Presentation of my PhD. plan during the Doctoral Symposium track at Models'16 conference - 2nd October 2016, Saint-Malo, France.

1. A DSL FOR MODEL MUTATION
AND ITS APPLICATIONS TO
DIFFERENT DOMAINS
Pablo Gómez-Abajo
Modelling&Software Engineering Research Group
http://miso.es
Universidad Autónoma de Madrid (Spain)
Doctoral Symposium - MODELS’2016
Saint-Malo (France)

2. A model mutation is a variation of a seed model by
the application of one or more mutation operators.
Model mutation has many applications:
• Model transformation testing
• Model-based software testing
• Software product lines testing
• Automated generation of exercises
• Search-based engineering
• ...
WHAT IS A MODEL
MUTATION?
2
0
101
0
110
1
010
Seed model
Mutant models
Wodel
Seed model
...
if (a == true) then
...
...
if (a != true) then
...
Mutant model

3. PROBLEM
The existing frameworks for model mutation are:
• Specific for a language (e.g., logic formulae)
• or a domain (e.g., testing)
• Mutation operators are usually manually encoded
There is a lack of proposals facilitating:
• The definition of mutator operators
• Applicable to arbitrary languages and applications
These would facilitate the creation of domain-specific
mutation frameworks
3

4. PROPOSED SOLUTION
We propose Wodel, a DSL to facilitate the specification and
creation of model mutations in a meta-model independent way,
with:
• High-level primitives (creation, deletion, modification, etc.)
• Different selection strategies (specifically, randomly, etc.)
• Independence of target language and domain
• Compiled to Java code
• Extensible through post-processors
• Mutation registry
• Blocks of mutations
• Support for OCL constraints inside Wodel code
• Execution policies
…
4

5. TOOL ARCHITECTURE
5
seed
models
DSL
meta-
model
postProc
WODEL
engine
editor (Xtext)
code gen (Xtend)
Java code
model
mutants
code completion, validator
WODEL
program
«conforms»
check
generate, compile, execute
mutation
registry
«refers-to»«refers-to»

6. WODEL FEATURES
Support for cardinalities
• Apply mutations n times, or a number between min and max
Composite mutations
• Execute a set of mutations in one step
Correct/Incorrect mutant generation
• Mutants may satisfy seed meta-model, or not
Duplicate mutant identification
• Not only syntactically, but also semantically
Mutation primitives
• Creation, deletion, edge redirection, cloning, etc.
Model element selection strategies
• Random selection, property-based selection
Execution policies
• Parallel, sequential, distributed
Libraries of reusable mutations for particular domains
6

7. WODEL: EXAMPLE
7
Automaton
name: String
State
Transition
*
name: String
isInitial: boolean
isFinal: boolean
src
tar symbol0..1
states
* * transitions
inv1: self.states->one(s | s.isInitial)
inv2: self.states->exists(s | s.isFinal)
inv3: self.alphabet->forAll (a1, a2 |
a1.symbol = a2.symbol
implies a1 = a2)
alphabet
Symbol
symbol: String
generate 3 mutants in "out/" from "evenBinary.fa"
metamodel "http://fa.com"
with commands {
s0 = modify one State where {isFinal = true} with {reverse(isFinal)}
s1 = create State with {isFinal = true}
t0 = create Transition with {src = s0, tar = s1, symbol = one Symbol}
}

8. APPLIED MUTATIONS
REGISTRY
Optional, it is activated through the preferences page
References to seed models and mutant models
Optionally, the framework can reduce the registry (irrelevant
mutations)
Repeatability
• It will be posible to repeat the mutation process
Verbalize applied mutations forward and backward
• Text options in the automated generation of exercises
8

9. BLOCKS AND OCL
CONSTRAINTS
Wodel supports mutation blocks:
• Mutants generation by stages
• A block can take as seed models the mutants generated in previous
blocks
• Folders hierarchy for mutants identification
• Duplicated mutants control with directive repeat=no
OCL Constraints in Wodel Code:
• Applied over the generated mutants, although they
are not in the domain meta-model
9

10. EXPECTED
CONTRIBUTIONS
DSL Wodel will ease the creation of applications based on
mutations by providing support for their:
• Definition
• Execution
• Traceability
We will develop these three post-processing extensions:
• Wodel-Edu: Automated generation of exercises
• Wodel-Unit: Mutation-based software testing
• Wodel-SB: Search-and model-based software engineering
10

11. WODEL-EDU
ARCHITECTURE
Wodel-Edu is a post-processing extension to Wodel for the
automated generation of exercises
Wodel-Edu generates a web application
(http://www.wodel.eu) with three kinds of test exercises:
• Alternative response
• Multiple diagram choice
• Multiple emendation choice
11
postProc
WODEL
engine
WODEL-EDU
DSL eduTest
DSL modelDraw
mutants
model rendering
description
DSL modelText
learning
environment
exercises
description
DSL mutaText
code generator
mutation textual
description
model element
textual description

12. WODEL-EDU
EXERCISES SCHEMA
12
seed
model
WODEL
mutations
model
mutant
model
mutant
WODEL
EDU
model
mutant
seed
model
Is correct? Is correct?
exercise 1 exercise 3
seed
model
WODEL
mutations
model
mutant
model
mutant
WODEL
EDU
model
mutant
seed
model
Which one is correct?
…
model
mutant
seed
model
WODEL
mutations-1
WODEL
EDU
How to correct?
model
mutant-1
model
mutant-1
WODEL
mutations-2
model
mutant-2
mutations-1 (reversed)
mutations-2
(a) Alternative response (b) Multiple diagram choice (c) Multiple emendation choice
exercise 1 exercise 1

13. EVALUATION AND
VALIDATION
• Evaluate the expressivity of Wodel coding in it the
interesting mutations for different domains devised by us
and found in the literature
• Test the Wodel-Edu generated exercises in real university
courses (Automata Theory, Electronic Circuits, etc.)
• Use the software testing verification framework with real
software projects, with the collaboration of the industry
• Use the approach to test ATL model transformations,
complementing the previous work of our group
• Test the search-based engineering environment with the
collaboration of some experts in this area within our
department (http://aida.ii.uam.es/)
13

14. CURRENT STATUS
Wodel status
• 7 types of mutation primitives
• 4 selection strategies
• Composite mutations
• Registry extension
• Conditional expressions for specific selection
• Blocks declaration
Wodel-Edu status
• Three kinds of test exercises: alternative response, multiple
diagram choice, and multiple emendation choice
14

15. PHD. TIMELINE
15
Mar 15 Aug 15 Feb 16 Aug 16 Feb 17 Aug 17 Feb 18 Aug 18 Feb 19
Wodel DSL for Wodel-Edu
Wodel-Edu Framework
Wodel-Edu User Evaluation
Wodel DSL for Wodel-Unit
Wodel-Unit Framework
Wodel-Unit User Evaluation
Wodel DSL for Wodel-SB
Wodel-SB Framework
Wodel-SB User Evaluation
Thesis Writing

16. 16
You are invited to download the source code
of this project on GitHub:
http://gomezabajo.github.io/Wodel/
A short video demo of Wodel+Wodel-Edu:
https://youtu.be/T9n3T0jGvzg
Thank you!!
Pablo.GomezA@uam.es