Better Exception Testing in ICE with J-Unit

Better JUNIT Testing

In many developing software applications (including ICE), unit testing has become a vital role in developing reliable, safer, and more robust products. JUNIT is one of the tools that can be used to run unit and integration tests for Java-based applications in test-driven development. Below is an example of utilizing better methods for developing unit tests for handling Exceptions on tested objects with the testing tool.

Here is a sample exception try/catch statement within a JUnit test:

//A class that tests the operation
//StringToIntegerUtility.customStrToInt(String number)
@Test
public void checkStringToInteger() {
 
    //Local declaration
 
    int number;
    String number = "Not a number";
    boolean expectedFail = false;
 
    //Setup class
    StringToIntegerUtility utility = new StringToIntegerUtility();
 
    //Call operation with try/catch statement
    try {
        number = utility.customStrToInt(number);
    } catch (NumberFormatException e) {
        //We expect this to happen
        expectedFail = true;
    }
 
    //Test is valid if it failed
    assertTrue(expectedFail);
 
}

When the utility operation is called, there has to be a try/catch statement. Try/catch statements can clutter code and confuse some forms of unit testing. What can be done is to separate these specific exception unit tests into their own methods and have JUNIT check the exceptions. Below is a better way to handle the exceptions in a JUNIT test.

//A class that tests the operation
//StringToIntegerUtility.customStrToInt(String number)
@Test(expected=java.lang.NumberFormatException.class)
public void checkStringToInteger() throws NumberFormatException {
    //Local declaration
    int number;
    String number = "Not a number";
 
    //Setup class
    StringToIntegerUtility utility = new StringToIntegerUtility();
 
    //Call operation, and this operation should
    //throw an exception.
    number = utility.customStrToInt(number);
 
}

This method cuts down on some of the more excessive try/catch statements in unit testing. It also helps to modularize the codebase in unit testing by separating out the exception cases from other tests. The expected statement catches the exception when it is thrown. Nevertheless, there are some limitations to this method. For example, when the exception is thrown, the testing ends in that method. Thus, if one were to need to write more expansive tests that utilize many exceptions, there would need to be an individual method for each exception. Secondly, this can pose a problem for identifying messages in exceptions for generic Exception handling or classes with multiple types of references. The second issue can be resolved by using the thrown.expect(class) and thrown.expectMessage(String) from the JUnit API. These types of calls are declared within the method and not annotated.

Locations of Exceptions

There are many areas in ICE where native and customized exceptions are thrown and caught within the applications. Many of them are required by overloaded applications, while others are created to catch specific errors in ICE. Below is a list of the operations that throw and/or catch exceptions within ICE's general architecture. It will also mention if the error prints out a stack trace or not. If it does, it will mention whether or not the operation is handled within the method. Note that just printing a stack trace does not constitute an operation as "being handled". Returning false on a boolean method for a failed initialization of another method because of a try/catch statement is an example of "handling" an issue.

This is a table for exceptions caught within each method.

ICEClient
Class	Method	Exception	Prints a stack trace?	Handles error?
EclipseFormWidget	display()	PartInitException	Yes	No
EclipseTestEditor	display()	PartInitException	Yes	No
ICEFormEditor	addPages()	PartInitException	Yes	No
ICEMatrixComponentSectionPart	modify()	NumberFormatException	No	No
ICEGeometryPage	createFormContent()	PartInitException	Yes	No
GeometryApplication	commit()	ClassCastException	No	No
RealSpinner	validateText()	NumberFormatException	No	Yes
ShapeMaterial	applyShape()	NumberFormatException	No	No
Itemprocessor	run()	InterruptedException	Yes	No

ICECore
Class	Method	Exception	Prints a stack trace?	Handles error?
BasicAuthSecuredContext	failedAuthorization()	IOException	Yes	No
BasicAuthSecuredContext	getResource()	MalformedURLException	No	Yes
BasicAuthSecuredContext	handleSecurity()	LoginException	Yes	Yes
ICECore	start()	ServletException, NamespaceException, IOException	All yes	All no
ICECore	setLocation()	CoreException	Yes	Yes
ICECore	loadDefaultAreaItems()	IOException, CoreException	All yes	Yes, No
SimpleLogin	login()	IOException, UnsupportedLoginException	All yes	All yes

ICEDataStructures
Class	Method	Exception	Prints a stack trace?	Handles error?
DataComponent, Entry, Form, MasterDetailsComponent	loadFromXML()	NullPointerException, JAXBException, IOException	All yes	All yes
MasterDetailsPair, MatrixComponent, TableComponent	loadFromXML()	NullPointerException, JAXBException, IOException	All yes	All yes
ComplexShape, GeometryComponent, PrimitiveShape	loadFromXML()	NullPointerException, JAXBException, IOException	All yes	All yes
Transformation, ICEObject, ICEResource	loadFromXML()	NullPointerException, JAXBException, IOException	All yes	All yes
Entry	setValue()	NumberFormatException	No	Yes
AbstractShape	getProperty()	IndexOutOfBoundsException	No	Yes
ICEObject	persistToXML()	NullPointerException, JAXBException, IOException	Yes	No
ICEResource	setContents()	NullPointerException	No	Yes

ICEItem
Class	Method	Exception	Prints a stack trace?	Handles error?
Item	process()	CoreException	Yes	No
Item	loadFromXML()	IOException, JAXBException, IOException	Yes	Yes
Item	persistToDatabase()	Exception	Yes	Yes
Item	deleteFromDatabase()	Exception	Yes	Yes
Item	updateToDatabase()	Exception	Yes	Yes
Item	loadFromDatabase()	Exception	Yes	Yes
JobLaunchAction	createSession()	JschException	Yes	No
JobLaunchAction	BufferedWriter()	IOException	Yes	No
JobLaunchAction	isLocalHost()	UknownHostException	Yes	No
JobLaunchAction	launchLocally()	IOException	Yes	Yes
JobLaunchAction	launchRemotely()	InterruptedException, JschException, FileNotFoundException, SftpException	All yes	All no
TaggedOutputWriterAction	execute()	IOException	Yes	Yes
JobLauncher	createOutputFiles()	CoreException, IOException	All yes	All no
JobLauncher	setupForm()	CoreException	Yes	No
JobLauncher	loadFromXML()	IOException, JAXBException, NullPointerException	Yes	Yes
MultiLauncher	run()	InterruptedException	Yes	No
JobProfile	process()	CoreException	Yes	No

This is a table for a list of exceptions thrown within each method of each class. Usually when an exception is thrown, an issue is handled in a higher level operation/method. Therefore "handles error" does not apply here.

ICEClient
Class	Method	Exception	Prints a stack trace?
EntryComposite	EntryComposite()	RuntimeException	No
ICEDataComponentSectionPart	ICEDataComponentSectionPart()	RuntimeException	No
ICEFormEditor	Init()	RuntimeException	No
ICEMatrixComponentSectionPart	ICEMatrixComponentSectionPart()	RuntimeException	No
ICESectionPage	ICESectionPage()	RuntimeException	No
ICETableComponentSectionPart	ICETableComponentSectionPart()	RuntimeException	No
ShapeTransient	read()	IOException	No
ShapeTransient	write()	IOException	No
Tube	read()	IOException	No
Tube	write()	IOException	No

ICECore
Class	Method	Exception	Prints a stack trace?
BasicAuthSecuredContext	handleSecurity()	IOException	No
BasicAuthSecuredContext	login()	IOException, UnsupportedCallbackException, LoginException	No
SimpleLogin	abort()	LoginException	No
SimpleLogin	commit()	LoginException	No
SimpleLogin	login()	LoginException	No
ICECoreIApplication	start()	Exception	No

ICEDataStructures
Class	Method	Exception	Prints a stack trace?
Form	addComponent()	RuntimeException	No
PainfullySimpleEntry	loadFromPSFBlock()	IOException	No
PainfullySimpleForm	loadComponents()	IOException	No
PainfullySimpleForm	loadEntries()	IOException	No
ICEJAXBManipulator	read()	JAXBException, IOException	No
ICEJAXBManipulator	write()	JAXBException, IOException	No
ICEResource	ICEResource()	IOException	No
ICEResource	setContents()	IOException, NullPointerException	No

ICEItem
Class	Method	Exception	Prints a stack trace?
Item	Item()	RuntimeException	No
Item	loadFromPSF()	IOException	No
SerializedItemBuilder	SerilaizedItemBuilder()	IOException	No

References

http://weblogs.java.net/blog/johnsmart/archive/2009/09/27/testing-exceptions-junit-47

http://kentbeck.github.com/junit/javadoc/4.10/org/junit/rules/ExpectedException.html