

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

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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

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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.

82
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.

.
83
Performance Testing

• 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 systems response to presence of errors or
  loss of data.
• Human factors testing
• Tests user interface with user

• 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

84
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 systems 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?

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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 developers
  site.
• Software used in a controlled setting, with the
  developer always ready to fix bugs.
• Beta test
• Conducted at sponsors site (developer is not
  present)
• Software gets a realistic workout in target
  environ- ment
• Potential customer might get discouraged

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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
87
Test Team
Professional Tester
too familiar
Programmer
with code
Analyst
System Designer
Test
User
Team
Configuration Management Specialist
88
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 integration
  testing
• Testing has its own lifecycle