1. Software Testing Techniques (STT)
Unit 3 – Transaction Flow & Data Flow testing
Sudhakar yadav
Compiled with reference from:
Software Testing Techniques: Boris Beizer
Craft of Software Testing: Brain Marrick

2. Transaction-Flow TestingU2
We will see in this part of Unit 2:
Concepts of Transaction flows
Transaction-flow testing
ref boris beizer

3. Transaction-Flow TestingU2
Contents
Definitions of Transaction, Transaction flow, Transaction flow graph
It’s representation, implementation architecture in an O.S. & implementation in a system
A perspective of TFG model. View wrt DFG, CFG
Handling cases – decisions, biosis, mitosis, transactional junction, absorption & conjugation
TFG is not structured - Reasons
Transaction Flow Testing Techniques
Building transaction flows
Inspections, Reviews, and walkthroughs
Path selection
Path sensitization
Instrumentation
Test data bases
Test Execution
Transaction-flow implementation & testing related comments
Translation based systems
Hidden languages
ref boris beizer

4. Definitions of Transaction,Transaction-flow, TFGU2
Transaction-flow
Transaction-flow represents a system’s processing. Functional testing methods are applied for testing T-F.
Transaction-flow Graph
TFG represents a behavioral (functional) model of the program (system) used for functional testing by an independent system tester.
Transaction
is a unit of work seen from system’s user point of view.
consists of a sequence of operations performed by a system, persons or external devices.
is created (birth) due to an external act & up on its completion (closure), it remains in the form of historical records.
ref boris beizer

5. U2-B A Simple Transaction
Example: the sequence of steps in a transaction in an online information retrieval system
1. accept inputs Accept Inputs
2. Validate inputs (Birth of tr.) Validate inputs
3. Transmit ack. to the user Process the request
4. Process input Update file
5. Search file Transmit output
6. Request direction from user Record transaction in log & cleanup (Closure)
Users View of a transaction : Single step
Systems view : Sequence of many operations
ref boris beizer

6. Example of a Transaction flow (diagram)U2
User (terminal) Terminal controller CPU
User
Begin
Request
order
from CPU
Type
cancel
help
Accept
Order from
CPU
Process
Form B B
Transmit
Page to
terminal C
Accept
Input
Field
More
Fields? Y
To CPU D
User wants
Review? D
CPU-
Accept
Confirm
Valid ? Y
More
Pages ? N
Done
Transmit
Diagnostic
to Terminal C
Set up
Review
ref boris beizer

7. Definitions U2
Transaction-flow Graph : a scenario between users & computer
Transaction-flow : an internal sequence of events in processing a transaction
Uses of Transaction-flow
Specifying requirements of big, online and complicated systems.
Airline reservation systems, air-traffic control systems.
Loops are less as compared to CFG. Loops are used for user input error processing
ref boris beizer

8. Implementation of Transaction-Flow (in a system)U2
Implicit in the design of system’s control structure & associated database.
No direct one-to-one correspondence between the “processes” and “decisions” of transaction-flow, and the corresponding program component.
A transaction-flow is a path taken by the transaction through a succession of processing modules.
A transaction is represented by a token.
A transaction-flow graph is a pictorial representation of what happens to the tokens.
Input S A B C D E
S : Scheduler A, B, C, D, E : Processes
Output
ref boris beizer

9. Implementation of Transaction-FlowU2
System Control Structure (architecture of the implementation) :
Front
End
Input
Queue
EXECUTIVE
SCHEDULER - AND / OR OPERATING SYSTEM
DISPATCHER
Output
Module
Process
Queues
A Processor
B Processor
C Processor
D Processor
E Processor
Application Processes
Do All B’s
Do All D’s
Disc
Reads
Do All C’s
Do All A’s
Tape
Writes
Do All E’s 2 1
Executive / Dispatcher Flowchart (a sample sequence)
ref boris beizer

10. Implementation of Transaction-FlowU2
System control structure
System is controlled by a scheduler …
A Transaction is created by filling in a Transaction Control Block (TCB) by user inputs and by placing that token on input Q of Scheduler.
Scheduler examines and places it on appropriate process Q such as A. When A finishes with the Token, it places the TCB back on the scheduler Q.
Scheduler routes it to the next process after examining the token :
It contains tables or code to route a token to the next process.
It may contain routing information only in tables.
Scheduler contains no code / data. Processing modules contain code for routing.
ref boris beizer

11. Implementation of Transaction-FlowU2
Transaction Processing System (simplified):
There are many Tr. & Tr-flows in the system.
Scheduler invokes processes A to E as well as disk & tape read & writes.
The order of execution depends on priority & other reasons.
Cyclic structure like in this example is common in process control & communication systems.
 The criteria for implementation mechanism depends on performance and resource optimization.
ref boris beizer

12. A perspective of Transaction-FlowU2
Transaction-flow testing is a block box technique. (as we assumed nothing regarding computer, communications, environment, O.S., transaction identity or structure or state.)
TFG is a kind of DFG.
TFG has tokens, & DFG has data objects with history of operations applied on them.
Many techniques of CFG apply to TFG & DFG
Decision nodes of TFG have exception exits to the central recovery process.
So, we ignore the effect of interrupts in a Transaction-flow.
ref boris beizer

13. Transaction Flows – splitting & merging decisions
U2-B
Splits of transactions (Births)
A decision point in TFG
Alternative 1
Alternative 2
Biosis
Daughter Tr.
Parent
Daughter Tr.
Parent
Mitosis
ref boris beizer

14. Transaction Flows – splitting & merging decisionsU2
Mergers of transactions
Junction
Path 2
Path 1
Continue
Daughter Tr.
Predator
Absorption
Daughter
Parent
Conjugation
ref boris beizer

15. TFG – splitting, merging TransactionsU2
NOTES:
Multiple meanings now for decision and junction symbols in a TFG.
Simple TFG model is not enough to represent multi-processor systems & associated coordination systems.
Petrinet model uses operations for all the above. But Petrinets are applied to H/W, N/W protocol testing – but not Software.
ref boris beizer

16. Simplified TFG model Simplify TFG modelU2
Simplify TFG model
Add New Tr-Flows for Biosis, Mitosis, Absorption, Conjugation
Problems for programmer, designer & test designer.
Need to design specific tests – possibility of bugs.
ref boris beizer

17. Transaction-flow Structure
U2-B
Reasons for Unstructuredness
Processes involve Human Users
2. Part of Flow from External Systems
3. Errors, Failures, Malfunctions & Recovery Actions
4. Transaction Count, Complexity. Customer & Environment
ref boris beizer

18. Transaction-flow Structure
U2-B
Reasons for Unstructuredness …
New Transactions, & Modifications
Approximation to Reality
Attempt to Structure
ref boris beizer

19. Transaction - Flow Testing - Steps
U2-B
First, Build / Obtain Transaction Flows
Represent Explicitly
Design details the Main Tr-Flows
Create From PDL
HIPO charts & Petrinet Representations
Objective – Trace the transaction
ref boris beizer

20. Transaction - Flow Testing - Steps
U2-B
Inspections, Reviews & Walkthroughs
Start From Preliminary Design
Conducting Walkthroughs
Discuss enough Transaction Types (98% Transactions)
User needs & Functional terms (Design independent)
Traceability to Requirements
ref boris beizer

21. Transaction - Flow Testing - Steps
U2-B
Inspections, Reviews & Walkthroughs …
Design Tests for C1 + C2 coverage
Additional Coverage (> C1+C2)
Paths with loops, extreme values, domain boundaries
Weird cases, long & potentially troublesome Tr.
Design Test cases for Tr. Splits & mergers
Publish Selected Test Paths early
Buyer’s Acceptance – functional & acceptance tests
ref boris beizer

22. Transaction - Flow Testing Techniques
U2-B
Path Selection
Covering Set (C1+C2) of Functionally Sensible Tr.
Add Difficult Paths
Review with designers & implementers
Exposure of interface problems & duplicated processing
Very few Implementation bugs may remain
Transaction-flow Path Covering Set belongs in
System Feature Tests
ref boris beizer

23. Transaction - Flow Testing Techniques
U2-B
Sensitization
Functionally Sensible Paths – Simple
Error, Exception, External Protocol Interface Paths - Difficult
Testing Tr.–Flows with External Interfaces
Use patches & break points, mistune, and break the rules,
ref boris beizer

24. Transaction - Flow Testing Techniques
U2-B
Instrumentation
Link Counters are not Useful.
Need
Trace
Queues on which Tokens resided
Entries to & Exits from Dispatcher
A Running Log
Make Instrumentation as part of System Design
ref boris beizer

25. Transaction - Flow Testing Techniques
U2-B
Test Data bases
Design & Maintenance of a Test Data base - Effort
Mistakes
Unawareness about design of a centrally administered test DB
Test DB design by Testers
Using one DB for all tests (need 4 to 5)
Need experienced System & Test Designers
ref boris beizer

26. Transaction - Flow Testing Techniques
U2-B
Test Execution
Use Test Execution Automation
Have to do a large # of Tests for C1+C2 coverage
ref boris beizer

27. Transaction - Flow Testing - Implementation
U2-B
Transaction based systems
TCB
Centralized, Common Processing Queues
Just O(n) Queues for Links of O(n2)
Transaction Dispatcher
Uses tables & Finite State Machines
Recovery & Other Logs
Key events in Tr – Flow
Self-Test Support
Privileged modes in Transaction control tables
ref boris beizer

28. Transaction - Flow Testing - Caution
U2-B
Transaction - Flow Testing - Caution
Hidden Languages (flow control language)
Transaction Flows based on control codes in TCB or DB
Undeclared. Syntax & Semantics are not debugged.
Possibility of bugs
ref boris beizer

29. Software Testing MethodologyU2
To Unit 3 : Data flow testing …
ref boris beizer

30. Data - Flow Testing - BasicsU2
We will see in this part of Unit 2:
Concepts of Data flows
Data-flow testing strategies
ref boris beizer

31. Data - Flow Testing - BasicsU2
Contents
Synopsis
Basics
Intro to Data flow, data flow graphs
Motivation & Assumption
Data flow model
Data Flow Testing Strategies
General strategy
Definitions
Strategies:
Slicing, Dicing, Data flow, Effectiveness
Application of DFT, Tools & Effectiveness
ref boris beizer

32. Data - Flow Testing - BasicsU2
Anomaly
Unreasonable processing on data
Use of data object before it is defined
Defined data object is not used
Data Flow Testing (DFT) uses Control Flow Graph (CFG) to explore dataflow anomalies.
DFT Leads to testing strategies between P and P1 / P2
ref boris beizer

33. Data - Flow Testing - BasicsU2
Definition:
DFT is a family of test strategies based on selecting paths through the program’s control flow in order to explore the sequence of events related to the status of data objects.
Example:
Pick enough paths to assure that every data item has been initialized prior to its use, or that all objects have been used for something.
ref boris beizer

34. Data - Flow Testing - BasicsU2
Motivation
Confidence in the program
Data dominated design Code migrates to data..
Source Code for Data Declarations
Data flow Machines vs Von Neumann’s
Abstract M I M D
Language & compiler take care of parallel computations
ref boris beizer

35. Data - Flow Testing - Basics - MotivationU2
Program Control flow with Von Neumann’s paradigm
Given m, n, p, q, find e.
e = (m+n+p+q) * (m+n-p-q)
a := m + n
b := p + q
c := a + b
d := a - b
e := c * d
a = n+m
b=p+q
c=a+b
d=a-b
e=c*d
Multiple representations of control flow graphs possible.
ref boris beizer

36. Data - Flow Testing - Basics - MotivationU2
Program Flow using Data Flow Machines paradigm
BEGIN
PAR DO
READ m, n, n, p, q
END PAR
a := m+n
b := p+q
c := a+b
d := a-b
e := c * d
END m p q n
a := m+n
b := p+q
c := a+b
d := a-b
e := c * d
The interrelations among the data items remain same.
ref boris beizer

37. Data - Flow Testing - Basics - MotivationU2
Control flow graph
Multiple representations
Data Flow Graph
A spec. for relations among the data objects.
Covering DFG => Explore all relations under some test.
ref boris beizer

38. Data - Flow Testing - BasicsU2
Assumptions
Problems in a control flow
Problems with data objects
ref boris beizer

39. Data - Flow Testing - BasicsU2
Data Flow Graphs (DFG)
It is a graph with nodes & directed links
Test the Von Neumann way -
Convert to a CFG
Annotate : program actions (weights)
ref boris beizer

40. Data - Flow Testing - BasicsU2
Data Object State & Usage
Program Actions (d, k, u):
Defined (created) - explicitly or implicitly (d)
Killed (released) - directly or indirectly (k)
Used (u)
In a calculation - (c)
In a predicate - directly or indirectly (p)
ref boris beizer

41. Data - Flow Testing - BasicsU2
Data Flow Anomalies
A Two letter sequence of Actions (d, k, u)
dd : harmless, suspicious
dk : probably a bug.
du : normal
kd : normal
kk : harmless, but probably a bug
ku : a bug
ud : normal Redefinition.
uk : normal
uu : normal A
Action
ref boris beizer

42. Data - Flow Testing - Basics - MotivationU2
Program Flow using Data Flow Machines paradigm
BEGIN
PAR DO
READ m, n, n, p, q
END PAR
a := m+n
b := p+q
c := a+b
d := a-b
e := c * d
END m p q n
a := m+n
b := p+q
c := a+b
d := a-b
e := c * d
The interrelations among the data items remain same.
ref boris beizer

43. Data - Flow Testing - Basics – Data Flow AnomaliesU2
Actions on data objects
- no action from START to this point
From this point till the EXIT
- d normal
- u anomaly
- k anomaly
k- normal
u - normal possibly an anomaly
d - possibly anomalous
ref boris beizer

44. Data - Flow Testing - BasicsU2
Data Flow Anomaly State graph
Data Object State
K, D, U, A
Processing Step
k, d, u
ref boris beizer

45. Data - Flow Testing - BasicsU2
Data Flow Anomaly State graph
Object state
Unforgiving Data flow state graph K D U A u d
k, u
d, k
d, k, u
Undefined
Anomalous
Defined
Used
ref boris beizer

46. Data - Flow Testing - BasicsU2
Data Flow Anomaly State graph
Forgiving Data flow state graph u
A  DD, DK, KU k u KU K k u k DK d k d u k U D d u d DD u d
ref boris beizer

47. Data - Flow Testing - BasicsU2
Data Flow State Graphs
Differ in processing of anomalies
Choice depends on Application, language, context
ref boris beizer

48. Data - Flow Testing - BasicsU2
Static vs Dynamic Anomaly Detection
Static analysis of data flows
Dynamic analysis
Intermediate data values
ref boris beizer

49. Data - Flow Testing - BasicsU2
Insufficiency of Static Analysis (for Data flow)
Validation of Dead Variables
Validation of pointers in Arrays
Validation of pointers for Records & pointers
Dynamic addresses for dynamic subroutine calls
Identifying False anomaly on an unachievable path
Recoverable anomalies & Alternate state graph
Concurrency, Interrupts, System Issues
ref boris beizer

50. Data - Flow Testing - BasicsU2
Data Flow Model
Based on CFG
CFG annotated with program actions
link weights : dk, dp, du etc..
Not same as DFG
For each variable and data object
ref boris beizer

51. Data - Flow Testing - Basics : Data Flow ModelU2
Procedure to Build:
Entry & Exit nodes
Unique node identification
Weights on out link
Predicated nodes
Sequence of links
Join
Concatenate weights
The converse
ref boris beizer

52. Data - Flow Testing - Basics : Data Flow ModelU2
Example: an – 1
Z = b
START a - 1
INPUT a, b, n
Z := 0
IF a = 1 THEN Z := 1
GOTO DONE1
r := 1 c := 1
POWER:
c := c * a
r := r + 1
IF r <= n THEN GO TO POWER
Z := (c – 1) / (a – 1)
DONE1:
Z := b + Z
END
ref boris beizer

53. Data - Flow Testing - Basics – Data Flow modelU2
CFG for the Example
Read a,b,n
Z := 0
Z := 1
Z := b + Z 1 2 5 6
a = 1? P1 Y
Z := (c-1)/(a-1) 3 P2 4
r < n ?
r := 1 c:=1
r := r+1, c:= c*a Y
ref boris beizer

54. Data - Flow Testing - Basics – Data Flow modelU2
CFG annotated – Data Flow Model for Z
d or kd
cd or ckd 1 d 2 5 6
a = 1? P1 Y
d or kd 3 P2 4
r < n ? Y
ref boris beizer

55. Data - Flow Testing - Basics – Data Flow modelU2
CFG annotated – Data Flow Model for c 1 2 5 6
a = 1? P1 Y c- -d 3 P2 4
ckd or kd
r < n ? Y
ref boris beizer

56. Data - Flow Testing - Basics – Data Flow modelU2
CFG annotated – Data Flow Model for r 1 2 5 6
a = 1? P1 Y p- -d 3 P2 4
ckd or kd
r < n ? Y
ref boris beizer

57. Data - Flow Testing - Basics – Data Flow modelU2
CFG annotated – Data Flow Model for b 1 d 2 5 c 6
a = 1? P1 Y 3 P2 4
r < n ? Y
ref boris beizer

58. Data - Flow Testing - Basics – Data Flow modelU2
CFG annotated – Data Flow Model for n 1 d 2 5 6
a = 1? P1 Y p- 3 P2 4
r < n ? Y
ref boris beizer

59. Data - Flow Testing - Basics – Data Flow modelU2
CFG annotated – Data Flow Model for a 1 d 2 5 6
a = 1? P1 p c- 3 P2 4 c
r < n ? Y
ref boris beizer

60. Data - Flow Testing - Basics – Data Flow modelU2
A DFM for each variable
Single DFM for multiple variables
Use weights subscripted with variables
ref boris beizer

61. Data - Flow Testing – Data Flow Testing StrategiesU2
A structural testing strategy (path testing)
Add, data flow strategies with link weights
Test path segments to have a ‘d’ (or u, k, du, dk)
ref boris beizer

62. Data - Flow Testing – Data Flow Testing StrategiesU2
DEFINITIONS
w.r.t. a variable or data object ‘v’
Assume all DF paths are achievable
Definition-clear path segment
no k, kd
Loop-free path segment
Simple path segment
du path from node i to k
definition-clear & simple c
definition-clear & loop-free p
ref boris beizer

63. Data - Flow Testing – Data Flow Testing StrategiesU2
DFT Strategies
All-du paths (ADUP)
All uses (AU) strategy
All p-uses/some c-uses and All c-uses/some p-uses
All Definitions Strategy
All p-uses, All c-uses Strategy
Purpose:
Test Design, Develop Test Cases
ref boris beizer

64. Data - Flow Testing – Data Flow Testing StrategiesU2
All-du paths (ADUP)
Strongest DFT
Every du path for every variable for every definition to every use
All uses (AU) strategy
At least one definition clear path segment from every definition of every variable to every use of that definition be exercised under some test.
At least one path segment from every definition to every use that can be reached from that definition.
ref boris beizer

65. Data - Flow Testing – Data Flow Testing StrategiesU2
All p-uses/some c-uses and All c-uses/some p-uses
APU + c
Stronger than P2
ACU + p
Weaker than P2
ref boris beizer

66. Data - Flow Testing – Data Flow Testing StrategiesU2
All Definitions Strategy (AD)
Cover every definition by at least one p or c
Weaker than ACU + p and APU + c
ref boris beizer

67. Data - Flow Testing – Data Flow Testing StrategiesU2
All-Predicate Uses, All-Computational Uses Strategy
APU :
Include definition-free path for every definition of every variable from the definition to predicate use.
ACU :
Include for every definition of every variable include at least one definition-free path from the definition to every computational use.
ref boris beizer

68. Data - Flow Testing – Data Flow Testing StrategiesU2
Ordering the strategies
All Paths
All du Paths
All-uses Paths (AU)
All-c / some-p (ACU+p)
All c uses (ACU)
All-p / some-c APU+c
All P-uses APU
All Branches P2
All Stmts P1
All Defs AD
ref boris beizer

69. Data - Flow Testing – Data Flow Testing StrategiesU2
Testing, Maintenance & Debugging in the Data Flow context
Slicing:
A static program slice is a part of a program defined wrt a variable ‘v’ and a statement ‘s’; It is the set of all statements that could affect the value of ‘v’ at stmt ‘s’.
Stmt var v
stmt2
Stmt var v
Stmt var v
Stmt s var v
ref boris beizer

70. Data - Flow Testing – Data Flow Testing StrategiesU2
Testing, Maintenance & Debugging in the Data Flow context
Dicing:
A program dice is a part of slice in which all stmts. which are known to be correct have been removed.
Obtained from ‘slice’ by incorporating correctness information from testing / debugging.
ref boris beizer

71. Data - Flow Testing – Data Flow Testing StrategiesU2
Testing, Maintenance & Debugging in the Data Flow context
Debugging:
Select a slice.
Narrow it to a dice.
Refine the dice till it’s one faulty stmt.
ref boris beizer

72. Data - Flow Testing – Data Flow Testing StrategiesU2
Testing, Maintenance & Debugging in the Data Flow context
Dynamic Slicing:
Refinement of static slicing
Only achievable paths to the stmt ‘s’ in question are included.
Slicing methods bring together testing, maintenance & debugging.
ref boris beizer

73. Data - Flow Testing - – Data Flow Testing StrategiesU2
Application of DFT
Comparison Random Testing, P2, AU by Ntafos
AU detects more bugs than
P2 with more test cases
RT with less # of test cases
Comparison of P2, AU by Sneed
AU detects more bugs with 90% Data Coverage Requirement.
ref boris beizer

74. Data - Flow Testing - – Data Flow Testing StrategiesU2
Application of DFT
Comparison of # test cases for ACU, APU, AU & ADUP
by Weyuker using ASSET testing system
Test Cases Normalized. t = a + b * d d = # binary decisions
At most d+1 Test Cases for P2 loop-free
# Test Cases / Decision
ADUP > AU > APU > ACU > revised-APU
ref boris beizer

75. Data - Flow Testing - – Data Flow Testing StrategiesU2
Application of DFT
Comparison of # test cases for ACU, APU, AU & ADUP by Shimeall & Levenson
Test Cases Normalized. t = a + b * d (d = # binary decisions)
At most d+1 Test Cases for P loop-free
# Test Cases / Decision
ADUP ~ ½ APU*
AP ~ AC
ref boris beizer

76. Data - Flow Testing - – Data Flow Testing StrategiesU2
Application of DFT
DFT vs P1, P2
DFT is Effective
Effort for Covering Path Set ~ Same
DFT Tracks the Coverage of Variables
Test Design is similar
ref boris beizer

77. Data - Flow Testing - – Data Flow Testing StrategiesU2
DFT TOOLS
Cost-effective development
Commercial tools :
Can possibly do Better than Commercial Tools
Easier Integration into a Compiler
Efficient Testing
ref boris beizer

78. Data - Flow Testing – Questions from the previous year’s exams
How is data flow testing (DFT) helpful in fulfilling gaps in path testing?
Explain the data flow Graphs (DFG).
How can anomaly be detected? Explain different types of data flow anomalies and Data flow Anomaly State Graphs.
Write applications of Data Flow Testing.
Name and explain Data flow testing strategies.
ref boris beizer

79. Data - Flow Testing – Questions from the previous year’s exams
1. Distinguish Control Flow and Transaction flow. (6 M) *
2. What is meant by transaction flow testing. Discuss its significance. (10 M)*
3. Discuss in detail data - flow testing strategies. (16 M)***
4. What are data - flow anomalies? How data flow testing can explore them? (16M)
5. What are data-flow anomalies? How data flow testing can explore them? (16M)
6. What is meant by a program slice? Discuss about static and dynamic program slicing. (8 M)
7. Explain the terms Dicing, Data-flow and Debugging. (8 M)
8. What is meant by data flow model? Discuss various components of it? (8 M)
9. Compare data flow and path flow testing strategies? (8 M)
10.Explain data-flow testing with an example. Explain its generalizations and limitations.(8 M)
ref boris beizer

80. Data - Flow Testing
U-2C
To Unit 4 … Domain Testing
ref boris beizer