Tao Xie (taoxie@cs.washington.edu) Advisor: David NotkinDepartment of Computer Science & Engineering, University of Washington, Seattle

• Syntactically identical to axioms in algebraic specifications

• Associated with counts of satisfying and violating instances

• 79 common tests and 29 special tests (8 tests are both common and special) identified out of 6777 automatically generated tests.

• 43 universal properties and 45 common properties.

SolutionSolution

Results for java.util.LinkedListResults for java.util.LinkedList

Automatic Identification of Common and Special Object-Oriented Unit TestsAutomatic Identification of Common and Special Object-Oriented Unit Tests

Related WorkRelated Work• Ernst et al., Dynamically Discovering Likely Program

Invariants to Support Program Evolution, IEEE Trans. Softw. Eng, 01.

• Henkel & Diwan, Discovering Algebraic Specifications from Java Classes, ECOOP 03.

• Xie et al., Rostra: A Framework for Detecting Redundant Object-Oriented Unit Tests, ASE 04.

Some Examples of Common/Special TestsSome Examples of Common/Special Tests

• Programmers often overlook some special or even common tests

• Automatic test generation tools produce a large number of tests

• How to automatically identify special tests and common tests from them?

ProblemProblem

• Automatically identify common and special tests without requiring specifications

• Based on dynamically inferred Statistical Algebraic Abstractions

Test generation

Common oruniversal properties

Java class bytecode Method-call

compositionStatisticalinference

Abstractiontemplates

Testidentification

Specialtests

Commontests

• Common test a satisfying instance of a universal property or common property

• Special test a violating instance of a common property

*. Common prop: remove(removeLast(S).state, m0_2).state == removeLast(remove(S, m0_2).state).stateSatisfying count: 318 (common test)

LinkedList m = new LinkedList( ); m.add (0, new Integer(-1)); m.removeLast( ); m.remove(new Integer(-1));Violating count: 42 (special test) LinkedList m = new LinkedList( ); m.add (0, new Integer(-1)); m.add (0, new Integer(0)); m.removeLast( ); m.remove(new Integer(-1));

size(clear(S).state).retval == 0

Satisfying count: 121 Violating count: 0

remove(add(S, m0_1).state, m0_2).state

== add(remove(S, m0_2).state, m0_1).state Satisfying count: 315 Violating count: 45

java.util.LinkedList as the illustrative example 25 pub methods and more than 300 LOC

class bytecode

• Generate representative method arguments

• Iteratively invoke different arguments on each non-equivalent receiver-object(e.g. five iterations)

[Xie et al. 04]

clear

S1

size

S2 == S3

S4

…

…

g(f(S, args1).state, args2).retval == constg(f(S, args1).state, args2).state == f(g(S, args1).state, args2).state

…

• Universal property: all instances are satisfying instances.

• Common property: instances are mostly (e.g. 80%) satisfying instances

• Statistical algebraic abstractions are not required to be universally true during test executions, different from properties inferred by previous approaches

[Ernst et al. 01, Henkel & Diwan 03].

ReferencesReferences

*. Common prop: remove(removeFirst(S).state, m0_2).retval == remove(S, m0_2).retval

Satisfying count: 315 (common test) LinkedList m = new LinkedList( ); m.add (0, new Integer(-1)); m.removeFirst ( ); m.remove(new Integer(1));Violating count: 45 (special test) LinkedList m = new LinkedList( ); m.add (0, new Integer(-1)); m.removeFirst ( ); m.remove(new Integer(-1));

*. Conditional universal prop: lastIndexOf(addFirst(S, m0_1).state, m0_2).retval == (lastIndexOf(S, m0_2).retval + 1) [where (m0_1==m0_2)]

Satisfying count: 120 (special test) LinkedList m = new LinkedList( );

m.addFirst(new Integer(-1)); m.lastIndexOf(new Integer(-1));

*. Common prop: removeLast(addFirst(S, m0_1).state).state

== addFirst(removeLast(S).state, m0_1).state Satisfying count: 117 (common test) LinkedList m = new LinkedList( );

m.add(0, new Integer(-1)); m.addFirst(new Integer(0)); m.removeLast ( );Violating count: 3 (special test) LinkedList m = new LinkedList( );

m.addFirst(new Integer(0)); m.removeLast ( );

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