From Model-Driven Testingto Test-Driven Modelling

Dr. Darius SilingasPrincipal Consultant @ No Magic

What Is this Session About?

Disclaimer: I am not and have never been a Software Tester

… but I have worked with a lot of software testers… and I know that a tester can figure out the bugs… but a developer has to fix them… and he can prevent them by using test-driven

approach

This session is about installing testing approach into software modelling activities for getting better quality models and thus better quality software based on those models

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Prerequisites

This is an advanced session, which assumes that you have:

A basic understanding of Model Driven Development

A basic understanding of Test Driven Development

A desire to build better quality software

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Towards Synergy of Trends

Improve MDA with Agile practices Raise the level of abstraction for Agile practices 4

AGILE Development

Test Driven Development

Model Driven Testing Test Driven Modelling

Eating Your Own Dog Food

Let’s practice example/test-driven approach and learn the principles of Test Driven Modelling by analyzing how to apply it to a small example system MagicTest.

MagicTest provides functionality for a teacher to create test questions, group them into a test and assign it to the class that he is teaching. The students of that classes make assessments of the test that are automatically evaluated.

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System Layers

User Interface

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Business Logic

Data Layer

Data Architecture

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MagicTest Data Structure

SelectionAsnwerClosedQuestion

OpenQuestion

AnswerOption

AssessmentInputAnswer

TestState

Question

Answer

Test

MagicTest

MagicUniversity Data Structure

UniversityMember

AcademicRoleClassStateTeacher

StudentCourse

Class

MagicUniversity

MagicUniversity Data Structures

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name : String [1]cv : String [1]title : String

Teacher

start : date [1]end : date [1]

Class

name : String [1]year : Integer [1]

Student

title : String [1]code : String [1]description : String [1]credits : Integer [1]

Course

teacher 1

0..*

subject

1 0..*

0..*

prerequisites

0..*

supervisor 1

0..*

participants 1..*

0..*

How do I know if this data structure is suitable?

Representative Data Sample

9 A sample shows inconsistency with data structure

What Can We Do When Sample Violates Data Structure

1. Fix data structure (sample is good, structure was wrong)

2. Fix data sample (sample is wrong, structure was good)

Use invalid sample in testing for ensuring that such cases are not allowed and handled appropriately in the system

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MagicUniversity Data Structures

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name : String [1]cv : String [1]title : String

Teacher

start : date [1]end : date [1]

Class

name : String [1]year : Integer [1]

Student

title : String [1]code : String [1]description : String [1]credits : Integer [1]

Course

teacher 1

0..*

subject

1 0..*

0..*

prerequisites

0..*

supervisor 1

0..*

participants 1..*

0..*

Decision: Enable multiple supervisors

1..*

Representative Data Sample

12 A sample is now in sync with data structure

Build Bigger Representative Samples

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A data designer should prepare it along with data structure Testers should take over with creating variations

System Layers

User Interface

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Business Logic

Data Layer

Modelling Business Logic in UML

Identifying business logic services as UML components

Modeling interaction scenarios as UML sequence diagrams

• The operations of business components can be created as needed• New necessary service components can be created as needed• JUnit tests or their skeletons can be generated from interaction

scenarios

15 UML tools support these scenarios quite well

Modelling Interaction Scenario at Business Logic Layer

16 Service operations are discovered based on scenarios

+startTestAssessment()+submitAnswer()+finishTestAssessment()-evaluateTestAssessment()

«component»TestAssessmentService

+getQuestion()

«component»TestManagementService

Take Test Assessment Take Test Assessmentinteraction [ ]

: TestAssessmentService : TestManagementService

getQuestion()2:

question14:

getQuestion()6:

question28:

evaluateTestAssessment()10:

evaluation11:

question13:

question27:

submitAnswer()5:

finishTestAssessment()9:

startTestAssessment()1:

...

«component»TestManagementService

...

«component»TestAssessmentService

System Layers

User Interface

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Business Logic

Data Layer

GUI Modelling in UML

GUI structure can be captured in UML class or composite structure diagrams Modern modelling tools typically provide graphical rendering to enable

better presentation for users and GUI designers/analysts

1. Identify abstract GUI screens as UML classes

2. Build abstract GUI navigation schema as UML state machine

3. Build a story board GUI sample set as UML instance specifications for validating GUI design with data samples Reuse data for GUI samples from data design (or vice versa)

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GUI Navigation Schema

19 How do I know it is suitable?

TestAssessmentWindow

StudentProfile UserDetails

TestResultsWindow

Authorized

submit login infoexit /

LoginDialog

OK

GetTestResults

EditData

OK

Finish

at (timeout)

TakeTest

all [session expired] [login incorrect] / show error msg

[password expired] / show change password fields

[password not expired]

Login

Quit

Start

[login correct]

Building GUI-Based Story Board Model (1)

20 Validates both navigation schema and screen structures

Profile

Edit Data

Get Test Results

Logout

Title:

Status:

Active:

Breaks:

Time Limit:

Instructions:

Magic Test

2009-05-25 - 2009-06-06

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60

Active

None

Java Test (Advanced)

Magic Test

UML Test (Advanced)

UML Test (Beginner)

Take Test

Building GUI-Based Story Board Model (2)

21 Validates both navigation schema and screen structures

MagicTest: UML Basics

Question 2 Question 3 ... Question 10Question 1

How many standard diagram types does UML 2 define?

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13

Pause Test < Back< Back Next > Finish Test

11Progress / 10

Building GUI-Based Story Board Model (3)

22 Validates both navigation schema and screen structures

Evaluation

Start:

End: 2009-05-29

2009-05-28 Taken Breaks:

Time elapsed (in Minutes): 17

0

Grade:

You finished the test quite well. You've made only 2 mistakes.

Keep it this way and you will finish other tests also.Maybe even better if you concentrate a little bit more andtake more time for thinking about the questions.

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Finish

Lessons Learned

1. Conceptual mistakes in design models can be found early by validating it with example/test models

2. Quality engineers need to be involved in collaborative modelling together with developers

Developers should produce essential example models Testers should take over with creating variations for a better

coverage of error-prone situations

3. Example/test-driven modelling enables achieving a better quality of model-driven software by testing design models early

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Towards Practicing Test Driven Modelling

Tool aspect: Modelling tools like MagicDraw already provide partial support for test-driven modelling – they are not a show stopper

Human aspect: Test-driven modelling requires a change in modeller’s mindset for enabling more mature modelling culture

Action point: bring these ideas back to your organisations and see if you can influence a change

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The End

Thank You for the attention!

Any Questions???Let’s Keep in Touch:

E-mail: darius.silingas@nomagic.comSkype: darius.silingasGet connected at LinkedIn social network

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