Platzhalter für Bild, Bild auf Titelfolie hinter das Logo einsetzen Efficient Testing of Variant-Rich Software Systems Prof. Dr.-Ing. Ina Schaefer Institute of Software Engineering and Automotive Informatics Technische Universität Braunschweig ASQF Testing - Day Niedersachsen, Gifhorn, 11.11.2014
- Fields of Research Automo:ve)) So<ware)Engineering) Efficient Testing of Variant-Rich Software Variability)&)Evolu:on) Modeling) Programming) Quality)Assurance) Re?Engineering) 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 2
Testing Variant-rich Software Systems Observations: Complex systems with many interacting functions and features Many system variants and versions Consequences: Increasing testing effort Combinatorial explosion during integration and system testing Complete re-test in case of changes mostly infeasible 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 3
Agenda 1. Describing and Managing Variant-rich Systems 2. Variant Selection Techniques 3. Test effort reduction by incremental testing 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 4
Describing and Managing Variant-rich Systems 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 5
Describing and Mangaging Variant-rich Systems Variant-rich systems can be described by features which are either mandatory or optional. There can be further constraints between features Feature A excludes feature B Feature A requires feature B Feature A OR feature B has to be selected How to describe and manage these features and there connections? 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 6
Feature-Models Kang et al. [Kang90] introduced Feature-Models as possibility to represent SPLs FMs are tree-structures, which represent abstract features and their properties List Queue Stack Functions Priority Peek Priority Sync Undo size Log logger Clear require 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 7
Feature Interactions A feature is a customer-visible product characteristic. Each feature in isolation satisfies its specification. If features are combined, the single specifications are violated. There are unwanted side effects.! Feature Interaction! 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 8
Example: Combine Fire and Water Alarms If there is fire, start sprinkling system. If there is water, cut the main water line. 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 9
Reasons for Feature Interactions Intended Feature Interactions: Communication via shared variables: one feature writes, another feature reads values. Unintended Feature Interactions: Non-synchronized write access to shared resources, such as actuators, memory, shared variables, status flags In general, uncritical: Shared read access to resources, e.g., sensors 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 10
Efficient Testing of Variant-Rich Software Systems We use a combination of two approaches: Combinatorial Testing: Selection of representative subsets from a large set of possible variants Incremental Regression-based Testing: Reuse test cases and test results in order to efficiently test the selected variants 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 11
Variant Selection Techniques 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 12
Sample-based SPL Testing Problem: Number of test cases growths exponentially Solution: Combinatorial Interaction Testing (CIT) 1. Create Feature Model 2. Generate a subset of variants based on the FM, covering relevant combinations of features 3. Apply single system testing to the selected variants Efficiency of t-wise Covering Arrays (CA) " 1-wise CA: 50% of all errors " 2-wise CA: 75% of all errors Trade-Off " 3-wise CA: 95% of all errors 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 13
Set Covering Problem and Covering Arrays S = {a,b,c,d,e} SPL features M = {{a,b,c}, {b,d}, {c,d}, {d,e}} Valid product configurations Minimal Covering Array L = M 1 + M 4 Feature combinations to test Precondition: All valid product configurations already known SAT-problem, which is NP-complete Fortunately, we deal with realistic FMs 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 14
Heuristic Solution by Chvátal (1979) Idea of the algorithm: 1. = Ø 2. = Ø,, 1, 2,,., # 3. 4. 2 Worst Case: contains only subsets with different elements Best solution not guaranteed Adaptation for pairwise CA generation is easy! 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 15
ICPL by Johansen et al. (2012) Adaptation is still slow in computation! (Selected) Improvements " Finding core and dead features quickly " Early identification of invalid t-sets " Parallelization " and several more 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 16
ICPL - Evaluation ICPL can handle large-scale SPLs Compute 2-wise Covering Array with normal hardware Easily over 90% variant reduction Even with ICPL: Calculation time can be several hours 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 17
Regression-based Delta-oriented Testing 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 18
Delta-oriented Testing Approaches Goal: Reduce testing effort by only testing differences between product variants Define Deltas on test-models in model-based testing State Machines Activity Diagrams Architectures Define Deltas on requirements in natural language 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 19
Delta-oriented Test Modeling Feature- Konfiguration Kernprodukt T1: e1/e2 S1 T2: e3/ T3: e2/ S2 T4: e5/e6 S3 T5: e4/e6 Produkt T7: e1/ S4 T6: e3/ S1 + T7: e1/ Delta 1 Add + + S4 + T6: e3/ S2 + Kern + Delta 1 S1 T1: e1/e2 T2: e3/ T3: e2/ S2 Feature-Modell Application Condition S1 Delta 2 Rem - T1: e1/e2 S2 + Kern + Delta 1 + Delta 2 T4: e5/e6 S3 T5: e4/e6 T7: e1/ S4 T6: e3/ S1 S2 T2: e3/ T3: e2/ T4: e5/e6 S3 T5: e4/e6 T7: e1/ S4 T6: e3/ S3 Delta 3 Mod * S2 T5: e5/e2;e3;e4 + Kern + Delta 1 + Delta 2 + Delta 3 S1 T2: e3/ T3: e2/ S2 T4: e5/e6 S3 T5: e5/e2;e3;e4 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 20
Classification of Test Cases by Delta-Analysis Invalid V2 Variant 1 Variant 2 [ ] Variant n Test cases V1 Retest V2 Test cases V2 Test cases Vn 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 21
Delta Testing - Procedure 0. Fully test first product variant 1. Generate test cases for subsequent variants Still valid and reuseable test cases? Invalid test cases? New test cases? 2. Selection of test cases by delta analysis: Always test new test cases Select subset of reuseable test cases for re-test 3. Optionally minimize resulting test suite by redundancy elimination 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 22
Delta-Testing Strategy Variant 1 Variant 2 Core Product Variant 3 Variant 4 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 23
Case Study Body Comfort System 28 Features, 11616 Product Variants, 1 Core Product, 40 Deltas 16 Products for Pair-Wise Feature Coverage Body Comfort System Human Machine Interface Door System Security Power Window Exterior Mirror Alarm System Central Locking System require Remote Control Key Status LED Manual Power Window Automatic Power Window Finger Protection Electric Heatable Interior Monitoring Automatic Locking Control Alarm System Safety Function Control Automatic Power Window require require exclude LED Alarm System LED Finger Protection LED Central Locking System LED Power Window LED Exterior Mirror LED Heatable Legende require Mandatory Optional Alternative Or exclude require require 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 24
Case Study BCM Delta-Testing Results 80 70 60 50 40 Redundant Selektiert MoSo-PoLiTe 30 20 10 0 P0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 25
Requirements-Based Delta-oriented Testing Requirements BCS_R1 If an object is detected in the window (window pressure P > threshold), activate the finger protection to prevent the power window from moving any further. BCS_TC1 Precondition: Action: Expected Result: Test cases Window is open and an object is within the window Press move up button Window moves up, until it reaches the objects and stops BCS_R2 If the central locking system is activated and the power window is not in the top position, move the power window up, until it reaches the top position. BCS_TC2 Precondition: Action: Expected Result: CLS is activated & power window is not in top position Press move up button Power window moves to the top position and stops BCS_R3 If the move down button for the power window is pressed and there is no Central locking system, move the power Window down. Otherwise, only move down if the central locking system is deactivated BCS_R3V1 without CLS BCS_R3V2 with CLS BCS_TC3 Precondition: Action: Expected Result: BCS_TC4 Precondition: Action: Expected Result: No CLS installed Press move down button Power window moves to the bottom position and stops CLS installed and deactivated Press move down button Power window moves to the bottom position and stops BCS_R4 After the move up button has been tapped shortly (< 1 sec), the power window moves automatically up until it reaches the top position and then the movement stops. BCS_TC5 Precondition: Action: Expected Result:...... Power window is at bottom position Press move up button for less then 1 second Power window moves to the top position and stops BCS_Rn BCS_TCn 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 26
Requirements-based Delta-oriented Testing - Classification Pilot Study in Automotive Domain (Relative Figures) 70 65 60 50 50 40 30 32 20 19 18 10 - New Invalid Retest Reuse 3 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 27
Possible Strategies for Re-Test Selection Manually by test engineer (Semi-)Automatical classification of test cases into variants Formulation of requirements in delta-sets with linking of test cases to requirements Model-based impact analysis of changes by delta analysis 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 28
Conclusion Variant-rich systems lead to an exponential increasing number of products and test cases Subset selection heuristics reduce number of product variants to a representative subset which is tested. Incremental delta-testing reduces test effort between product variants by test case and test result reuse. 11 November 2014 Ina Schaefer Efficient Testing of Variant-Rich Software 29