1. 1
AGILE PORTUGAL 2010
AUTOMATING
INTERACTION TESTING
WITH UML SEQUENCE
DIAGRAMS: WHERE TDD
AND UML MEET
João Pascoal Faria (jpf@fe.up.pt)
25 July 2010

2. The problem
2
The development of computer-based UML (OO)
design models used as documentation only
is time consuming
the result is often wrong
the result soon becomes outdated
This is a concern both for
Educators/students: effective teaching/learning OOD
Professionals: cost-effective & agile development of
high-quality software

3. Possible solutions
3
Not using UML
Paper/hand drawings
Fast, but difficult to verify and maintain
Good for initial thinking
Reverse engineering (from code to models)
Fast, ensures consistency, difficult to abstract details away
May be good for documenting but not doing the design
Automatic code/test generation from models (MDD/MBT)
Time invested can be recovered
The quality of the models can be checked and improved
There is a good chance that they are kept up-to-date
All 3 important, can be used in combination, focus here on the last one

4. What UML diagrams? (1/2)
4
Focus here is in detailed/OOD (classes)
Not architectural design (components, etc.)
Structure/syntax: class diagrams
Generation of compile-ready class skeletons
supported by most UML tools
A limited but successful form of MDD

5. What UML diagrams? (2/2)
5
Behavior/semantics: sequence diagrams first
Captures the essence of object behavior: message
exchange among objects
Nice fit for iterative dev. of use cases/scenarios/user stories
Simple completeness/done/consistency criteria wrt class
diagrams: using all classes and public methods
Good for specifying gray-box tests (unit & interaction):
instead of full heavy-weight behavior spec,
partial light-weight behavior spec through test specs
Need tools for generating test code (e.g., xUnit) from
sequence diagrams
Check that interactions among objects occur as specified
A limited but viable form of MBT

6. The proposed solution
6
4 Complete method bodies (code)
Enterprise Architect
(EA) code generator Java Classes
UML Class Uses Java
(compile ready,
Diagrams empty methods)
Libraries
2
1
6 refactor
design Traces execution
Tests
7 iterate of methods & constructors
1 2 New
Add-in for EA
UML Test generator Trace
JUnit tests Utilities
Sequence
Diagrams New Uses (AspectJ)
3 5 Test results

7. Enterprise Architect Add-In
7
COM+ component
developed in C#
Interacts with EA through
its Object-Model (gives
access to the model
elements)
Generates JUnit source
files from sequence
diagrams (test specs)
User only has to choose
destination directory

8. Test organization
8
package spreadheettest;
import junit.framework.TestCase;
public class SpreadsheetAppTest
extends TestCase {
public void testCalculatedField() {…}
}
package spreadheettest;
import junit.framework.TestCase;
public class SpreadshhetTest
extends TestCase {
public void testCalculatedField() {…}
public void testCircularReference() {.}
}
Each sequence diagram generates one test method
Test classes & packages generated according to hierarchical model organization.

9. Simple API black-box testing
9
Constructor call
public void testCalculatedField() {
Spreadsheet s0 = new Spreadsheet("s0");
Method call and return
assertEquals("s0", s0.getName());
…
}

10. Checking internal interactions
10
…
Trace.start();
Cell x = new Cell("x", s0);
Trace.check(
new Call("Spreadsheet", s0, "addCell", new Object[] {x}, null, null));
…
expected target target method parameters return nested
internal call(s) class object value calls

11. Internal object creation & checking
11
return parameters creation

12. Internal object creation & checking
12
Stores a reference to the actual object (initially null), which is assigned on
first checking, and compared/tested on subsequent ones (by Trace.check).
…
ObjectHandler r = new ObjectHandler();
ObjectHandler c = new ObjectHandler();
ObjectHandler a = new ObjectHandler();
Trace.start();
y.setFormula("x + 1");
Trace.check(
new Call("Parser", null, "parse", new Object[] {s0, "x + 1"}, a, new Call[] {
new Call("CellReference", r, "CellReference", new Object[] {x}, null, null),
new Call("Constant", c, "Constant", new Object[] {1.0}, null, null),
new Call("Add", a, "Add", new Object[] {r, c}, null, null)}));
…
check call on check parameters check return of
internal object as internal objects internal object

13. Call tree checking
13
The actual call tree must be a super-tree of the
specified/expected call tree
Violations checked: absence of call, bad parameters,
bat target object, bad return values
Intermmediate method calls (for example auxiliary
methods) are allowed
Allows focusing the specification on the relevant
interactions (need not be a fully heavy-weight)
specification

14. Exceptions
14
try {
x.getValue();
fail(“Should have thrown CircularReferenceException");
}
catch(CircularReferenceException exception) {
}

15. User Interaction - Modeling
15
With “main”, provides a simple spreadsheetengine::SpreadsheetApp
command line interface
User
start()
Spreadsheet("s") s :Spreadsheet
start (application) and enter
(data) are keywords that enter("x = 1")
represent user actions
x :Cell
Cell("x", s)
setFormula("1")
system displays information
enter("x + 1")
to the user getValue()
1.0()
"2.0"()
Illusion of user in control: user
enter("")
action/system response
User and system run
concurrently User interaction Internal interactions

16. User Interaction – Test generation
(Internal interaction checking ommited for simplification reasons)
16
public void testCommandLineInterface {
starts console simulator Console.start();
Thread thread1 = new Thread() {
start()
public void run() {
SpreadsheetApp.main(null);
}
enter("x = 1") };
thread1.start();
enter("x = 1")
Console.enter("x = 1");
enter("x + 1")
Console.enter("x + 1");
"2.0"()
assertEquals("2.0", Console.check());
enter("")
Console.enter("");
thread1.join(1000);
wait for system termination assertFalse(thread1.isAlive());
finishes console simulator Console.stop();
}

17. User Interaction Testing – Console
17
Simulator
“around” advice redefines console I/O behavior
Currently only output via java.io.PrintStream
Currently only input via java.util.Scanner
Two Java LinkedBlockingQueue’s are used for
communication data between system and test code
“around” advice redirects input/output calls to these queues
Handles synchronization (blocking until data is available)
Handles timeouts (maximum wait time)
Application is developed normaly

18. Conclusions
18
Approach supports lightweight behavior spec
through sequence diagrams as test specs
Test code is automatically generated from
sequence diagrams
Supports effective combination of agile
modeling and TDD (test-driven development)
Quality of models is tested

19. Future Work
19
Better fault localization and messages
Multiple system behaviors allowed
Improving user interaction testing
Distributed and concurrent systems
Multiple programming languages
Circumvent some Enterprise Architect limitations

20. Thank
You