1. Software engineering for real-time systems
Section 11 Analysing and testing source code
SOFTWARE ENGINEERING for REAL-TIME SYSTEMS (© J.E.Cooling 2003)

2. Objectives Introduction To:
Explain the underlying concepts of the testing of source code.
Describe the basics of static and dynamic analysis.
Introduce code complexity metrics.
Describe coverage analysis and its use as part of the dynamic analysis process.
Illustrate test issues specifically related to object-oriented programming constructs.
SOFTWARE ENGINEERING for REAL-TIME SYSTEMS (© J.E.Cooling 2003)

3. Introduction to software testing
Part 1
Overview
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4. Why test software?
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5. Approaches to code testing
Detecting errors
Preventing errors
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6. Software code test techniques
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7. Software testing steps
Integrate sub-systems then test the complete system
Software system
Software sub-system 1
Software sub-system 2
Major
software
function 1
function 2
function 3
Code unit 1 3 2 5 4
Integration of parts
Integrate functions then test sub-systems
Integrate units then test functions
Test units
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8. Introduction to static analysis
Part 2
Static Analysis
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9. Static analysis techniques
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10. Automated static analysis tools
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11. Evaluating program structure - cyclomatic complexity measures
McCabe’s cyclomatic complexity metric: a measure of the amount of decision logic in a code unit
Control
flow
graph
Graph complexity measured using
Cyclomatic
complexity
techniques
Output from module
Source code
decision logic
Input to module
Structure described using a
Cyclomatic complexity value: the number of independent paths through a control flow graph
SOFTWARE ENGINEERING for REAL-TIME SYSTEMS (© J.E.Cooling 2003)

12. Control flow graph - simple sequence structure
Corresponding flow
Code of 'module'
graph {
Statement 1
Node 1
Accel [0] = Xnew;
Edge
(1-2)
Accel [1] = Xold;
Accel [2] = Ynew;
Statement 2
Node 2
Edge }
(2-3)
Statement 1
Statement 2
Statement 3
Flowchart
Statement 3
Node 3
Cyclomatic complexity value v(G): the number of independent paths through a control flow graph.
Here v(G) = 1
SOFTWARE ENGINEERING for REAL-TIME SYSTEMS (© J.E.Cooling 2003)

13. Control flow graph - simple selection structure
Statement
Flowchart ?
v(G) = 2
SOFTWARE ENGINEERING for REAL-TIME SYSTEMS (© J.E.Cooling 2003)

14. Control flow graph - simple iteration structure
Code of 'module'
Corresponding flow graph
Node 1 {
Edge
(1-5)
while (DataValue < 10) {
Construct 1
Edge
(1-2)
cout << "\nInput data value";
cin >> DataValue'
Construct 2
Node 2
Edge
cout << DataValue;
Edge
(4-1)
(2-3)
} /* end while */
Construct 3
Node 3
Construct 4
cout << "\nEnd of test";
Edge
(3-4)
Construct 5
Node 4 }
Statement
Flowchart ?
Node 5
v(G) = 2
SOFTWARE ENGINEERING for REAL-TIME SYSTEMS (© J.E.Cooling 2003)

15. Example control flow graphs
simplest structure
achievable
Control flow graph -
highly complex
structure
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16. Introduction to dynamic analysis
Part 3
Dynamic Analysis
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17. Black box and white box testing
Two ways of testing code
Overall function
Internal workings
‘Black box’ testing
Performed at the interfaces
‘White box’ testing
Performed on the implementation
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18. Basis of dynamic testing
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19. The test harness
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20. Features of general-purpose dynamic testing tools
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21. Coverage analysis and white box testing
‘A measure of the effectiveness and completeness of code testing.’
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22. Basis of a practical dynamic testing tool
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23. Dynamic testing and coverage analysis tool
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24. Integration and testing
Part 4
Integration
and
test strategies
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25. Combined unit and integration testing
Test code for unit A
Test 2
Integrate units A1
and A2 to form A A1
Test 1(a) A2
Test 1(b)
Phase 1: test individual units.
Phase 2: test the combined unit.
This test must exercise all features of A1 and A2.
SOFTWARE ENGINEERING for REAL-TIME SYSTEMS (© J.E.Cooling 2003)

26. Reduced integration testingv
Call node
(a) Reducedl graph - v(G) = 2 v
Reduction steps:
1. Identify ALL control structures of units A1 and A2 not concerned with external units (A).
2. Remove these from the flow graph.
Call node
(a) Original graph - v(G) = 6
Full flow graph of the integrated unit A.
Reduced flow graph of the integrated unit
SOFTWARE ENGINEERING for REAL-TIME SYSTEMS (© J.E.Cooling 2003)

27. Class and object testing
Part 5
OO systems -
Class and object testing
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28. Class and object testing
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29. OO metrics in general use
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30. Use of OO metrics Use of OO metrics (class and object) Evaluation of
Estimation of
Assessment of
Prediction of required
completeness and
coding errors
design complexity
test effort
self-containment Ÿ
LOC Ÿ
MHF Ÿ
DIT Ÿ
WMC Ÿ AD Ÿ
AHF Ÿ
NOC Ÿ
RFC Ÿ MD Ÿ
LCOM Ÿ
LCOM Ÿ
MHF Ÿ
WMC Ÿ
CBO
SOFTWARE ENGINEERING for REAL-TIME SYSTEMS (© J.E.Cooling 2003)

31. Inheritance, polymorphism and testing issues
SOFTWARE ENGINEERING for REAL-TIME SYSTEMS (© J.E.Cooling 2003)

32. Multiple clients using multiple servers having polymorphic methods
THE question: How much testing is needed?
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33. Alternative test strategies with multiple clients/servers
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34. Review of ‘Analysing and testing source code’
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