Generic API Test toolBy Moshe SapirAlmog Masika

AgendaTesting practice in the industryThe Automatic API test tool conceptAttributes supplied to the developerTest coverageDesign and implementationTool demonstration

Testing practice in the industryTesting software module requires deep understanding of the modules inner logic and its interfaces semanticsCurrently, dedicated tests are written to each software componentUsually the tests do not try to retrieve functional information from the modules codeChanges in the software logic are resulted in changes in the test automation logic

Automatic API Test Tool Concept Enable the developer to add metadata to the modules codeUse .NET attributes to represent the metadata The metadata should contain information which will enable automatic testing of the moduleCreate automatic test tool that given the module and attributes can generate tests

Attributes supplied to the developer Function level attributesInput-Output Assertion:Assertion is defined by three expressions

If P is true before the function is run, then Q is true after the function is run, or one of the exceptions in L is thrown during execution For double Sqrt(double x) the developer will define:P: x > 0Q: ret ^ 2 = xL = {DivisionByZero }

Attributes supplied to the developer Function level attributes (cont)Input Parameters attributeProvide set of interesting assignments to the methods parametersFor double tan(double x) the developer will define the following assignments:X = piX = 0X = pi/2X = -1234.45*pi

Attributes supplied to the developer Class level attributesClass InstancesProvide set of interesting instances of the classFor class Int32 the developer will define the following instances:01-12^31(-2^31) + 112345-780

Attributes supplied to the developer Class level attributes (cont)Class InvariantsDefine set of Boolean expressions that should be true after and before executing any member function on an instance of the classFor Account class:class Account {string Owner;int Balance; }

The developer will define:Owner != string.EmptyBalance >= 0

Test Coverage Method level coverageGeneral testRun the method as many times as possible, using parameters supplied by the developer. If no parameters were supplied, try to generate the them

Input Output Assertion testFor each defined on the method, try to find an assignment that satisfies P, run the method and validate Q and L.

Test Coverage Assembly level coverageFunction call compositionTry to build a call graph of the functions in the assembly and generate the call paths. Validate input-output assertions and class invariants during the calls:For the classes:A, B, C, D And the functions:M1: A x B -> A M2: B x C -> D M3: A x D -> A Build the following graph:

Design and implementation Functional decompositionTest Attributes- Attributes that are available to the assembly developer.User Interface- Retrieve from the user the input required to run the test and to present him the test results. Test Engine- Responsible to run the tests and produce the test results.Results Reporting: Responsible to save the results in persistent file and redirect them to the graphic user interface.

Tester User Interface

Test Engine

Result Reporting

Test Attributes

Design and implementation Functional decompositionData flow between the different components:

User Interface

Test Parmeters

Result Reporting

Test Engine

Test Results

Processed Results

Test Engine Design: The Algorithm design pattern

+Run()

-TestedMethod

FunctionRunner

TestMatrix

+Generate() : TestMatrix

MatrixGenerator

+ExecuteTest()

-TestParameters-MatGenerator : MatrixGenerator-FuncRunner : FunctionRunner

TestExecuter

-TestedMethod

MethodTester

-TestedClass

ClassTester

-TestedAssembly

AssemblyTester

GeneralMethodTester

InputOutputAssertionsTester

ConstCorrectnessTester

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1

1

1

-Generates

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*

-Consume

1

*

ObjectBehaviorTester

FunctionCompositionTester

+Execute(in TestParameter)

-ExecutersList-TestFinishedEvent

TestEngine

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*

Test Attributes Hierarchy

System.Attribute

MethodAttribute

-InterestingInstances

Instances

ClassAttribute

-Q-P-L

InputOutputAssertion

-AssingmenstList

InputParameters

-IsConst : bool

Const

-InvariantList

Invariants

-MethodCallSequence

ObjectBehavioure

Design and implementation User Interface Structure

-TestEngine

CmdLineParser

-TestEngine-TestResultsBox-AssemblyTreeView

MainWindow

AssmeblyTreeView

TestResultBox

TestParametersDialog

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1

1

1

1

*

TestEngine

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1

1

1

User Interface Component

Test Engine Component

Test execution sequence diagram

MainWindow

InputOutputAssertionTester

Execute(TespParams)

TestEngine

ExecuteTest

ExcelReporter

UIReporter

HandleTestResults(TestResult)

HandleTestResults(TestResult)

UpdateFile

UpdateUI

MatrixGenerator

Generate

FunctionRunner

Run

SetTestParams(TesParams)

Demonstration . . .

Conclusions.NET attributes can be used to keep information that will enable automatic testing of softwareThe technique we have shown is limited to platforms that allow introduction of Meta data in the binary code (.NET, Java) The Syntax of defining expressive test attributes can be error prone (mainly due to the use of strings as function identifiers)The ability of such tools to verify large scale software is still to be investigated. Currently is seems can be used as first tire testing (BVT).