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How Model Based Design Improves Your Testing Strategy

Steven Blyth

Steven.blyth@ansys.com 07565 654307

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Testing: What is the Point?

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VALIDATION Are we building the right thing?

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VERIFICATION

Are we building the thing right?

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VERIFICATION OF VERIFICATION

Are we testing what we are supposed to test, no more no less.

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Typical Pains in Traditional Software Development

No way to simulate and rapid proto in short loop

iteration

Non efficient design process (pseudo code)

Manual coding error prone

Time consuming activity with low added value

Late detection of functional bugs with time consuming

verification (manual process)

High level number of test on target

Development Modifications

Time consuming modification with bad impact

for Product Manufacturer Risk of exceeding the budget

Low maturity or low accuracy of requirements

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Testing Strategy with a Model Based Design Solution

System Development

High Level Requirements

Software Planning

System

Software

Overall Software Architecture

Overall Software Integration Testing

Low Level Detailed Design

SCADE Auto-Coding & Integration

Requirements Allocated to Software

SCADE Test Cases

Low Level Architecture Design

SCADE Model Simulation

SCADE Target Testing

Software Life Cycle Management

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Model Based Software Engineering

All the benefits of model based engineering – and you can TRUST the code!

Formally Defined Language + Deterministic Behaviour + Certified Code Generation

= Code you can trust

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Development Process

System Req.

Process

SW Req. Process

SW Rq Analysis

Preliminary Design Integration

Testing

Operational Testing

Unit Testing Detailed Design

Implementation

System Testing

Qualified Code Generation

HLR Based Tests

Certified

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Code Generation Qualification Impact on MB.A-5

MB.

A-5 Objective Verification method

1 Source Code complies with low-level requirements

Code generator qualification

2 Source Code complies with software architecture

Code generator qualification

3 Source Code is verifiable Code generator qualification

4 Source Code conforms to standards Code generator qualification

5 Source Code is traceable to low-level requirements

Code generator qualification

6 Source Code is accurate and consistent Code generator qualification

7 Output of software integration process is complete and correct

Analysis of the build and loading data

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Table MB.A-6 Testing of Outputs of the integration process.

1 Executable Object Code complies with high-level requirements

2 Executable Object Code is robust with high-level requirements

3 Executable Object Code complies with low-level requirements

4 Executable Object Code is robust with low-level requirements

5 Executable Object Code is compatible with target computer

Re-rerun Verification Cases

on Target

Robust Library Tests

HW/SW Integration Testing

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Table MB.A-7: Verification of Verification Summary

1 Test procedures are correct

2 Test results are correct and discrepancies explained

3 Test coverage of high-level requirements is achieved

4 Test coverage of low-level requirements is achieved

5 Test coverage of software structure (modified condition/decision) is achieved

6 Test coverage of software structure (decision coverage) is achieved

7 Test coverage of software structure (statement coverage) is achieved

8 Test coverage of software structure (data coupling and control coupling) is achieved

9 Verification of additional code, that cannot be traced to Source Code, is achieved

Review: -Test cases / procedures

-Test results -HLR-Test Cases trace

Model /Code Coverage Analysis(1)

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Summary

• Using a modelling language that is fully deterministic moves the majority of effort for both design and testing to the left side of a development cycle

• Using a certified code generator that takes as its input the formally defined model removes the need for code reviews.

• Tests are created to test the functionality of the model, which are your low level requirements

• Tests are translated for the target via a certified Test tool to verify target behaviour.

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Spend your time getting your requirements and your design right. Not on creating code and not on unit testing.

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Thank You!

Steven.blyth@ansys.com 07565 654307