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 NiCE 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 NiCE. Below is a list of the operations that throw and/or catch exceptions within NiCE'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
NiCEFormEditor	addPages()	PartInitException	Yes	No
NiCEMatrixComponentSectionPart	modify()	NumberFormatException	No	No
NiCEGeometryPage	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?
failedAuthorization()	IOException	Yes	No
BasicAuthSecuredContext	getResource()	MalformedURLException	No	Yes
BasicAuthSecuredContext	handleSecurity()	LoginException	Yes	Yes
NiCECore	start()	ServletException, NamespaceException, IOException	All yes	All no
NiCECore	setLocation()	CoreException	Yes	Yes
NiCECore	loadDefaultAreaItems()	IOException, CoreException	All yes	Yes, No
SimpleLogin	login()	IOException, UnsupportedLoginException	All yes	All yes

NiCEDataStructures

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

NiCEItem

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.

NiCEClient

Class | Method | Exception Thrown | Prints a stack trace? ------------- | ------------- | ------------- | ------------- EntryComposite | EntryComposite() | RuntimeException | No NiCEDataComponentSectionPart | NiCEDataComponentSectionPart() | RuntimeException | No NiCEFormEditor | Init() | RuntimeException | No NiCEMatrixComponentSectionPart | NiCEMatrixComponentSectionPart() | RuntimeException | No NiCESectionPage | NiCESectionPage() | RuntimeException | No NiCETableComponentSectionPart | NiCETableComponentSectionPart() | RuntimeException | No ShapeTransient | read() | IOException | No ShapeTransient | write() | IOException | No Tube | read() | IOException | No Tube | write() | IOException | No

NiCECore

Class | Method | Exception Thrown | 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 NiCECoreIApplication | start() | Exception | No

NiCEDataStructures

Class | Method | Exception Thrown | Prints a stack trace? ------------- | ------------- | ------------- | ------------- Form | addComponent() | RuntimeException | No PainfullySimpleEntry | loadFromPSFBlock() | IOException | No PainfullySimpleForm | loadComponents() | IOException | No PainfullySimpleForm | loadEntries() | IOException | No NiCEJAXBManipulator | read() | JAXBException, IOException | No NiCEJAXBManipulator | write() | JAXBException, IOException | No NiCEResource | NiCEResource() | IOException | No NiCEResource | setContents() | IOException, NullPointerException | No

NiCEItem

Class | Method | Exception Thrown | 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