Detecting Redundant Unit Tests for AspectJ Programs

Transcription

1 Detecting Redundant Unit Tests for AspectJ Programs Tao Xie 1 Jianjun Zhao 2 Darko Marinov 3 David Notkin 4 1 North Carolina State University 2 Shanghai Jiaotong University 3 University of Illinois at Urbana-Champaign, 4 University of Washington ISSRE 2006 Nov 2006

2 Background Aspect(J): modularization of crosscutting concerns Joinpoint: location of a crosscutting concern Advice: code that should be executed when the executions reach a join point Pointcut: predicate that matches a join point

3 Example class Cell { int data; Cell next; Cell(Cell n, int i) { next = n; data = i; } } public class Stack { Cell head; } public Stack() {head = null;} public boolean push(int i) {...} public int pop() {...} Iterator iterator() {...}

4 Aspect Example I aspect NonNegative { before(stack stack):call(* Stack.*(..)) && target(stack) &&!within(nonnegative) { Iterator it = stack.iterator(); while (it.hasnext()) { int i = it.next(); if (i < 0) throw new RuntimeException("negative"); } } } Check whether stack elements are nonnegative

5 Aspect Example II aspect NonNegativeArg { before() : execution(* Stack.*(..)) {...} Object args[] = thisjoinpoint.getargs(); } for(int i=0; i<args.length; i++) { } if ((args[i] instanceof Integer) && (((Integer)args[i]).intValue() < 0)) System.err.println("Negative argument of " + thisjoinpoint.getsignature().toshortstring()); Check whether method arguments are nonnegative

6 Background (cont.) Aspect weaving (ajc, abc): used to weave aspects with base classes (affected classes) to form woven classes Aspect Class (bytecode) Advice Method (bytecode) Testing Aspect-Oriented Programs Aspectual composition behavior [WTAOP 06, Mutation 06] Aspectual behavior [AOSD 06]

7 Our Previous Aspectra Approach [AOSD 06] Aspect weaving (ajc, abc) Aspect Class (bytecode) Advice Method (bytecode) Straightforward unit testing: feed aspect classes to OO test generation tools based on bytecode Issues: arguments can be thisjoinpoint or AroundClosure objects Aspectra: generate tests for woven classes (i.e., integration testing) but focus on aspectual behavior Feed (wrapper classes) of woven classes to OO test generation tools Base classes == test drivers Leverage existing OO tools for testing AOP programs

8 From Rostra to Raspect OO redundant-test detection and reduction [ASE 04] Traditional OO test generation tools try various method sequence combinations But only distinct inputs to a method under test are needed Safer than traditional structural-coverage test reduction Experimental results showed tests generated by Parasoft Jtest 4.5 contain ~90% redundant tests New Contribution: Raspect - aspect redundant-test detection Only distinct inputs to a piece of advice are needed (for inspection)

9 Example Tests Test 1 (T1): Stack s1 = s1.push(3); s1.push(2); s1.pop(); s1.push(5); Test 2 (T2): Stack s2 = s2.push(3); s2.push(5); Test 3 (T3): Stack s3 = s3.push(3); s3.push(2); s3.pop(); s3.pop(); Each test has a method sequence on the objects of the class.

10 Defining Redundant Tests Test T is redundant w.r.t. the existing tests if T exercises no new method/advice behavior (thus, no new bug) We characterize behavior using input values Difficulties with redundant tests costly to generate, run, and inspect them may provide false confidence

11 Same inputs Same behavior Assumption: deterministic method/advice Input = object + method/advice arguments Method/Advice Execution object + method return Representing object states with rooted heaps

12 Example Tests Object states of s1 head: null Test 1 (T1): Stack s1= s1.push(3); s1.push(2); s1.pop(); s1.push(5); head 3 head 3 2 head 3 head 3 5 Each test has a method sequence on the objects of the class.

13 Example Tests Test 1 (T1): Stack s1= s1.push(3); s1.push(2); s1.pop(); s1.push(5); Object states of s1 head: null head 3 head 3 2 head 3 head 3 5 Method arguments new Stack() push(3) push(2) pop() push(5) Each test has a method sequence on the objects of the class.

14 Example Tests Test 1 (T1): Stack s1 = s1.push(3); s1.push(2); s1.pop(); s1.push(5); Test 2 (T2): Stack s2 = s2.push(3); s2.push(5); Test 3 (T3): Stack s3 = s3.push(3); s3.push(2); s3.pop(); s3.pop(); We remove T2 because T2 is redundant w.r.t. T1 in terms of method execution

15 Inputs for Advice in NonNegative aspect NonNegative { before(stack stack):call(* Stack.*(..)) && target(stack) &&!within(nonnegative) { Iterator it = stack.iterator(); while (it.hasnext()) { int i = it.next(); if (i < 0) throw new RuntimeException("negative"); } } Only Stack object state can affect the advice execution

16 Example Tests Test 1 (T1): Stack s1 = s1.push(3); s1.push(2); s1.pop(); s1.push(5); Test 2 (T2): Stack s2 = s2.push(3); s2.push(5); Test 3 (T3): Stack s3 = s3.push(3); s3.push(2); s3.pop(); s3.pop(); We remove T2 and T3 because T2 and T3 are redundant w.r.t. T1 in terms of Nonnegative advice execution

17 Inputs for Advice in NonNegativeArg aspect NonNegativeArg { before() : execution(* Stack.*(..)) {...} Object args[] = thisjoinpoint.getargs(); } for(int i=0; i<args.length; i++) { } if ((args[i] instanceof Integer) && (((Integer)args[i]).intValue() < 0)) System.err.println("Negative argument of " + thisjoinpoint.getsignature().toshortstring()); Only method argument values + method name/signature can affect the advice execution

18 Example Tests Test 1 (T1): Stack s1 = s1.push(3); s1.push(2); s1.pop(); s1.push(5); Test 2 (T2): Stack s2 = s2.push(3); s2.push(5); Test 3 (T3): Stack s3 = s3.push(3); s3.push(2); s3.pop(); s3.pop(); We remove T2 and T3 because T2 and T3 are redundant w.r.t. T1 in terms of NonNegativeArg advice execution

19 Redundant-Test Detection in AOP Testing Three kinds of units For each affected method (Rostra) woven class class under test affected method method under test For each piece of advice (Raspect) aspect class class under test advice method under test For each intertype method (Raspect) aspect class class under test intertype method method under test

20 Experimental Study Implemented Raspect by modifying Rostra Recognize aspect classes and advice/intertype methods based on naming in bytecode Applied Parasoft Jtest 4.5 on woven classes of 12 AspectJ programs to generate tests Compared three techniques: Rcov technique [Zhou et al. 04] Remove a test if it covers no aspect Rostra technique Raspect technique Hypotheses Raspect can detect a high % of redundant tests % redundant tests of Raspect > Rostra > Rcov

21 Experimental Results Rcov Rostra Raspect High % redundant tests detected by Rostra and Raspect % redundant tests detected by Raspect/Rostra > Rcov

22 Conclusion Redundant tests add cost without any benefit Defined based on method/advice input values Experimental results showed High redundancy among their generated tests Removing them does not decrease aspectual branch coverage (even fault-detection capability shown in Rostra experiments [ASE 04]) Detecting and removing redundant tests before the manual inspection of automatically generated tests

23 Questions?